Processing XML with Java

Processing XML with Java

Elliotte Rusty Harold

ACM D.C.

Monday, December 4, 2000

elharo@metalab.unc.edu

http://www.ibiblio.org/xml/

Please turn off all

Where we're going

Processing XML with Java is easy

Prerequisites

Parser APIs

Part I: XML Infoset

The Infoset is the unfortunate standard to which those in retreat from the radical and most useful implications of well-formedness have rallied. At its core the Infoset insists that there is 'more' to XML than the straightforward syntax of well-formedness. By imposing its canonical semantics the Infoset obviates the infinite other semantic outcomes which might be elaborated in particular unique circumstances from an instance of well-formed XML 1.0 syntax. The question we should be asking is not whether the Infoset has chosen the correct canonical semantics, but whether the syntactic possibilities of XML 1.0 should be curtailed in this way at all.
--Walter Perry on the xml-dev mailing list

A simple example

<?xml version="1.0" encoding="UTF-8" standalone="no"?>
<?xml-stylesheet type="text/css" href="song.css"?>
<!DOCTYPE SONG SYSTEM "song.dtd">
<SONG xmlns="http://metalab.unc.edu/xml/namespace/song"
      xmlns:xlink="http://www.w3.org/1999/xlink">
  <TITLE>Hot Cop</TITLE>
  <PHOTO 
    xlink:type="simple" xlink:show="onLoad" xlink:href="hotcop.jpg"
    ALT="Victor Willis in Cop Outfit" WIDTH="100" HEIGHT="200"/>
  <COMPOSER>Jacques Morali</COMPOSER>
  <COMPOSER>Henri Belolo</COMPOSER>
  <COMPOSER>Victor Willis</COMPOSER>
  <PRODUCER>Jacques Morali</PRODUCER>
  <!-- The publisher is actually Polygram but I needed 
       an example of a general entity reference. -->
  <PUBLISHER xlink:type="simple" xlink:href="http://www.amrecords.com/">
    A &amp; M Records
  </PUBLISHER>
  <LENGTH>6:20</LENGTH>
  <YEAR>1978</YEAR>
  <ARTIST>Village People</ARTIST>
</SONG>
<!-- You can tell what album I was 
     listening to when I wrote this example -->
View in Browser

Markup and Character Data

Markup and Character Data Example

<?xml version="1.0" encoding="UTF-8" standalone="no"?>
<?xml-stylesheet type="text/css" href="song.css"?>
<!DOCTYPE SONG SYSTEM "song.dtd">
<SONG xmlns="http://www.ibiblio.org/xml/namespace/song"
      xmlns:xlink="http://www.w3.org/1999/xlink">
  <TITLE>Hot Cop</TITLE>
  <PHOTO 
    xlink:type="simple" xlink:show="onLoad" xlink:href="hotcop.jpg"
    ALT="Victor Willis in Cop Outfit" WIDTH="100" HEIGHT="200"/>
  <COMPOSER>Jacques Morali</COMPOSER>
  <COMPOSER>Henri Belolo</COMPOSER>
  <COMPOSER>Victor Willis</COMPOSER>
  <PRODUCER>Jacques Morali</PRODUCER>
  <!-- The publisher is actually Polygram but I needed 
       an example of a general entity reference. -->
  <PUBLISHER xlink:type="simple" xlink:href="http://www.amrecords.com/">
    A &amp; M Records
  </PUBLISHER>
  <LENGTH>6:20</LENGTH>
  <YEAR>1978</YEAR>
  <ARTIST>Village People</ARTIST>
</SONG>
<!-- You can tell what album I was 
     listening to when I wrote this example -->

Entities

Parsed Character Data

CDATA sections

Comments

Processing Instructions

The XML Declaration

<?xml version="1.0" encoding="UTF-8" standalone="no"?>

Document Type Declaration

<!DOCTYPE SONG SYSTEM "song.dtd">

Document Type Definition

<!ELEMENT SONG (TITLE, PHOTO?, COMPOSER+, PRODUCER*, 
 PUBLISHER*, LENGTH?, YEAR?, ARTIST+)>

<!ELEMENT TITLE (#PCDATA)>

<!ELEMENT COMPOSER (#PCDATA)>
<!ELEMENT PRODUCER (#PCDATA)>
<!ELEMENT PUBLISHER (#PCDATA)>
<!ELEMENT LENGTH (#PCDATA)>
<!-- This should be a four digit year like "1999",
     not a two-digit year like "99" -->
<!ELEMENT YEAR (#PCDATA)>

<!ELEMENT ARTIST (#PCDATA)>
<!ELEMENT PHOTO EMPTY>
<!ATTLIST PHOTO xlink:type (simple) #FIXED "simple" 
                xlink:show (onLoad) #FIXED "onLoad" 
                xlink:href CDATA #REQUIRED
                ALT CDATA #REQUIRED
                WIDTH NMTOKEN #REQUIRED
                HEIGHT NMTOKEN #REQUIRED
>
<!ATTLIST PUBLISHER xlink:type (simple) #FIXED "simple" 
                    xlink:href CDATA #REQUIRED

>
<!ATTLIST SONG xmlns CDATA       #FIXED "http://metalab.unc.edu/xml/namespace/song"
               xmlns:xlink CDATA #FIXED "http://www.w3.org/1999/xlink"
>

XML Names

Questions?

XML Namespaces

Namespace Syntax

Namespace URIs

Binding Prefixes to Namespace URIs

The Default Namespace

How Parsers Handle Namespaces

Questions?

Three Variations on a Theme

A normal XML document

<?xml version="1.0" encoding="UTF-8" standalone="no"?>
<?xml-stylesheet type="text/css" href="song.css"?>
<!DOCTYPE SONG SYSTEM "song.dtd">
<SONG xmlns="http://metalab.unc.edu/xml/namespace/song"
      xmlns:xlink="http://www.w3.org/1999/xlink">
  <TITLE>Hot Cop</TITLE>
  <PHOTO 
    xlink:type="simple" xlink:show="onLoad" xlink:href="hotcop.jpg"
    ALT="Victor Willis in Cop Outfit" WIDTH="100" HEIGHT="200"/>
  <COMPOSER>Jacques Morali</COMPOSER>
  <COMPOSER>Henri Belolo</COMPOSER>
  <COMPOSER>Victor Willis</COMPOSER>
  <PRODUCER>Jacques Morali</PRODUCER>
  <!-- The publisher is actually Polygram but I needed 
       an example of a general entity reference. -->
  <PUBLISHER xlink:type="simple" xlink:href="http://www.amrecords.com/">
    A &amp; M Records
  </PUBLISHER>
  <LENGTH>6:20</LENGTH>
  <YEAR>1978</YEAR>
  <ARTIST>Village People</ARTIST>
</SONG>
<!-- You can tell what album I was 
     listening to when I wrote this example -->

A canonical XML document

<?xml-stylesheet type="text/css" href="song.css"?><SONG xmlns="http://metalab.unc.edu/xml/namespace/song"
xmlns:xlink="http://www.w3.org/1999/xlink">&#10; <TITLE>Hot Cop</TITLE>&#10; <PHOTO ALT="Victor Willis in
Cop Outfit" HEIGHT="200" WIDTH="100" xlink:href="hotcop.jpg" xlink:show="onLoad"
xlink:type="simple"></PHOTO>&#10; <COMPOSER>Jacques Morali</COMPOSER>&#10; <COMPOSER>Henri
Belolo</COMPOSER>&#10; <COMPOSER>Victor Willis</COMPOSER>&#10; <PRODUCER>Jacques
Morali</PRODUCER>&#10; &#10; <PUBLISHER xlink:href="http://www.amrecords.com/" xlink:type="simple">&#10; A
&amp; M Records&#10; </PUBLISHER>&#10; <LENGTH>6:20</LENGTH>&#10; <YEAR>1978</YEAR>&#10;
<ARTIST>Village People</ARTIST>&#10;</SONG>

An org.w3c.dom.Document object formed by reading hotcop.xml

import org.apache.xerces.parsers.*;
import org.w3c.dom.*;
import org.xml.sax.*;
import java.io.*;

public class DOMHotCop {

  public static void main(String[] args) {
     
    DOMParser parser = new DOMParser();
    
    try {
      parser.parse("http://metalab.unc.edu/xml/examples/hot_cop.xml"); 
      Document d = parser.getDocument();
    }
    catch (SAXException e) {
      System.err.println(e); 
    }
    catch (IOException e) {
      System.err.println(e); 
    }
   
  }

}

Are these three the same thing or not?

What is the XML InfoSet?

The InfoSet defines 15 kinds of Information Items

The Document Information Item

Element Information Items

An Element Information Item Includes:

Attributes

xlink:type="simple"
xlink:href="http://www.amrecords.com/"
xlink:type =  "simple"
xlink:show = "onLoad"
xlink:href="hotcop.jpg"
ALT="Victor Willis in Cop Outfit"
WIDTH=" 100 "
HEIGHT=' 200 '

An Attribute Information Item Includes:

Comments

  <!-- The publisher is actually Polygram but I needed 
       an example of a general entity reference. -->
<!--  <PUBLISHER xlink:type="simple" xlink:href="http://www.amrecords.com/">
    A &amp; M Records
  </PUBLISHER>
  <LENGTH>6:20</LENGTH>
  <YEAR>1978</YEAR>
  <ARTIST>Village People</ARTIST>
</SONG> -->
<!-- You can tell what album I was 
     listening to when I wrote this example -->

A comment Information Item includes:

A Processing Instruction Information Item Includes:

<?robots index="yes" follow="no"?>
<?php 
  mysql_connect("database.unc.edu", "clerk", "password"); 
  $result = mysql("CYNW", "SELECT LastName, FirstName FROM Employees 
    ORDER BY LastName, FirstName"); 
  $i = 0;
  while ($i < mysql_numrows ($result)) {
     $fields = mysql_fetch_row($result);
     echo "<person>$fields[1] $fields[0] </person>\r\n";
     $i++;
  }
  mysql_close();
?>

Characters

Namespace Declarations

xmlns:rdf="http://www.w3.org/TR/REC-rdf-syntax#"
xmlns:dc="http://purl.org/dc/"
xmlns="http://www.w3.org/2000/svg"

A Namespace Declaration Information Item includes:

Document Type Declaration

<!DOCTYPE SONG SYSTEM "song.dtd">
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN"
                      "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd">

A Document Type Declaration Information Item includes:

external DTD
An entity information item for the external DTD subset.
children
Only the comment and processing instruction information items in the internal DTD subset and external DTD subsets.
parent

Entity Marker Information Items

Entity Declaration Information Items

Each entity declaration information item includes

The InfoSet Omits:

To Learn More

Questions?

Part II: Writing XML Documents with Java

Unicode

Readers and Writers

A Java program that writes Fibonacci numbers into a text file

import java.math.*;
import java.io.*;


public class FibonacciText {

  public static void main(String[] args) {

    try {
      FileOutputStream fout = new FileOutputStream("fibonacci.txt");
      OutputStreamWriter out = new OutputStreamWriter(fout, "8859_1");

      BigInteger low  = BigInteger.ZERO;
      BigInteger high = BigInteger.ONE;

      for (int i = 0; i <= 25; i++) {
        out.write(low.toString() + "\r\n");
        BigInteger temp = high;
        high = high.add(low);
        low = temp;
      }
      out.write(high.toString() + "\r\n");

      out.close();
    }
    catch (IOException e) {
      System.err.println(e);
    }

  }

}

fibonacci.txt

0
1
1
2
3
5
8
13
21
34
55
89
144
233
377
610
987
1597
2584
4181
6765
10946
17711
28657
46368
75025
196418

A Java program that writes Fibonacci numbers into an XML file

import java.math.*;
import java.io.*;


public class FibonacciXML {

  public static void main(String[] args) {
   
    try {
      FileOutputStream  fout = new FileOutputStream("fibonacci.xml");
      OutputStreamWriter out = new OutputStreamWriter(fout);      
      
      BigInteger low  = BigInteger.ZERO;
      BigInteger high = BigInteger.ONE;      
      
      out.write("<?xml version=\"1.0\"?>\r\n");  
      out.write("<Fibonacci_Numbers>\r\n");  
      for (int i = 0; i < 25; i++) {
        out.write("  <fibonacci index=\"" + i + "\">");
        out.write(low.toString());
        out.write("</fibonacci>\r\n");
        BigInteger temp = high;
        high = high.add(low);
        low = temp;
      }
      out.write("</Fibonacci_Numbers>");  
 
      out.close();
    }
    catch (IOException e) {
      System.err.println(e);
    }

  }

}

fibonacci.xml

<?xml version="1.0"?>
<Fibonacci_Numbers>
  <fibonacci index="0">0</fibonacci>
  <fibonacci index="1">1</fibonacci>
  <fibonacci index="2">1</fibonacci>
  <fibonacci index="3">2</fibonacci>
  <fibonacci index="4">3</fibonacci>
  <fibonacci index="5">5</fibonacci>
  <fibonacci index="6">8</fibonacci>
  <fibonacci index="7">13</fibonacci>
  <fibonacci index="8">21</fibonacci>
  <fibonacci index="9">34</fibonacci>
  <fibonacci index="10">55</fibonacci>
  <fibonacci index="11">89</fibonacci>
  <fibonacci index="12">144</fibonacci>
  <fibonacci index="13">233</fibonacci>
  <fibonacci index="14">377</fibonacci>
  <fibonacci index="15">610</fibonacci>
  <fibonacci index="16">987</fibonacci>
  <fibonacci index="17">1597</fibonacci>
  <fibonacci index="18">2584</fibonacci>
  <fibonacci index="19">4181</fibonacci>
  <fibonacci index="20">6765</fibonacci>
  <fibonacci index="21">10946</fibonacci>
  <fibonacci index="22">17711</fibonacci>
  <fibonacci index="23">28657</fibonacci>
  <fibonacci index="24">46368</fibonacci>
</Fibonacci_Numbers>

Suppose we want to use a different encoding than UTF-8

import java.math.*;
import java.io.*;


public class FibonacciLatin1 {

  public static void main(String[] args) {
   
    try {
      FileOutputStream fout 
       = new FileOutputStream("fibonacci_8859_1.xml");
      OutputStreamWriter out = new OutputStreamWriter(fout, "8859_1");      
      
      BigInteger low  = BigInteger.ZERO;
      BigInteger high = BigInteger.ONE;      
      
      out.write("<?xml version=\"1.0\" encoding=\"8859_1\"?>\r\n");  
      out.write("<Fibonacci_Numbers>\r\n");  
      for (int i = 0; i < 25; i++) {
        out.write("  <fibonacci index=\"" + i + "\">");
        out.write(low.toString());
        out.write("</fibonacci>\r\n");
        
        BigInteger temp = high;
        high = high.add(low);
        low = temp;
      }
      out.write("</Fibonacci_Numbers>");  
 
      out.close();
    }
    catch (IOException e) {
      System.err.println(e);
    }

  }

}

fibonacci_8859_1.xml

<?xml version="1.0" encoding="8859_1"?>
<Fibonacci_Numbers>
  <fibonacci index="0">0</fibonacci>
  <fibonacci index="1">1</fibonacci>
  <fibonacci index="2">1</fibonacci>
  <fibonacci index="3">2</fibonacci>
  <fibonacci index="4">3</fibonacci>
  <fibonacci index="5">5</fibonacci>
  <fibonacci index="6">8</fibonacci>
  <fibonacci index="7">13</fibonacci>
  <fibonacci index="8">21</fibonacci>
  <fibonacci index="9">34</fibonacci>
  <fibonacci index="10">55</fibonacci>
  <fibonacci index="11">89</fibonacci>
  <fibonacci index="12">144</fibonacci>
  <fibonacci index="13">233</fibonacci>
  <fibonacci index="14">377</fibonacci>
  <fibonacci index="15">610</fibonacci>
  <fibonacci index="16">987</fibonacci>
  <fibonacci index="17">1597</fibonacci>
  <fibonacci index="18">2584</fibonacci>
  <fibonacci index="19">4181</fibonacci>
  <fibonacci index="20">6765</fibonacci>
  <fibonacci index="21">10946</fibonacci>
  <fibonacci index="22">17711</fibonacci>
  <fibonacci index="23">28657</fibonacci>
  <fibonacci index="24">46368</fibonacci>
</Fibonacci_Numbers>

Suppose you want to include a DTD

import java.math.*;
import java.io.*;


public class FibonacciDTD {

  public static void main(String[] args) {
   
    try {
      FileOutputStream fout 
       = new FileOutputStream("valid_fibonacci.xml");
      OutputStreamWriter out = new OutputStreamWriter(fout, "UTF-8");      
      
      BigInteger low  = BigInteger.ZERO;
      BigInteger high = BigInteger.ONE;      
      
      out.write("<?xml version=\"1.0\"?>\r\n");  
      out.write("<!DOCTYPE Fibonacci_Numbers [\r\n");
      out.write("  <!ELEMENT Fibonacci_Numbers (fibonacci*)>\r\n");      
      out.write("  <!ELEMENT fibonacci (#PCDATA)>\r\n");      
      out.write("  <!ATTLIST fibonacci index CDATA #IMPLIED>\r\n");      
      out.write("]>\r\n");  
      out.write("<Fibonacci_Numbers>\r\n");  
      for (int i = 0; i < 25; i++) {
        out.write("  <fibonacci index=\"" + i + "\">");
        out.write(low.toString());
        out.write("</fibonacci>\r\n");
        
        BigInteger temp = high;
        high = high.add(low);
        low = temp;
      }
      out.write("</Fibonacci_Numbers>");  
 
      out.close();
    }
    catch (IOException e) {
      System.err.println(e);
    }

  }

}

valid_fibonacci.xml

<?xml version="1.0"?>
<!DOCTYPE Fibonacci_Numbers [
  <!ELEMENT Fibonacci_Numbers (fibonacci*)>
  <!ELEMENT fibonacci (#PCDATA)>
  <!ATTLIST fibonacci index CDATA #IMPLIED>
]>
<Fibonacci_Numbers>
  <fibonacci index="0">0</fibonacci>
  <fibonacci index="1">1</fibonacci>
  <fibonacci index="2">1</fibonacci>
  <fibonacci index="3">2</fibonacci>
  <fibonacci index="4">3</fibonacci>
  <fibonacci index="5">5</fibonacci>
  <fibonacci index="6">8</fibonacci>
  <fibonacci index="7">13</fibonacci>
  <fibonacci index="8">21</fibonacci>
  <fibonacci index="9">34</fibonacci>
  <fibonacci index="10">55</fibonacci>
  <fibonacci index="11">89</fibonacci>
  <fibonacci index="12">144</fibonacci>
  <fibonacci index="13">233</fibonacci>
  <fibonacci index="14">377</fibonacci>
  <fibonacci index="15">610</fibonacci>
  <fibonacci index="16">987</fibonacci>
  <fibonacci index="17">1597</fibonacci>
  <fibonacci index="18">2584</fibonacci>
  <fibonacci index="19">4181</fibonacci>
  <fibonacci index="20">6765</fibonacci>
  <fibonacci index="21">10946</fibonacci>
  <fibonacci index="22">17711</fibonacci>
  <fibonacci index="23">28657</fibonacci>
  <fibonacci index="24">46368</fibonacci>
</Fibonacci_Numbers>

Questions?

Converting data to XML

Sample Tab Delimited Data: Baseball Statistics

SurnameFirstNameTeamPositionGames PlayedGames StartedAtBatsRunsHitsDoublesTriplesHome runsRBIStolen BasesCaught StealingSacrifice HitsSacrifice FliesErrorsPBWalksStrike outsHit by pitch
AndersonGarret ANAOutfield15615162262183417157983336029801
BaughmanJustin ANASecond Base625419624509112010453806361
BolickFrank ANAThird Base2111453720120000001180
DisarcinaGary ANAShortstop1571555517315839335612712314021518
EdmondsJim ANAOutfield1541505991151844212591751150571141
ErstadDarin ANAOutfield133129537841593931982206133043776
GarciaCarlos ANASecond Base1910354510002010103111
GlausTroy ANAThird Base484516519369012310027015510
GreeneTodd ANAOutfield29157131840170000002200
HelfandEric ANACatcher000000000000000000
HollinsDave ANAThird Base10198363608816211391132217044697
JefferiesGregg ANAOutfield19187272560110100000050
JohnsonMark ANAFirst Base10214110000000000060
KreuterChad ANACatcher9674252276310123310519533493
MartinNorberto ANASecond Base79501952042201133132406290
MashoreDamon ANAOutfield4324981323602111010009223
MolinaBen ANACatcher201000000000000000
NevinPhil ANACatcher7565237275481827000252017675
ObrienCharlie ANACatcher625817513459041800334110332
PalmeiroOrlando ANAOutfield743416528537202154700020110
PritchettChris ANAFirst Base311980122321282000104160
SalmonTim ANADesignated Hitter1361304638413928126880101020901003
ShipleyCraig ANAThird Base77321471838712170441305225
VelardeRandy ANASecond Base5150188294913142672014034421
WalbeckMatt ANACatcher10891338418715264611557830682
WilliamsReggie ANAOutfield2973671310153310007111

A Program to convert tab delimited data to XML

import java.io.*;


public class BaseballTabToXML {

  public static void main(String[] args) {
     
    try {
      FileInputStream fin = new FileInputStream(args[0]);
      BufferedReader in 
       = new BufferedReader(new InputStreamReader(fin));
      
      FileOutputStream fout 
       = new FileOutputStream("baseballstats.xml");
      OutputStreamWriter out = new OutputStreamWriter(fout, "UTF-8");      
      out.write("<?xml version=\"1.0\"?>\r\n");  
      out.write("<players>\r\n");
      String playerStats;  
      while ((playerStats = in.readLine()) != null) {
        String[] stats = splitLine(playerStats);         
        out.write("  <player>\r\n");
          out.write("    <first_name>" + stats[1] + "</first_name>\r\n");
          out.write("    <surname>" + stats[0] + "</surname>\r\n");
          out.write("    <games_played>" + stats[4] + "</games_played>\r\n");
          out.write("    <at_bats>" + stats[6] + "</at_bats>\r\n");
          out.write("    <runs>" + stats[7] + "</runs>\r\n");
          out.write("    <hits>" + stats[8] + "</hits>\r\n");
          out.write("    <doubles>" + stats[9] + "</doubles>\r\n");
          out.write("    <triples>" + stats[10] + "</triples>\r\n");
          out.write("    <home_runs>" + stats[11] + "</home_runs>\r\n");
          out.write("    <stolen_bases>" + stats[12] + "</stolen_bases>\r\n");
          out.write("    <caught_stealing>" + stats[14] + "</caught_stealing>\r\n");
          out.write("    <sacrifice_hits>" + stats[15] + "</sacrifice_hits>\r\n");
          out.write("    <sacrifice_flies>" + stats[16] + "</sacrifice_flies>\r\n");
          out.write("    <errors>" + stats[17] + "</errors>\r\n");
          out.write("    <passed_by_ball>" + stats[18] + "</passed_by_ball>\r\n");
          out.write("    <walks>" + stats[19] + "</walks>\r\n");
          out.write("    <strike_outs>" + stats[20] + "</strike_outs>\r\n");
          out.write("    <hit_by_pitch>" + stats[21] + "</hit_by_pitch>\r\n");
        out.write("  </player>\r\n");
      }  
      out.write("</players>\r\n");  
      out.close();
      in.close();
    }
    catch (IOException e) {
      System.err.println(e);
    }
    catch (ArrayIndexOutOfBoundsException e) {
      System.out.println("Usage: java BaseballTabToXML input_file.tab");
    }

  }

  public static String[] splitLine(String playerStats) {
    
    // count the number of tabs
    int numTabs = 0;
    for (int i = 0; i < playerStats.length(); i++) {
      if (playerStats.charAt(i) == '\t') numTabs++;
    }
    int numFields = numTabs + 1;
    String[] fields = new String[numFields];
    int position = 0;
    for (int i = 0; i < numFields; i++) {
      StringBuffer field = new StringBuffer();
      while (position < playerStats.length() 
       && playerStats.charAt(position++) != '\t') {
        field.append(playerStats.charAt(position-1));
      }
      fields[i] = field.toString();
    }    
    return fields;
    
  }

}

Baseball Stats in XML

<?xml version="1.0"?>
<players>
  <player>
    <first_name>FirstName</first_name>
    <surname>Surname</surname>
    <games_played>Games Played</games_played>
    <at_bats>AtBats</at_bats>
    <runs>Runs</runs>
    <hits>Hits</hits>
    <doubles>Doubles</doubles>
    <triples>Triples</triples>
    <home_runs>Home runs</home_runs>
    <stolen_bases>RBI</stolen_bases>
    <caught_stealing>Caught Stealing</caught_stealing>
    <sacrifice_hits>Sacrifice Hits</sacrifice_hits>
    <sacrifice_flies>Sacrifice Flies</sacrifice_flies>
    <errors>Errors</errors>
    <passed_by_ball>PB</passed_by_ball>
    <walks>Walks</walks>
    <strike_outs>Strike outs</strike_outs>
    <hit_by_pitch>Hit by pitch</hit_by_pitch>
  </player>
  <player>
    <first_name>Garret </first_name>
    <surname>Anderson</surname>
    <games_played>156</games_played>
    <at_bats>622</at_bats>
    <runs>62</runs>
    <hits>183</hits>
    <doubles>41</doubles>
    <triples>7</triples>
    <home_runs>15</home_runs>
    <stolen_bases>79</stolen_bases>
    <caught_stealing>3</caught_stealing>
    <sacrifice_hits>3</sacrifice_hits>
    <sacrifice_flies>3</sacrifice_flies>
    <errors>6</errors>
    <passed_by_ball>0</passed_by_ball>
    <walks>29</walks>
    <strike_outs>80</strike_outs>
    <hit_by_pitch>1</hit_by_pitch>
  </player>
  <player>
    <first_name>Justin </first_name>
    <surname>Baughman</surname>
    <games_played>62</games_played>
    <at_bats>196</at_bats>
    <runs>24</runs>
    <hits>50</hits>
    <doubles>9</doubles>
    <triples>1</triples>
    <home_runs>1</home_runs>
    <stolen_bases>20</stolen_bases>
    <caught_stealing>4</caught_stealing>
    <sacrifice_hits>5</sacrifice_hits>
    <sacrifice_flies>3</sacrifice_flies>
    <errors>8</errors>
    <passed_by_ball>0</passed_by_ball>
    <walks>6</walks>
    <strike_outs>36</strike_outs>
    <hit_by_pitch>1</hit_by_pitch>
  </player>
  <player>
    <first_name>Frank </first_name>
    <surname>Bolick</surname>
    <games_played>21</games_played>
    <at_bats>45</at_bats>
    <runs>3</runs>
    <hits>7</hits>
    <doubles>2</doubles>
    <triples>0</triples>
    <home_runs>1</home_runs>
    <stolen_bases>2</stolen_bases>
    <caught_stealing>0</caught_stealing>
    <sacrifice_hits>0</sacrifice_hits>
    <sacrifice_flies>0</sacrifice_flies>
    <errors>0</errors>
    <passed_by_ball>0</passed_by_ball>
    <walks>11</walks>
    <strike_outs>8</strike_outs>
    <hit_by_pitch>0</hit_by_pitch>
  </player>
  <player>
    <first_name>Gary </first_name>
    <surname>Disarcina</surname>
    <games_played>157</games_played>
    <at_bats>551</at_bats>
    <runs>73</runs>
    <hits>158</hits>
    <doubles>39</doubles>
    <triples>3</triples>
    <home_runs>3</home_runs>
    <stolen_bases>56</stolen_bases>
    <caught_stealing>7</caught_stealing>
    <sacrifice_hits>12</sacrifice_hits>
    <sacrifice_flies>3</sacrifice_flies>
    <errors>14</errors>
    <passed_by_ball>0</passed_by_ball>
    <walks>21</walks>
    <strike_outs>51</strike_outs>
    <hit_by_pitch>8</hit_by_pitch>
  </player>
  <player>
    <first_name>Jim </first_name>
    <surname>Edmonds</surname>
    <games_played>154</games_played>
    <at_bats>599</at_bats>
    <runs>115</runs>
    <hits>184</hits>
    <doubles>42</doubles>
    <triples>1</triples>
    <home_runs>25</home_runs>
    <stolen_bases>91</stolen_bases>
    <caught_stealing>5</caught_stealing>
    <sacrifice_hits>1</sacrifice_hits>
    <sacrifice_flies>1</sacrifice_flies>
    <errors>5</errors>
    <passed_by_ball>0</passed_by_ball>
    <walks>57</walks>
    <strike_outs>114</strike_outs>
    <hit_by_pitch>1</hit_by_pitch>
  </player>
  <player>
    <first_name>Darin </first_name>
    <surname>Erstad</surname>
    <games_played>133</games_played>
    <at_bats>537</at_bats>
    <runs>84</runs>
    <hits>159</hits>
    <doubles>39</doubles>
    <triples>3</triples>
    <home_runs>19</home_runs>
    <stolen_bases>82</stolen_bases>
    <caught_stealing>6</caught_stealing>
    <sacrifice_hits>1</sacrifice_hits>
    <sacrifice_flies>3</sacrifice_flies>
    <errors>3</errors>
    <passed_by_ball>0</passed_by_ball>
    <walks>43</walks>
    <strike_outs>77</strike_outs>
    <hit_by_pitch>6</hit_by_pitch>
  </player>
  <player>
    <first_name>Carlos </first_name>
    <surname>Garcia</surname>
    <games_played>19</games_played>
    <at_bats>35</at_bats>
    <runs>4</runs>
    <hits>5</hits>
    <doubles>1</doubles>
    <triples>0</triples>
    <home_runs>0</home_runs>
    <stolen_bases>0</stolen_bases>
    <caught_stealing>0</caught_stealing>
    <sacrifice_hits>1</sacrifice_hits>
    <sacrifice_flies>0</sacrifice_flies>
    <errors>1</errors>
    <passed_by_ball>0</passed_by_ball>
    <walks>3</walks>
    <strike_outs>11</strike_outs>
    <hit_by_pitch>1</hit_by_pitch>
  </player>
  <player>
    <first_name>Troy </first_name>
    <surname>Glaus</surname>
    <games_played>48</games_played>
    <at_bats>165</at_bats>
    <runs>19</runs>
    <hits>36</hits>
    <doubles>9</doubles>
    <triples>0</triples>
    <home_runs>1</home_runs>
    <stolen_bases>23</stolen_bases>
    <caught_stealing>0</caught_stealing>
    <sacrifice_hits>0</sacrifice_hits>
    <sacrifice_flies>2</sacrifice_flies>
    <errors>7</errors>
    <passed_by_ball>0</passed_by_ball>
    <walks>15</walks>
    <strike_outs>51</strike_outs>
    <hit_by_pitch>0</hit_by_pitch>
  </player>
  <player>
    <first_name>Todd </first_name>
    <surname>Greene</surname>
    <games_played>29</games_played>
    <at_bats>71</at_bats>
    <runs>3</runs>
    <hits>18</hits>
    <doubles>4</doubles>
    <triples>0</triples>
    <home_runs>1</home_runs>
    <stolen_bases>7</stolen_bases>
    <caught_stealing>0</caught_stealing>
    <sacrifice_hits>0</sacrifice_hits>
    <sacrifice_flies>0</sacrifice_flies>
    <errors>0</errors>
    <passed_by_ball>0</passed_by_ball>
    <walks>2</walks>
    <strike_outs>20</strike_outs>
    <hit_by_pitch>0</hit_by_pitch>
  </player>
  <player>
    <first_name>Eric </first_name>
    <surname>Helfand</surname>
    <games_played>0</games_played>
    <at_bats>0</at_bats>
    <runs>0</runs>
    <hits>0</hits>
    <doubles>0</doubles>
    <triples>0</triples>
    <home_runs>0</home_runs>
    <stolen_bases>0</stolen_bases>
    <caught_stealing>0</caught_stealing>
    <sacrifice_hits>0</sacrifice_hits>
    <sacrifice_flies>0</sacrifice_flies>
    <errors>0</errors>
    <passed_by_ball>0</passed_by_ball>
    <walks>0</walks>
    <strike_outs>0</strike_outs>
    <hit_by_pitch>0</hit_by_pitch>
  </player>
  <player>
    <first_name>Dave </first_name>
    <surname>Hollins</surname>
    <games_played>101</games_played>
    <at_bats>363</at_bats>
    <runs>60</runs>
    <hits>88</hits>
    <doubles>16</doubles>
    <triples>2</triples>
    <home_runs>11</home_runs>
    <stolen_bases>39</stolen_bases>
    <caught_stealing>3</caught_stealing>
    <sacrifice_hits>2</sacrifice_hits>
    <sacrifice_flies>2</sacrifice_flies>
    <errors>17</errors>
    <passed_by_ball>0</passed_by_ball>
    <walks>44</walks>
    <strike_outs>69</strike_outs>
    <hit_by_pitch>7</hit_by_pitch>
  </player>
  <player>
    <first_name>Gregg </first_name>
    <surname>Jefferies</surname>
    <games_played>19</games_played>
    <at_bats>72</at_bats>
    <runs>7</runs>
    <hits>25</hits>
    <doubles>6</doubles>
    <triples>0</triples>
    <home_runs>1</home_runs>
    <stolen_bases>10</stolen_bases>
    <caught_stealing>0</caught_stealing>
    <sacrifice_hits>0</sacrifice_hits>
    <sacrifice_flies>0</sacrifice_flies>
    <errors>0</errors>
    <passed_by_ball>0</passed_by_ball>
    <walks>0</walks>
    <strike_outs>5</strike_outs>
    <hit_by_pitch>0</hit_by_pitch>
  </player>
  <player>
    <first_name>Mark </first_name>
    <surname>Johnson</surname>
    <games_played>10</games_played>
    <at_bats>14</at_bats>
    <runs>1</runs>
    <hits>1</hits>
    <doubles>0</doubles>
    <triples>0</triples>
    <home_runs>0</home_runs>
    <stolen_bases>0</stolen_bases>
    <caught_stealing>0</caught_stealing>
    <sacrifice_hits>0</sacrifice_hits>
    <sacrifice_flies>0</sacrifice_flies>
    <errors>0</errors>
    <passed_by_ball>0</passed_by_ball>
    <walks>0</walks>
    <strike_outs>6</strike_outs>
    <hit_by_pitch>0</hit_by_pitch>
  </player>
  <player>
    <first_name>Chad </first_name>
    <surname>Kreuter</surname>
    <games_played>96</games_played>
    <at_bats>252</at_bats>
    <runs>27</runs>
    <hits>63</hits>
    <doubles>10</doubles>
    <triples>1</triples>
    <home_runs>2</home_runs>
    <stolen_bases>33</stolen_bases>
    <caught_stealing>0</caught_stealing>
    <sacrifice_hits>5</sacrifice_hits>
    <sacrifice_flies>1</sacrifice_flies>
    <errors>9</errors>
    <passed_by_ball>5</passed_by_ball>
    <walks>33</walks>
    <strike_outs>49</strike_outs>
    <hit_by_pitch>3</hit_by_pitch>
  </player>
  <player>
    <first_name>Norberto </first_name>
    <surname>Martin</surname>
    <games_played>79</games_played>
    <at_bats>195</at_bats>
    <runs>20</runs>
    <hits>42</hits>
    <doubles>2</doubles>
    <triples>0</triples>
    <home_runs>1</home_runs>
    <stolen_bases>13</stolen_bases>
    <caught_stealing>1</caught_stealing>
    <sacrifice_hits>3</sacrifice_hits>
    <sacrifice_flies>2</sacrifice_flies>
    <errors>4</errors>
    <passed_by_ball>0</passed_by_ball>
    <walks>6</walks>
    <strike_outs>29</strike_outs>
    <hit_by_pitch>0</hit_by_pitch>
  </player>
  <player>
    <first_name>Damon </first_name>
    <surname>Mashore</surname>
    <games_played>43</games_played>
    <at_bats>98</at_bats>
    <runs>13</runs>
    <hits>23</hits>
    <doubles>6</doubles>
    <triples>0</triples>
    <home_runs>2</home_runs>
    <stolen_bases>11</stolen_bases>
    <caught_stealing>0</caught_stealing>
    <sacrifice_hits>1</sacrifice_hits>
    <sacrifice_flies>0</sacrifice_flies>
    <errors>0</errors>
    <passed_by_ball>0</passed_by_ball>
    <walks>9</walks>
    <strike_outs>22</strike_outs>
    <hit_by_pitch>3</hit_by_pitch>
  </player>
  <player>
    <first_name>Ben </first_name>
    <surname>Molina</surname>
    <games_played>2</games_played>
    <at_bats>1</at_bats>
    <runs>0</runs>
    <hits>0</hits>
    <doubles>0</doubles>
    <triples>0</triples>
    <home_runs>0</home_runs>
    <stolen_bases>0</stolen_bases>
    <caught_stealing>0</caught_stealing>
    <sacrifice_hits>0</sacrifice_hits>
    <sacrifice_flies>0</sacrifice_flies>
    <errors>0</errors>
    <passed_by_ball>0</passed_by_ball>
    <walks>0</walks>
    <strike_outs>0</strike_outs>
    <hit_by_pitch>0</hit_by_pitch>
  </player>
  <player>
    <first_name>Phil </first_name>
    <surname>Nevin</surname>
    <games_played>75</games_played>
    <at_bats>237</at_bats>
    <runs>27</runs>
    <hits>54</hits>
    <doubles>8</doubles>
    <triples>1</triples>
    <home_runs>8</home_runs>
    <stolen_bases>27</stolen_bases>
    <caught_stealing>0</caught_stealing>
    <sacrifice_hits>0</sacrifice_hits>
    <sacrifice_flies>2</sacrifice_flies>
    <errors>5</errors>
    <passed_by_ball>20</passed_by_ball>
    <walks>17</walks>
    <strike_outs>67</strike_outs>
    <hit_by_pitch>5</hit_by_pitch>
  </player>
  <player>
    <first_name>Charlie </first_name>
    <surname>Obrien</surname>
    <games_played>62</games_played>
    <at_bats>175</at_bats>
    <runs>13</runs>
    <hits>45</hits>
    <doubles>9</doubles>
    <triples>0</triples>
    <home_runs>4</home_runs>
    <stolen_bases>18</stolen_bases>
    <caught_stealing>0</caught_stealing>
    <sacrifice_hits>3</sacrifice_hits>
    <sacrifice_flies>3</sacrifice_flies>
    <errors>4</errors>
    <passed_by_ball>1</passed_by_ball>
    <walks>10</walks>
    <strike_outs>33</strike_outs>
    <hit_by_pitch>2</hit_by_pitch>
  </player>
  <player>
    <first_name>Orlando </first_name>
    <surname>Palmeiro</surname>
    <games_played>74</games_played>
    <at_bats>165</at_bats>
    <runs>28</runs>
    <hits>53</hits>
    <doubles>7</doubles>
    <triples>2</triples>
    <home_runs>0</home_runs>
    <stolen_bases>21</stolen_bases>
    <caught_stealing>4</caught_stealing>
    <sacrifice_hits>7</sacrifice_hits>
    <sacrifice_flies>0</sacrifice_flies>
    <errors>0</errors>
    <passed_by_ball>0</passed_by_ball>
    <walks>20</walks>
    <strike_outs>11</strike_outs>
    <hit_by_pitch>0</hit_by_pitch>
  </player>
  <player>
    <first_name>Chris </first_name>
    <surname>Pritchett</surname>
    <games_played>31</games_played>
    <at_bats>80</at_bats>
    <runs>12</runs>
    <hits>23</hits>
    <doubles>2</doubles>
    <triples>1</triples>
    <home_runs>2</home_runs>
    <stolen_bases>8</stolen_bases>
    <caught_stealing>0</caught_stealing>
    <sacrifice_hits>0</sacrifice_hits>
    <sacrifice_flies>0</sacrifice_flies>
    <errors>1</errors>
    <passed_by_ball>0</passed_by_ball>
    <walks>4</walks>
    <strike_outs>16</strike_outs>
    <hit_by_pitch>0</hit_by_pitch>
  </player>
  <player>
    <first_name>Tim </first_name>
    <surname>Salmon</surname>
    <games_played>136</games_played>
    <at_bats>463</at_bats>
    <runs>84</runs>
    <hits>139</hits>
    <doubles>28</doubles>
    <triples>1</triples>
    <home_runs>26</home_runs>
    <stolen_bases>88</stolen_bases>
    <caught_stealing>1</caught_stealing>
    <sacrifice_hits>0</sacrifice_hits>
    <sacrifice_flies>10</sacrifice_flies>
    <errors>2</errors>
    <passed_by_ball>0</passed_by_ball>
    <walks>90</walks>
    <strike_outs>100</strike_outs>
    <hit_by_pitch>3</hit_by_pitch>
  </player>
  <player>
    <first_name>Craig </first_name>
    <surname>Shipley</surname>
    <games_played>77</games_played>
    <at_bats>147</at_bats>
    <runs>18</runs>
    <hits>38</hits>
    <doubles>7</doubles>
    <triples>1</triples>
    <home_runs>2</home_runs>
    <stolen_bases>17</stolen_bases>
    <caught_stealing>4</caught_stealing>
    <sacrifice_hits>4</sacrifice_hits>
    <sacrifice_flies>1</sacrifice_flies>
    <errors>3</errors>
    <passed_by_ball>0</passed_by_ball>
    <walks>5</walks>
    <strike_outs>22</strike_outs>
    <hit_by_pitch>5</hit_by_pitch>
  </player>
  <player>
    <first_name>Randy </first_name>
    <surname>Velarde</surname>
    <games_played>51</games_played>
    <at_bats>188</at_bats>
    <runs>29</runs>
    <hits>49</hits>
    <doubles>13</doubles>
    <triples>1</triples>
    <home_runs>4</home_runs>
    <stolen_bases>26</stolen_bases>
    <caught_stealing>2</caught_stealing>
    <sacrifice_hits>0</sacrifice_hits>
    <sacrifice_flies>1</sacrifice_flies>
    <errors>4</errors>
    <passed_by_ball>0</passed_by_ball>
    <walks>34</walks>
    <strike_outs>42</strike_outs>
    <hit_by_pitch>1</hit_by_pitch>
  </player>
  <player>
    <first_name>Matt </first_name>
    <surname>Walbeck</surname>
    <games_played>108</games_played>
    <at_bats>338</at_bats>
    <runs>41</runs>
    <hits>87</hits>
    <doubles>15</doubles>
    <triples>2</triples>
    <home_runs>6</home_runs>
    <stolen_bases>46</stolen_bases>
    <caught_stealing>1</caught_stealing>
    <sacrifice_hits>5</sacrifice_hits>
    <sacrifice_flies>5</sacrifice_flies>
    <errors>7</errors>
    <passed_by_ball>8</passed_by_ball>
    <walks>30</walks>
    <strike_outs>68</strike_outs>
    <hit_by_pitch>2</hit_by_pitch>
  </player>
  <player>
    <first_name>Reggie </first_name>
    <surname>Williams</surname>
    <games_played>29</games_played>
    <at_bats>36</at_bats>
    <runs>7</runs>
    <hits>13</hits>
    <doubles>1</doubles>
    <triples>0</triples>
    <home_runs>1</home_runs>
    <stolen_bases>5</stolen_bases>
    <caught_stealing>3</caught_stealing>
    <sacrifice_hits>1</sacrifice_hits>
    <sacrifice_flies>0</sacrifice_flies>
    <errors>0</errors>
    <passed_by_ball>0</passed_by_ball>
    <walks>7</walks>
    <strike_outs>11</strike_outs>
    <hit_by_pitch>1</hit_by_pitch>
  </player>
</players>

Converting data to XML while Processing it

import java.io.*;
import java.text.*;
import java.util.*;

public class BattingAverage {

  public static void main(String[] args) {

    try {
      FileInputStream fin = new FileInputStream(args[0]);
      BufferedReader in
       = new BufferedReader(new InputStreamReader(fin));

      FileOutputStream fout
       = new FileOutputStream("battingaverages.xml");
      OutputStreamWriter out
       = new OutputStreamWriter(fout, "UTF-8");
      out.write("<?xml version=\"1.0\"?>\r\n");
      out.write("<players>\r\n");
      String playerStats;

      // for formatting batting averages
      DecimalFormat averages = (DecimalFormat)
        NumberFormat.getNumberInstance(Locale.US);
      averages.setMaximumFractionDigits(3);
      averages.setMinimumFractionDigits(3);
      averages.setMinimumIntegerDigits(0);

      while ((playerStats = in.readLine()) != null) {
        String[] stats = splitLine(playerStats);

        String formattedAverage;
        try {
          int atBats         = Integer.parseInt(stats[6]);
          int hits           = Integer.parseInt(stats[8]);
          int walks          = Integer.parseInt(stats[19]);
          int hitByPitch     = Integer.parseInt(stats[21]);
          int sacrificeFlies = Integer.parseInt(stats[16]);
          int sacrificeHits  = Integer.parseInt(stats[15]);

          int officialAtBats
           = atBats - walks - hitByPitch - sacrificeHits;
          if (officialAtBats <= 0) formattedAverage = "N/A";
          else {
            double average = hits / (double) officialAtBats;
            formattedAverage = averages.format(average);
          }
        }
        catch (Exception e) {
          // skip this player
          continue;
        }

        out.write("  <player>\r\n");
        out.write("    <first_name>" + stats[1] + "</first_name>\r\n");
        out.write("    <surname>" + stats[0] + "</surname>\r\n");
        out.write("    <batting_average>" + formattedAverage
         + "</batting_average>\r\n");
        out.write("  </player>\r\n");
      }
      out.write("</players>\r\n");
      out.close();
      in.close();
    }
    catch (IOException e) {
      System.err.println(e);
    }
    catch (ArrayIndexOutOfBoundsException e) {
      System.out.println("Usage: java BattingAverage input_file.tab");
    }

  }

  public static String[] splitLine(String playerStats) {

    // count the number of tabs
    int numTabs = 0;
    for (int i = 0; i < playerStats.length(); i++) {
      if (playerStats.charAt(i) == '\t') numTabs++;
    }
    int numFields = numTabs + 1;
    String[] fields = new String[numFields];
    int position = 0;
    for (int i = 0; i < numFields; i++) {
      StringBuffer field = new StringBuffer();
      while (position < playerStats.length()
       && playerStats.charAt(position++) != '\t') {
        field.append(playerStats.charAt(position-1));
      }
      fields[i] = field.toString();
    }
    return fields;

  }

}

Batting Averages in XML

<?xml version="1.0"?>
<players>
  <player>
    <first_name>Garret </first_name>
    <surname>Anderson</surname>
    <batting_average>.311</batting_average>
  </player>
  <player>
    <first_name>Justin </first_name>
    <surname>Baughman</surname>
    <batting_average>.272</batting_average>
  </player>
  <player>
    <first_name>Frank </first_name>
    <surname>Bolick</surname>
    <batting_average>.206</batting_average>
  </player>
  <player>
    <first_name>Gary </first_name>
    <surname>Disarcina</surname>
    <batting_average>.310</batting_average>
  </player>
  <player>
    <first_name>Jim </first_name>
    <surname>Edmonds</surname>
    <batting_average>.341</batting_average>
  </player>
  <player>
    <first_name>Darin </first_name>
    <surname>Erstad</surname>
    <batting_average>.326</batting_average>
  </player>
  <player>
    <first_name>Carlos </first_name>
    <surname>Garcia</surname>
    <batting_average>.167</batting_average>
  </player>
  <player>
    <first_name>Troy </first_name>
    <surname>Glaus</surname>
    <batting_average>.240</batting_average>
  </player>
  <player>
    <first_name>Todd </first_name>
    <surname>Greene</surname>
    <batting_average>.261</batting_average>
  </player>
  <player>
    <first_name>Eric </first_name>
    <surname>Helfand</surname>
    <batting_average>N/A</batting_average>
  </player>
  <player>
    <first_name>Dave </first_name>
    <surname>Hollins</surname>
    <batting_average>.284</batting_average>
  </player>
  <player>
    <first_name>Gregg </first_name>
    <surname>Jefferies</surname>
    <batting_average>.347</batting_average>
  </player>
  <player>
    <first_name>Mark </first_name>
    <surname>Johnson</surname>
    <batting_average>.071</batting_average>
  </player>
  <player>
    <first_name>Chad </first_name>
    <surname>Kreuter</surname>
    <batting_average>.299</batting_average>
  </player>
  <player>
    <first_name>Norberto </first_name>
    <surname>Martin</surname>
    <batting_average>.226</batting_average>
  </player>
  <player>
    <first_name>Damon </first_name>
    <surname>Mashore</surname>
    <batting_average>.271</batting_average>
  </player>
  <player>
    <first_name>Ben </first_name>
    <surname>Molina</surname>
    <batting_average>.000</batting_average>
  </player>
  <player>
    <first_name>Phil </first_name>
    <surname>Nevin</surname>
    <batting_average>.251</batting_average>
  </player>
  <player>
    <first_name>Charlie </first_name>
    <surname>Obrien</surname>
    <batting_average>.281</batting_average>
  </player>
  <player>
    <first_name>Orlando </first_name>
    <surname>Palmeiro</surname>
    <batting_average>.384</batting_average>
  </player>
  <player>
    <first_name>Chris </first_name>
    <surname>Pritchett</surname>
    <batting_average>.303</batting_average>
  </player>
  <player>
    <first_name>Tim </first_name>
    <surname>Salmon</surname>
    <batting_average>.376</batting_average>
  </player>
  <player>
    <first_name>Craig </first_name>
    <surname>Shipley</surname>
    <batting_average>.286</batting_average>
  </player>
  <player>
    <first_name>Randy </first_name>
    <surname>Velarde</surname>
    <batting_average>.320</batting_average>
  </player>
  <player>
    <first_name>Matt </first_name>
    <surname>Walbeck</surname>
    <batting_average>.289</batting_average>
  </player>
  <player>
    <first_name>Reggie </first_name>
    <surname>Williams</surname>
    <batting_average>.481</batting_average>
  </player>
</players>

The point is this:

Questions?

To Learn More

Part III: Reading XML Documents with SAX

SAX

SAX Parsers for Java

Parser URL Validating Namespaces DOM1 DOM2 SAX1 SAX2 License
Apache XML Project's Xerces Java http://xml.apache.org/xerces-j/index.html X X X X X X Apache Software License, Version 1.1
IBM's XML for Java http://www.alphaworks.ibm.com/formula/xml X X X X X X License
James Clark's XP http://www.jclark.com/xml/xp/index.html      X  Modified BSD
Microstar's Ælfred http://home.pacbell.net/david-b/xml/ Namespaces DOM1DOM2SAX1SAX2open source
Silfide's SXP http://www.loria.fr/projets/XSilfide/EN/sxp/    X   X  Non-GPL viral open source license
Sun's Java API for XML http://java.sun.com/products/xml X X X   X   free beer
Oracle's XML Parser for Java http://technet.oracle.com/ X X X   X  free beer

SAX1

SAX2

The SAX2 Process

  1. Use the factory method XMLReaderFactory.createXMLReader() to retrieve a parser-specific implementation of the XMLReader interface

  2. Your code registers a ContentHandler with the parser

  3. An InputSource feeds the document into the parser

  4. As the document is read, the parser calls back to the methods of the ContentHandler to tell it what it's seeing in the document.

Making an XMLReader

Parsing a Document with XMLReader

import org.xml.sax.*;
import org.xml.sax.helpers.*;
import java.io.*;


public class SAX2Checker {

  public static void main(String[] args) {

    XMLReader parser;
    try {
      parser = XMLReaderFactory.createXMLReader();
    }
    catch (SAXException ex) {
      try {
        parser = XMLReaderFactory.createXMLReader(
         "org.apache.xerces.parsers.SAXParser");
      }
      catch (SAXException ex2) {
        System.out.println("Could not locate a parser."
         + "Please set the the org.xml.sax.driver property.");
        return;
      }
    }

    if (args.length == 0) {
      System.out.println("Usage: java SAX2Checker URL1 URL2...");
    }

    // start parsing...
    for (int i = 0; i < args.length; i++) {

      // command line should offer URIs or file names
      try {
        parser.parse(args[i]);
        // If there are no well-formedness errors
        // then no exception is thrown
        System.out.println(args[i] + " is well formed.");
      }
      catch (SAXParseException e) { // well-formedness error
        System.out.println(args[i] + " is not well formed.");
        System.out.println(e.getMessage()
         + " at line " + e.getLineNumber()
         + ", column " + e.getColumnNumber());
      }
      catch (SAXException e) { // some other kind of error
        System.out.println(e.getMessage());
      }
      catch (IOException e) {
        System.out.println("Could not check " + args[i]
         + " because of the IOException " + e);
      }

    }

  }

}

Sample Output from SAX2Checker

C:\>java SAX2Checker http://metalab.unc.edu/xml/
http://metalab.unc.edu/xml/ is not well formed.
The element type "dt" must be terminated by the 
matching end-tag "</dt>". 
at line 186, column 5

The ContentHandler interface

package org.xml.sax;


public interface ContentHandler {

    public void setDocumentLocator(Locator locator);
    
    public void startDocument() throws SAXException;
    
    public void endDocument() throws SAXException;
    
    public void startPrefixMapping(String prefix, String uri) 
     throws SAXException;

    public void endPrefixMapping(String prefix) throws SAXException;

    public void startElement(String namespaceURI, String localName,
         String qualifiedName, Attributes atts) throws SAXException;

    public void endElement(String namespaceURI, String localName,
     String qualifiedName) throws SAXException;

    public void characters(char[] text, int start, int length) 
     throws SAXException;

    public void ignorableWhitespace(char[] text, int start, int length)
     throws SAXException;

    public void processingInstruction(String target, String data)
     throws SAXException;

    public void skippedEntity(String name) throws SAXException;
     
}

SAX2 Event Reporter

import org.xml.sax.*;
import org.xml.sax.helpers.*;
import java.io.*;


public class EventReporter implements ContentHandler {

  public void setDocumentLocator(Locator locator) {}
  
  public void startDocument() throws SAXException {
    System.out.println("startDocument()"); 
  }

  public void endDocument() throws SAXException {
    System.out.println("endDocument()"); 
  }
  
  public void startElement(String namespaceURI, String localName, 
   String qualifiedName, Attributes atts) throws SAXException {
    namespaceURI = '"' + namespaceURI + '"';
    localName = '"' + localName + '"';
    qualifiedName = '"' + qualifiedName + '"';
    String attributeString = "{";
    for (int i = 0; i < atts.getLength(); i++) {
      attributeString += atts.getQName(i) + "=\"" + atts.getValue(i) + "\"";
      if (i != atts.getLength()-1) attributeString += ", ";
    }
    attributeString += "}";
    System.out.println("startElement(" + namespaceURI + ", " + localName + ", " 
    + qualifiedName + ", " + attributeString + ")"); 
  }
  
  public void endElement(String namespaceURI, String localName, String qualifiedName) 
   throws SAXException {
    namespaceURI = '"' + namespaceURI + '"';
    localName = '"' + localName + '"';
    qualifiedName = '"' + qualifiedName + '"';
    System.out.println("endElement(" + namespaceURI + ", " 
     + localName + ", " + qualifiedName + ")"); 
  }
  
  public void characters(char[] text, int start, int length) 
   throws SAXException {
    String textString = "[" + new String(text) + "]";
    System.out.println("characters(" + textString + ", " + start + ", " 
     +  length + ")"); 
  }
  
  public void ignorableWhitespace(char[] text, int start, int length)
   throws SAXException {
    System.out.println("ignorableWhitespace()"); 
  }
  
  public void processingInstruction(String target, String data)
   throws SAXException {
    System.out.println("processingInstruction(" + target + ", " 
     + data + ")"); 
  }

  public void startPrefixMapping(String prefix, String uri) 
   throws SAXException {
    System.out.println("startPrefixMapping(" + prefix + ", " 
     + uri + ")");         
  }
  
  public void endPrefixMapping(String prefix) throws SAXException {
    System.out.println("startPrefixMapping(" + prefix + ")");                 
  }

  public void skippedEntity(String name) throws SAXException {
    System.out.println("skippedEntity(" + name + ")");                         
  }

  // Could easily have put main() method in a separate class
  public static void main(String[] args) {
    
    XMLReader parser;
    try {
     parser = XMLReaderFactory.createXMLReader();
    }
    catch (Exception e) {
      // fall back on Xerces parser by name
      try {
        parser = XMLReaderFactory.createXMLReader(
         "org.apache.xerces.parsers.SAXParser");
      }
      catch (Exception ee) {
        System.err.println("Couldn't locate a SAX parser");
        return;          
      }
    }
     
    if (args.length == 0) {
      System.out.println(
       "Usage: java EventReporter URL1 URL2..."); 
    } 
      
    // Install the Document Handler      
    parser.setContentHandler(new EventReporter());
    
    // start parsing... 
    for (int i = 0; i < args.length; i++) {
      
      // command line should offer URIs or file names
      try {
        parser.parse(args[i]);
      }
      catch (SAXParseException e) { // well-formedness error
        System.out.println(args[i] + " is not well formed.");
        System.out.println(e.getMessage()
         + " at line " + e.getLineNumber() 
         + ", column " + e.getColumnNumber());
      }
      catch (SAXException e) { // some other kind of error
        System.out.println(e.getMessage());
      }
      catch (IOException e) {
        System.out.println("Could not report on " + args[i] 
         + " because of the IOException " + e);
      }
      
    }  
  
  }

}

Event Reporter Output

View in Browser

Questions?

A Sample Application

Full list

Goal: Return a list of all the URLs in this list as java.net.URL objects

Design Decisions

SAX Design

User Interface Class

import org.xml.sax.*;
import org.xml.sax.helpers.XMLReaderFactory;
import java.util.*;
import java.io.*;


public class WeblogsSAX {
     
  public static List listChannels() 
   throws IOException, SAXException {
    return listChannels(
     "http://static.userland.com/weblogMonitor/logs.xml"); 
  }
  
  public static List listChannels(String uri) 
   throws IOException, SAXException {
    
    XMLReader parser;
    try {
      parser = XMLReaderFactory.createXMLReader();
    }
    catch (SAXException ex) {
      parser = XMLReaderFactory.createXMLReader(
       "org.apache.xerces.parsers.SAXParser"
      );
    }
    Vector urls = new Vector(1000);
    ContentHandler handler = new URIGrabber(urls);
    parser.setContentHandler(handler);
    parser.parse(uri);
    return urls;
    
  }
  
  public static void main(String[] args) {
   
    try {
      List urls;
      if (args.length > 0) urls = listChannels(args[0]);
      else urls = listChannels();
      Iterator iterator = urls.iterator();
      while (iterator.hasNext()) {
        System.out.println(iterator.next()); 
      }
    }
    catch (IOException e) {
      System.err.println(e); 
    }
    catch (SAXParseException e) {
      System.err.println(e); 
      System.err.println("at line " + e.getLineNumber() 
       + ", column " + e.getColumnNumber()); 
    }
    catch (SAXException e) {
      System.err.println(e); 
    }
    catch (/* Unexpected */ Exception e) {
      e.printStackTrace(); 
    }
    
  }
  
}

ContentHandler Class

import org.xml.sax.*;
import java.net.*;
import java.util.Vector;

             // conflicts with java.net.ContentHandler
class URIGrabber implements org.xml.sax.ContentHandler {

  private Vector urls;

  URIGrabber(Vector urls) {
    this.urls = urls;
  }

  // do nothing methods
  public void setDocumentLocator(Locator locator) {}
  public void startDocument() throws SAXException {}
  public void endDocument() throws SAXException {}
  public void startPrefixMapping(String prefix, String uri)
   throws SAXException {}
  public void endPrefixMapping(String prefix) throws SAXException {}
  public void skippedEntity(String name) throws SAXException {}
  public void ignorableWhitespace(char[] text, int start, int length)
   throws SAXException {}
  public void processingInstruction(String target, String data)
   throws SAXException {}


  // Remember, there's no guarantee all the text of the
  // url element will be returned in a single call to characters
  private StringBuffer urlBuffer;
  private boolean collecting = false;

  public void startElement(String namespaceURI, String localName,
   String qualifiedName, Attributes atts) throws SAXException {

    if (qualifiedName.equals("url")) {
      collecting = true;
      urlBuffer = new StringBuffer();
    }

  }

  public void characters(char[] text, int start, int length)
   throws SAXException {

    if (collecting) {
      urlBuffer.append(text, start, length);
    }

  }

  public void endElement(String namespaceURI, String localName,
   String qualifiedName) throws SAXException {

    if (qualifiedName.equals("url")) {
      collecting = false;
      String url = urlBuffer.toString();
      try {
        urls.addElement(new URL(url));
      }
      catch (MalformedURLException e) {
        // skip this url
      }
    }

  }

}

Weblogs Output

% java Weblogs shortlogs.xml
http://www.mozillazine.org
http://www.salonherringwiredfool.com/
http://www.slashdot.org/

Features and Properties

Feature/Property SAXExceptions

SAXNotRecognizedException
the parser does not recognize a requested feature or property
SAXNotSupportedException
the parser does not support a requested feature/property or the feature/property is read-only

Required Features

Core Features

adapted from SAX2 documentation by David Megginson

Turning on Validation

Three Levels of Errors

In increasing order of severity:

  1. A warning; e.g. ambiguous content model, a constraint for compatibility

  2. A recoverable error: typically a validity error

  3. A fatal error: typically a well-formedness error

The ErrorHandler interface

package org.xml.sax;

public interface ErrorHandler {
 
  public void warning(SAXParseException exception)
   throws SAXException;

  public void error(SAXParseException exception)
   throws SAXException;
    
  public void fatalError(SAXParseException exception)
   throws SAXException;
    
}

An ErrorHandler for Reporting Validity Errors

import org.xml.sax.*;
import java.io.*;


public class ValidityErrorReporter implements ErrorHandler {
 
  Writer out;
 
  public ValidityErrorReporter(Writer out) {
    this.out = out;
  }
 
  public ValidityErrorReporter() {
    this(new OutputStreamWriter(System.out));
  }
 
  public void warning(SAXParseException ex)
   throws SAXException {

    try {
      out.write(ex.getMessage() + "\r\n");
      out.write(" at line " + ex.getLineNumber() + ", column " 
       + ex.getColumnNumber() + "\r\n");
      out.flush();
    }
    catch (IOException e) {
      throw new SAXException(e); 
    }
    
  }

  public void error(SAXParseException ex)
   throws SAXException {
    
    try {
      out.write(ex.getMessage() + "\r\n");
      out.write(" at line " + ex.getLineNumber() + ", column " 
       + ex.getColumnNumber() + "\r\n");
      out.flush();
    }
    catch (IOException e) {
      throw new SAXException(e); 
    }
    
  }
    
  public void fatalError(SAXParseException ex)
   throws SAXException {
    
    try {
      out.write(ex.getMessage() + "\r\n");
      out.write(" at line " + ex.getLineNumber() + ", column " 
       + ex.getColumnNumber() + "\r\n");
      out.flush();
    }
    catch (IOException e) {
      throw new SAXException(e); 
    }
    
  }
    
}

Validating

import org.xml.sax.*;
import org.xml.sax.helpers.*;
import org.apache.xerces.parsers.*; 
import java.io.*;


public class SAX2Validator {

  public static void main(String[] args) {
    
    XMLReader parser;
    try {
      parser = XMLReaderFactory.createXMLReader();
    }
    catch (SAXException ex) {
      try {
        parser = XMLReaderFactory.createXMLReader(
         "org.apache.xerces.parsers.SAXParser"
        );
      }
      catch (SAXException ex2) {
        System.err.println("Could not locate a SAX2 Parser");
        return;
      }
    }
     
    // turn on validation
    try {
      parser.setFeature(
       "http://xml.org/sax/features/validation", true);
      parser.setErrorHandler(new ValidityErrorReporter());
    }
    catch (SAXNotRecognizedException e) {
      System.err.println(
       "Installed XML parser cannot validate;"
       + " checking for well-formedness instead...");
    } 
    catch (SAXNotSupportedException e) {
      System.err.println(
       "Cannot turn on validation here; "
       + "checking for well-formedness instead...");
    } 
     
    if (args.length == 0) {
      System.out.println("Usage: java SAX2Validator URL1 URL2..."); 
    } 
      
    // start parsing... 
    for (int i = 0; i < args.length; i++) {
      
      // command line should offer URIs or file names
      try {
        parser.parse(args[i]);
        // If there are no well-formedness errors, 
        // then no exception is thrown
        System.out.println(args[i] + " is well formed.");
      }
      catch (SAXParseException e) { // well-formedness error
        System.out.println(args[i] + " is not well formed.");
        System.out.println(e.getMessage()
         + " at line " + e.getLineNumber() 
         + ", column " + e.getColumnNumber());
      }
      catch (SAXException e) { // some other kind of error
        System.out.println(e.getMessage());
      }
      catch (IOException e) {
        System.out.println("Could not check " + args[i] 
         + " because of the IOException " + e);
      }
      
    }  
  
  }

}

Core Properties

adapted from SAX2 documentation by David Megginson

Nonstandard Features in Xerces

Nonstandard Properties in Xerces

Properties for Extension Handlers

Handling Attributes in SAX2

Attributes Example

import org.xml.sax.*;
import org.apache.xerces.parsers.*;
import java.io.*;
import java.util.*;
import org.xml.sax.helpers.*;


public class XLinkSpider extends DefaultHandler {

  public static Enumeration listURIs(String systemId) 
   throws SAXException, IOException {
    
    // set up the parser 
    XMLReader parser;
    try {
      parser = XMLReaderFactory.createXMLReader();
    } 
    catch (SAXException e) {
      try {
        parser = XMLReaderFactory.createXMLReader(
         "org.apache.xerces.parsers.SAXParser");
      }
      catch (SAXException e2) {
        System.err.println("Error: could not locate a parser.");
        return null;
      }
    }
      
    // Install the Content Handler   
    XLinkSpider spider = new XLinkSpider();   
    parser.setContentHandler(spider);
    parser.parse(systemId);
    return spider.uris.elements();
      
  }
  
  private Vector uris = new Vector();

  public void startElement(String namespaceURI, String localName, 
   String rawName, Attributes atts) throws SAXException {
    
     String uri = atts.getValue(
      "http://www.w3.org/1999/xlink", "href");
     if (uri != null) uris.addElement(uri);
    
  }
  

  public static void main(String[] args) {
    
    if (args.length == 0) {
      System.out.println("Usage: java XLinkSpider URL1 URL2..."); 
    } 
      
    // start parsing... 
    for (int i = 0; i < args.length; i++) {
      
      try {
        Enumeration uris = listURIs(args[i]);
        while (uris.hasMoreElements()) {
          String s = (String) uris.nextElement();
          System.out.println(s);
        }
      }
      catch (Exception e) {
        System.err.println(e);
        e.printStackTrace(); 
      }
      
    } // end for
  
  } // end main

} // end XLinkSpider

Resolving Entities

EntityResolver Example

import org.xml.sax.*;

public class RSSResolver implements EntityResolver {

  public InputSource resolveEntity(String publicId, String systemId) {

    if ( publicId.equals(
          "-//Netscape Communications//DTD RSS 0.91//EN")
     || systemId.equals(
          "http://my.netscape.com/publish/formats/rss-0.91.dtd")) {
      return new InputSource(
       "http://metalab.unc.edu/xml/dtds/rss.dtd");
    } 
    else {
      // use the default behaviour
      return null;
    }
    
  }
   
}

Handling DTDs

DTDHandler Example

TextEntityReplacer

import org.xml.sax.*;
import java.util.*;
import java.net.*;
import java.io.*;


public class TextEntityReplacer implements DTDHandler {

  /* This class stores the notation and entity declarations 
     for a single document. It is not designed to be reused
     for multiple parses, though that would be straightforward
     extension. The public and system IDs of the document
     being parsed are set in the constructor.    
  */ 
  
  private URL systemID;
  private String publicID;
  
  public TextEntityReplacer(String publicID, String systemID) 
   throws MalformedURLException {
    System.err.println("created");
    this.publicID = publicID;
    this.systemID = new URL(systemID);
  }

  // store all notations in a hashtable. We'll need them later
  private Hashtable notations = new Hashtable();

  // for the DTDHandler interface
  public void notationDecl(String name, String publicID, String systemID)
   throws SAXException {
    
    Notation n = new Notation(name, publicID, systemID);
    notations.put(name, n);
    
  }
  
  private class Notation {
    
    String name;
    String publicID;
    String systemID;
    
    Notation(String name, String publicID, String systemID) {
      this.name = name;
      this.publicID = publicID;
      this.systemID = systemID;
    } 
    
  }
 
   
  // store all unparsed entities in a hashtable. We'll need them later
  private Hashtable unparsedEntities = new Hashtable();

  // for the DTDHandler interface
  public void unparsedEntityDecl(String name, String publicID, 
   String systemID, String notationName) throws SAXException {
    
    UnparsedEntity e = new UnparsedEntity(name, publicID, systemID, notationName);
    unparsedEntities.put(name, e);
    
  }    

  private class UnparsedEntity {
    
    String name;
    String publicID;
    String systemID;
    String notationName;
    
    UnparsedEntity(String name, String publicID, String systemID, String notationName) {
      this.name = name;
      this.notationName = notationName;
      this.publicID = publicID;
      this.systemID = systemID;
    } 
    
  }


  public boolean isText(String notationName) {
    
    Object o = notations.get(notationName);
    if (o == null) return false;
    Notation n = (Notation) o;
    if (n.systemID.startsWith("text/")) return true;
    return false;
    
  }
  
  public String getText(String entityName) throws IOException {
    
    Object o = unparsedEntities.get(entityName);
    if (o == null) return "";
    UnparsedEntity entity = (UnparsedEntity) o;
    if (!isText(entity.notationName)) {
      return " binary data "; // could throw an exception instead
    }
    
    URL source;
    try {
      source = new URL(systemID, entity.systemID);     
    }
    catch (Exception e) {
      return " unresolvable entity "; // could throw an exception instead
    }
    
    // I'm not really handling characetr encodings here. 
    // A more detailed look at the MIME type would allow that.
    Reader in = new BufferedReader(new InputStreamReader(source.openStream()));
    StringBuffer result = new StringBuffer();
    int c;
    while ((c = in.read()) != -1) {
      // Is this necessaary or will parser escape string automatically????
   /*   switch (c) {
        case '<': 
          result.append("&lt;");
          break;
        case '>': 
          result.append("&gt;");
          break;
        case '"': 
          result.append("&quot;");
          break;
        case '\'': 
          result.append("&apos;");
          break;
        case '&': 
          result.append("&amp;");
          break;
        default:
          result.append((char) c); 
      }*/
      result.append((char) c);
    }
    
    return result.toString();
    
  }

}

Handling Declarations

The DeclHandler interface:

package org.xml.sax.ext;

import org.xml.sax.SAXException;


public interface DeclHandler {

  public void elementDecl(String name, String model)
   throws SAXException;

  public void attributeDecl(String elementName, String attributeName, 
   String type, String defaultValue, String value) throws SAXException;

  public void internalEntityDecl(String name, String value)
   throws SAXException;

  public void externalEntityDecl(String name, String publicId,
   String systemId) throws SAXException;

}

Handling Lexical Events

The LexicalHandler interface

package org.xml.sax.ext;

import org.xml.sax.SAXException;


public interface LexicalHandler {

  public void startDTD(String name, String publicId, String systemId)
     throws SAXException;
  public void endDTD() throws SAXException;
  public void startEntity(String name) throws SAXException;
  public void endEntity(String name) throws SAXException;
  public void startCDATA() throws SAXException;
  public void endCDATA() throws SAXException;
  public void comment (char[] text, int start, int length) 
   throws SAXException;

}

LexicalHandler Example

import org.xml.sax.*;
import org.xml.sax.ext.*;
import org.xml.sax.helpers.*;
import java.io.IOException;


public class SAXCommentReader implements LexicalHandler {

  public void startDTD(String name, String publicId, String systemId)
   throws SAXException {}
  public void endDTD() throws SAXException {}
  public void startEntity(String name) throws SAXException {}
  public void endEntity(String name) throws SAXException {}
  public void startCDATA() throws SAXException {}
  public void endCDATA() throws SAXException {}

  public void comment (char[] text, int start, int length)
   throws SAXException {

    String comment = new String(text, start, length);
    System.out.println(comment);

  }

  public static void main(String[] args) {

    // set up the parser
    XMLReader parser;
    try {
      parser = XMLReaderFactory.createXMLReader();
    }
    catch (SAXException e) {
      try {
        parser = XMLReaderFactory.createXMLReader(
         "org.apache.xerces.parsers.SAXParser");
      }
      catch (SAXException e2) {
        System.err.println("Error: could not locate a parser.");
        return;
      }
    }

    // turn on comment handling
    try {
      parser.setProperty(
       "http://xml.org/sax/properties/lexical-handler",
       new SAXCommentReader()
      );
    }
    catch (SAXNotRecognizedException e) {
      System.err.println(
       "Installed XML parser does not provide lexical events...");
      return;
    }
    catch (SAXNotSupportedException e) {
      System.err.println(
       "Cannot turn on comment processing here");
      return;
    }

    if (args.length == 0) {
      System.out.println("Usage: java SAXCommentReader URL1 URL2...");
    }

    // start parsing...
    for (int i = 0; i < args.length; i++) {

      try {
        parser.parse(args[i]);
      }
      catch (SAXParseException e) { // well-formedness error
        System.out.println(args[i] + " is not well formed.");
        System.out.println(e.getMessage()
         + " at line " + e.getLineNumber()
         + ", column " + e.getColumnNumber());
      }
      catch (SAXException e) { // some other kind of error
        System.out.println(e.getMessage());
      }
      catch (IOException e) {
        System.out.println("Could not check " + args[i]
         + " because of the IOException " + e);
      }

    }

  }

}

SAXCommentReader Output 

J:\KENTUCKY\xmlandjava\EXAMPLES>java SAXCommentReader hotcop.xml
 This should be a four digit year like "1999",
     not a two-digit year like "99"
 The publisher is actually Polygram but I needed
       an example of a general entity reference.
 You can tell what album I was
     listening to when I wrote this example

Or try http://www.w3.org/TR/2000/REC-xml-20001006.xml

The Locator interface

Locator Example

import org.xml.sax.*;
import org.xml.sax.helpers.*;
import org.apache.xerces.parsers.*; 
import java.io.*;


public class LocationReporter implements ContentHandler {

  Locator locator = null;

  public void setDocumentLocator(Locator locator) {
    this.locator = locator;  
  }
  
  private String reportPosition() {
    
    if (locator != null) {
      
      String publicID = locator.getPublicId();
      String systemID = locator.getSystemId();
      int line        = locator.getLineNumber();
      int column      = locator.getColumnNumber();
      
      String name;
      if (publicID != null) name = publicID;
      else name = systemID;
      
      return " in " + name + " at line " + line 
       + ", column " + column;
    }
    return "";
    
  }
  
  public void startDocument() throws SAXException {
    System.out.println("Document started" + reportPosition()); 
  }

  public void endDocument() throws SAXException {
    System.out.println("Document ended" + reportPosition()); 
  }
  
  public void characters(char[] text, int start, int length) 
   throws SAXException {
    System.out.println("Got some characters" + reportPosition()); 
  }
  
  public void ignorableWhitespace(char[] text, int start, int length)
   throws SAXException {
    System.out.println("Got some ignorable white space" 
     + reportPosition()); 
  }
  
  public void processingInstruction(String target, String data)
   throws SAXException {
    System.out.println("Got a processing instruction" 
     + reportPosition()); 
  }
  
  // Changed methods for SAX2
  public void startElement(String namespaceURI, String localName,
	 String qualifiedName, Attributes atts) throws SAXException {
    System.out.println("Element " + qualifiedName + " started" 
     + reportPosition()); 
  }
  
  public void endElement(String namespaceURI, String localName,
	 String qualifiedName) throws SAXException {
    System.out.println("Element " + qualifiedName + " ended" 
     + reportPosition()); 
  } 

  // new methods for SAX2
  public void startPrefixMapping(String prefix, String uri) 
   throws SAXException {
    System.out.println("Started mapping prefix " + prefix 
     + " to URI " + uri + reportPosition());     
  }

  public void endPrefixMapping(String prefix) throws SAXException {
    System.out.println("Stopped mapping prefix " 
     + prefix + reportPosition());         
  }

  public void skippedEntity(String name) throws SAXException {
    System.out.println("Skipped entity " + name + reportPosition());         
  }  

  // Could easily have put main() method in a separate class
  public static void main(String[] args) {
    
    XMLReader parser;
    try {
      parser = XMLReaderFactory.createXMLReader();
    }
    catch (SAXException ex) {
      try {
        parser = XMLReaderFactory.createXMLReader(
         "org.apache.xerces.parsers.SAXParser");
      }
      catch (SAXException e2) {
        System.err.println("Error: no parser found!");
        return; 
      }
    }
     
    if (args.length == 0) {
      System.out.println(
       "Usage: java LocationReporter URL1 URL2..."); 
    } 
      
    // Install the Content Handler      
    parser.setContentHandler(new LocationReporter());
    
    // start parsing... 
    for (int i = 0; i < args.length; i++) {
      
      // command line should offer URIs or file names
      try {
        parser.parse(args[i]);
      }
      catch (SAXParseException e) { // well-formedness error
        System.out.println(args[i] + " is not well formed.");
        System.out.println(e.getMessage()
         + " at line " + e.getLineNumber() 
         + ", column " + e.getColumnNumber());
      }
      catch (SAXException e) { // some other kind of error
        System.out.println(e.getMessage());
      }
      catch (IOException e) {
        System.out.println("Could not report on " + args[i] 
         + " because of the IOException " + e);
      }
      
    }  
  
  }

}
View Output

Locator Example

Document started in file:///J:/KENTUCKY/xmlandjava/EXAMPLES/hotcop.xml at line 1, column 1
Got a processing instruction in file:///J:/KENTUCKY/xmlandjava/EXAMPLES/hotcop.xml at line 2, column 51
Started mapping prefix  to URI http://metalab.unc.edu/xml/namespace/song in file:///J:/KENTUCKY/xmlandjava/EXAMPLES/hotcop.xml at line 5, column 50
Started mapping prefix xlink to URI http://www.w3.org/1999/xlink in file:///J:/KENTUCKY/xmlandjava/EXAMPLES/hotcop.xml at line 5, column 50
Element SONG started in file:///J:/KENTUCKY/xmlandjava/EXAMPLES/hotcop.xml at line 5, column 50
Got some ignorable white space in file:///J:/KENTUCKY/xmlandjava/EXAMPLES/hotcop.xml at line 6, column 3
Element TITLE started in file:///J:/KENTUCKY/xmlandjava/EXAMPLES/hotcop.xml at line 6, column 10
Got some characters in file:///J:/KENTUCKY/xmlandjava/EXAMPLES/hotcop.xml at line 6, column 17
Element TITLE ended in file:///J:/KENTUCKY/xmlandjava/EXAMPLES/hotcop.xml at line 6, column 26
Got some ignorable white space in file:///J:/KENTUCKY/xmlandjava/EXAMPLES/hotcop.xml at line 7, column 3
Element PHOTO started in file:///J:/KENTUCKY/xmlandjava/EXAMPLES/hotcop.xml at line 9, column 65
Element PHOTO ended in file:///J:/KENTUCKY/xmlandjava/EXAMPLES/hotcop.xml at line 9, column 65
Got some ignorable white space in file:///J:/KENTUCKY/xmlandjava/EXAMPLES/hotcop.xml at line 10, column 3
Element COMPOSER started in file:///J:/KENTUCKY/xmlandjava/EXAMPLES/hotcop.xml at line 10, column 13
Got some characters in file:///J:/KENTUCKY/xmlandjava/EXAMPLES/hotcop.xml at line 10, column 27
Element COMPOSER ended in file:///J:/KENTUCKY/xmlandjava/EXAMPLES/hotcop.xml at line 10, column 39
Got some ignorable white space in file:///J:/KENTUCKY/xmlandjava/EXAMPLES/hotcop.xml at line 11, column 3
Element COMPOSER started in file:///J:/KENTUCKY/xmlandjava/EXAMPLES/hotcop.xml at line 11, column 13
Got some characters in file:///J:/KENTUCKY/xmlandjava/EXAMPLES/hotcop.xml at line 11, column 25
Element COMPOSER ended in file:///J:/KENTUCKY/xmlandjava/EXAMPLES/hotcop.xml at line 11, column 37
Got some ignorable white space in file:///J:/KENTUCKY/xmlandjava/EXAMPLES/hotcop.xml at line 12, column 3
Element COMPOSER started in file:///J:/KENTUCKY/xmlandjava/EXAMPLES/hotcop.xml at line 12, column 13
Got some characters in file:///J:/KENTUCKY/xmlandjava/EXAMPLES/hotcop.xml at line 12, column 26
Element COMPOSER ended in file:///J:/KENTUCKY/xmlandjava/EXAMPLES/hotcop.xml at line 12, column 38
Got some ignorable white space in file:///J:/KENTUCKY/xmlandjava/EXAMPLES/hotcop.xml at line 13, column 3
Element PRODUCER started in file:///J:/KENTUCKY/xmlandjava/EXAMPLES/hotcop.xml at line 13, column 13
Got some characters in file:///J:/KENTUCKY/xmlandjava/EXAMPLES/hotcop.xml at line 13, column 27
Element PRODUCER ended in file:///J:/KENTUCKY/xmlandjava/EXAMPLES/hotcop.xml at line 13, column 39
Got some ignorable white space in file:///J:/KENTUCKY/xmlandjava/EXAMPLES/hotcop.xml at line 14, column 3
Got some ignorable white space in file:///J:/KENTUCKY/xmlandjava/EXAMPLES/hotcop.xml at line 16, column 3
Element PUBLISHER started in file:///J:/KENTUCKY/xmlandjava/EXAMPLES/hotcop.xml at line 16, column 73
Got some characters in file:///J:/KENTUCKY/xmlandjava/EXAMPLES/hotcop.xml at line 17, column 7
Got some characters in file:///J:/KENTUCKY/xmlandjava/EXAMPLES/hotcop.xml at line 17, column 12
Got some characters in file:///J:/KENTUCKY/xmlandjava/EXAMPLES/hotcop.xml at line 18, column 3
Element PUBLISHER ended in file:///J:/KENTUCKY/xmlandjava/EXAMPLES/hotcop.xml at line 18, column 16
Got some ignorable white space in file:///J:/KENTUCKY/xmlandjava/EXAMPLES/hotcop.xml at line 19, column 3
Element LENGTH started in file:///J:/KENTUCKY/xmlandjava/EXAMPLES/hotcop.xml at line 19, column 11
Got some characters in file:///J:/KENTUCKY/xmlandjava/EXAMPLES/hotcop.xml at line 19, column 15
Element LENGTH ended in file:///J:/KENTUCKY/xmlandjava/EXAMPLES/hotcop.xml at line 19, column 25
Got some ignorable white space in file:///J:/KENTUCKY/xmlandjava/EXAMPLES/hotcop.xml at line 20, column 3
Element YEAR started in file:///J:/KENTUCKY/xmlandjava/EXAMPLES/hotcop.xml at line 20, column 9
Got some characters in file:///J:/KENTUCKY/xmlandjava/EXAMPLES/hotcop.xml at line 20, column 13
Element YEAR ended in file:///J:/KENTUCKY/xmlandjava/EXAMPLES/hotcop.xml at line 20, column 21
Got some ignorable white space in file:///J:/KENTUCKY/xmlandjava/EXAMPLES/hotcop.xml at line 21, column 3
Element ARTIST started in file:///J:/KENTUCKY/xmlandjava/EXAMPLES/hotcop.xml at line 21, column 11
Got some characters in file:///J:/KENTUCKY/xmlandjava/EXAMPLES/hotcop.xml at line 21, column 25
Element ARTIST ended in file:///J:/KENTUCKY/xmlandjava/EXAMPLES/hotcop.xml at line 21, column 35
Got some ignorable white space in file:///J:/KENTUCKY/xmlandjava/EXAMPLES/hotcop.xml at line 22, column 1
Element SONG ended in file:///J:/KENTUCKY/xmlandjava/EXAMPLES/hotcop.xml at line 22, column 9
Stopped mapping prefix xlink in file:///J:/KENTUCKY/xmlandjava/EXAMPLES/hotcop.xml at line 22, column 9
Stopped mapping prefix  in file:///J:/KENTUCKY/xmlandjava/EXAMPLES/hotcop.xml at line 22, column 9
Document ended in Null Entity at line -1, column -1

The DefaultHandler class

The NamespaceSupport class

Filtering XML

XMLFilter Example

import org.xml.sax.*;
import org.xml.sax.helpers.*;
import java.util.*;
import java.io.IOException;


public class UnparsedTextFilter extends XMLFilterImpl {

  private TextEntityReplacer replacer;

  public UnparsedTextFilter(XMLReader parent) {
    super(parent);
    System.err.println("created UnparsedTextFilter");
  }

  public void parse(InputSource input) 
   throws IOException, SAXException {
    System.err.println("parsing");
    replacer = new TextEntityReplacer(input.getPublicId(), 
     input.getSystemId());
    this.setDTDHandler(replacer); 
  }
  // The other parse() method just calls this one 

  public void parse(String systemId) 
   throws IOException, SAXException {
    parse(new InputSource(systemId)); 
  }

  public void startElement(String uri, String localName, 
   String qualifiedName, Attributes attributes) throws SAXException {
    
    Vector extraText = new Vector();

    // Are there any unparsed entities in the attributes?
    for (int i = 0; i < attributes.getLength(); i++) {
      if (attributes.getType(i).equals("ENTITY")) {
        try {
          System.out.println("replacing");
          String s = replacer.getText(attributes.getValue(i));
          if (s != null) extraText.addElement(s);
        }
        catch (IOException e) {
          System.err.println(e); 
        }
      } 
      
    }    

    super.startElement(uri, localName, qualifiedName, attributes);
    
    // Now spew out the values of the unparsed entities:
    Enumeration e = extraText.elements();
    while (e.hasMoreElements()) {
      Object o = e.nextElement();
      String s = (String) o;
      super.characters(s.toCharArray(), 0, s.length()); 
    }
    
  }

}

TextMerger

import org.xml.sax.*;
import org.xml.sax.helpers.*;
import java.util.*;
import java.io.IOException;
import org.apache.xml.serialize.*;


public class TextMerger {

  public static void main(String[] args) {
  
    XMLReader base;
    try {
     base = XMLReaderFactory.createXMLReader();
    }
    catch (Exception e) {
      // fall back on Xerces parser by name
      try {
        base = XMLReaderFactory.createXMLReader(
         "org.apache.xerces.parsers.SAXParser");
      }
      catch (Exception ee) {
        System.err.println("Couldn't locate a SAX parser");
        return;          
      }
    }
    
    XMLReader parser = new UnparsedTextFilter(base);
    
    //essentially a pretty printer
    XMLSerializer printer 
     = new XMLSerializer(System.out, new OutputFormat());
    
    parser.setContentHandler(printer);
    
    for (int i = 0; i < args.length; i++) {
      try {
        parser.parse(args[i]);
      }
      catch (SAXParseException e) { // well-formedness error
        System.out.println(args[i] + " is not well formed.");
        System.out.println(e.getMessage()
         + " at line " + e.getLineNumber() 
         + ", column " + e.getColumnNumber());
      }
      catch (SAXException e) { // some other kind of error
        System.out.println(e.getMessage());
      }
      catch (IOException e) {
        System.out.println("Could not report on " + args[i] 
         + " because of the IOException " + e);
      }      
    }
  
  }

}

InputSource

The InputSource interface

package org.xml.sax;

import java.io.*;

public class InputSource {

  public InputSource() 
  public InputSource(String systemID) 
  public InputSource(InputStream in)
  public InputSource(Reader in)

  public void   setPublicId(String publicID)
  public String getPublicId()
  public void   setSystemId(String systemID)
  public String getSystemId()

  public void        setByteStream(InputStream byteStream)
  public InputStream getByteStream()
  public void        setEncoding(String encoding)
  public String      getEncoding()
  public void        setCharacterStream(Reader characterStream)
  public Reader      getCharacterStream()

}

Example of InputSource

import org.xml.sax;
import java.io.*;
import java.net.*;
import java.util.zip.*;
...
try {

  URL u = new URL(
   "http://metalab.unc.edu/xml/examples/1998validstats.xml.gz"); 
  InputStream raw = u.openStream();
  InputStream decompressed = new GZIPInputStream(in);
  InputSource in = new InputSource(decompressed);
  // read the document... 

}
catch (IOException e) {
  System.err.println(e);
}
catch (SAXException e) {
  System.err.println(e);
}

What SAX2 doesn't do

Event Based API Caveats

To Learn More


Questions?

Part IV: DOM, The Document Object Model

Trees

Document Object Model

DOM Evolution

DOM Parsers for Java

Eight Modules:

Which modules and features are supported?

Which modules are supported?

import org.apache.xerces.dom.*;
import org.w3c.dom.*;
import org.xml.sax.*;
import java.io.*;


public class ModuleChecker {

  public static void main(String[] args) {
     
    // parser dependent
    DOMImplementation implementation 
     = DOMImplementationImpl.getDOMImplementation();
    String[] features = {"XML", "HTML", "Views", "StyleSheets",
     "CSS", "CSS2", "Events", "UIEvents", "MouseEvents", 
     "MutationEvents", "HTMLEvents", "Traversal", "Range"};
    
    for (int i = 0; i < features.length; i++) {
      if (implementation.hasFeature(features[i], "2.0")) {
        System.out.println("Implementation supports " 
         + features[i]);
      } 
      else {
        System.out.println("Implementation does not support " 
         + features[i]);
      } 
    }
  
  }

}

Which modules are supported? Results

% java ModuleChecker
Implementation supports XML
Implementation does not support HTML
Implementation does not support Views
Implementation does not support StyleSheets
Implementation does not support CSS
Implementation does not support CSS2
Implementation supports Events
Implementation does not support UIEvents
Implementation does not support MouseEvents
Implementation supports MutationEvents
Implementation does not support HTMLEvents
Implementation supports Traversal
Implementation does not support Range

DOM Trees

org.w3c.dom

The DOM Process

  1. Library specific code creates a parser

  2. The parser parses the document and returns a DOM org.w3c.dom.Document object.

  3. The entire document is stored in memory.

  4. DOM methods and interfaces are used to extract data from this object

Parsing documents with a DOM Parser Example 

import org.apache.xerces.parsers.*;
import org.w3c.dom.*;
import org.xml.sax.*;
import java.io.*;

public class DOMParserMaker {

  public static void main(String[] args) {
     
    // This is simpler but less flexible than the SAX approach.
    // Perhaps a good creational design pattern is needed here?   
  
    DOMParser parser = new DOMParser();
    
    for (int i = 0; i < args.length; i++) {
      try {
        // Read the entire document into memory
        parser.parse(args[i]); 
       
        Document d = parser.getDocument();
        // work with the document...
      }
      catch (SAXException e) {
        System.err.println(e); 
      }
      catch (IOException e) {
        System.err.println(e); 
      }
      
    }
   
  }

}

The Node Interface 

package org.w3c.dom;

public interface Node {

  // NodeType
  public static final short ELEMENT_NODE                = 1;
  public static final short ATTRIBUTE_NODE              = 2;
  public static final short TEXT_NODE                   = 3;
  public static final short CDATA_SECTION_NODE          = 4;
  public static final short ENTITY_REFERENCE_NODE       = 5;
  public static final short ENTITY_NODE                 = 6;
  public static final short PROCESSING_INSTRUCTION_NODE = 7;
  public static final short COMMENT_NODE                = 8;
  public static final short DOCUMENT_NODE               = 9;
  public static final short DOCUMENT_TYPE_NODE          = 10;
  public static final short DOCUMENT_FRAGMENT_NODE      = 11;
  public static final short NOTATION_NODE               = 12;

  public String       getNodeName();
  public String       getNodeValue() throws DOMException;
  public void         setNodeValue(String nodeValue) throws DOMException;
  public short        getNodeType();
  public Node         getParentNode();
  public NodeList     getChildNodes();
  public Node         getFirstChild();
  public Node         getLastChild();
  public Node         getPreviousSibling();
  public Node         getNextSibling();
  public NamedNodeMap getAttributes();
  public Document     getOwnerDocument();
  public Node         insertBefore(Node newChild, Node refChild) throws DOMException;
  public Node         replaceChild(Node newChild, Node oldChild) throws DOMException;
  public Node         removeChild(Node oldChild) throws DOMException;
  public Node         appendChild(Node newChild) throws DOMException;
  public boolean      hasChildNodes();
  public Node         cloneNode(boolean deep);
  public void         normalize();
  public boolean      supports(String feature, String version);
  public String       getNamespaceURI();
  public String       getPrefix();
  public void         setPrefix(String prefix) throws DOMException;
  public String       getLocalName();
}

The NodeList Interface 

package org.w3c.dom;

public interface NodeList {
  public Node item(int index);
  public int  getLength();
}

Now we're really ready to read a document

Node Reporter

import org.apache.xerces.parsers.*;
import org.w3c.dom.*;
import org.xml.sax.*;
import java.io.*;


public class NodeReporter {

  public static void main(String[] args) {
     
    DOMParser parser = new DOMParser();
    NodeReporter iterator = new NodeReporter();
    
    for (int i = 0; i < args.length; i++) {
      try {
        // Read the entire document into memory
        parser.parse(args[i]); 
       
        Document doc = parser.getDocument();
        iterator.followNode(doc);
      }
      catch (SAXException e) {
        System.err.println(e); 
      }
      catch (IOException e) {
        System.err.println(e); 
      }
      
    }
  
  } // end main

  // note use of recursion
  public void followNode(Node node) {
    
    processNode(node);
    if (node.hasChildNodes()) {
      NodeList children = node.getChildNodes();
      for (int i = 0; i < children.getLength(); i++) {
        followNode(children.item(i));
      } 
    }
    
  }

  public void processNode(Node node) {
    
    String name = node.getNodeName();
    String type = getTypeName(node.getNodeType());
    System.out.println("Type " + type + ": " + name);
    
  }
  
  public static String getTypeName(int type) {
    
    switch (type) {
      case Node.ELEMENT_NODE: return "Element";
      case Node.ATTRIBUTE_NODE: return "Attribute";
      case Node.TEXT_NODE: return "Text";
      case Node.CDATA_SECTION_NODE: return "CDATA Section";
      case Node.ENTITY_REFERENCE_NODE: return "Entity Reference";
      case Node.ENTITY_NODE: return "Entity";
      case Node.PROCESSING_INSTRUCTION_NODE: return "Processing Instruction";
      case Node.COMMENT_NODE : return "Comment";
      case Node.DOCUMENT_NODE: return "Document";
      case Node.DOCUMENT_TYPE_NODE: return "Document Type Declaration";
      case Node.DOCUMENT_FRAGMENT_NODE: return "Document Fragment";
      case Node.NOTATION_NODE: return "Notation";
      default: return "Unknown Type"; 
    }
    
  }

}

Node Reporter Output

% java NodeReporter hotcop.xml
Type Document: #document
Type Processing Instruction: xml-stylesheet
Type Document Type Declaration: SONG
Type Element: SONG
Type Text: #text
Type Element: TITLE
Type Text: #text
Type Text: #text
Type Element: PHOTO
Type Text: #text
Type Element: COMPOSER
Type Text: #text
Type Text: #text
Type Element: COMPOSER
Type Text: #text
Type Text: #text
Type Element: COMPOSER
Type Text: #text
Type Text: #text
Type Element: PRODUCER
Type Text: #text
Type Text: #text
Type Comment: #comment
Type Text: #text
Type Element: PUBLISHER
Type Text: #text
Type Text: #text
Type Element: LENGTH
Type Text: #text
Type Text: #text
Type Element: YEAR
Type Text: #text
Type Text: #text
Type Element: ARTIST
Type Text: #text
Type Text: #text
Type Comment: #comment

Attributes are missing from this output. They are not nodes. They are properties of nodes.

Node Values as returned by getNodeValue()

Node TypeNode Value
element nodenull
attribute nodeattribute value
text nodetext of the node
CDATA section nodetext of the section
entity reference nodenull
entity nodenull
processing instruction nodecontent of the processing instruction, not including the target
comment nodetext of the comment
document nodenull
document type declaration nodenull
document fragment nodenull
notation nodenull

The Document Node

The Document Interface 

package org.w3c.dom;

  public interface Document extends Node {
  
    public DocumentType      getDoctype();
    public DOMImplementation getImplementation();
    public Element           getDocumentElement();
    public Element           createElement(String tagName) throws DOMException;
    public Element           createElementNS(String namespaceURI, String qualifiedName) throws DOMException;
    public DocumentFragment  createDocumentFragment();
    public Text              createTextNode(String data);
    public Comment           createComment(String data);
    public CDATASection      createCDATASection(String data) throws DOMException;
    public ProcessingInstruction createProcessingInstruction(String target, String data)
     throws DOMException;
    public Attr            createAttribute(String name) throws DOMException;
    public Attr            createAttributeNS(String namespaceURI, String qualifiedName) throws DOMException;
    public EntityReference createEntityReference(String name) throws DOMException;
    public NodeList        getElementsByTagName(String tagname);
    public NodeList        getElementsByTagNameNS(String namespaceURI, String localName);
    public Element         getElementById(String elementId);
    public Node            importNode(Node importedNode, boolean deep) throws DOMException;
    
}

A Sample Application

Full list

DOM Design

Weblogs with DOM

import org.w3c.dom.*;
import org.xml.sax.SAXException;
import java.io.IOException;
import java.util.*;
import java.net.*;


public class WeblogsDOM {

  public static String DEFAULT_URL
   = "http://static.userland.com/weblogMonitor/logs.xml";

  public static List listChannels() throws DOMException {
    return listChannels(DEFAULT_URL);
  }

  public static List listChannels(String uri) throws DOMException {

    if (uri == null) {
      throw new NullPointerException("URL must be non-null");
    }

    org.apache.xerces.parsers.DOMParser parser
     = new org.apache.xerces.parsers.DOMParser();

    Vector urls = null;

    try {
      // Read the entire document into memory
      parser.parse(uri);
      Document doc = parser.getDocument();
      NodeList logs = doc.getElementsByTagName("url");

      urls = new Vector(logs.getLength());

      for (int i = 0; i < logs.getLength(); i++) {
        try {
          Node element = logs.item(i);
          Node text = element.getFirstChild();
          String content = text.getNodeValue();
          URL u = new URL(content);
          urls.addElement(u);
        }
        catch (MalformedURLException e) {
          // bad input data from one third party; just ignore it
        }
      }
    }
    catch (SAXException e) {
      System.err.println(e);
    }
    catch (IOException e) {
      System.err.println(e);
    }

    return urls;

  }

  public static void main(String[] args) {

    try {
      List urls;
      if (args.length > 0) {
        try {
          URL url = new URL(args[0]);
          urls = listChannels(args[0]);
        }
        catch (MalformedURLException e) {
          System.err.println("Usage: java WeblogsDOM url");
          return;
        }
      }
      else {
        urls = listChannels();
      }
      Iterator iterator = urls.iterator();
      while (iterator.hasNext()) {
        System.out.println(iterator.next());
      }
    }
    catch (/* Unexpected */ Exception e) {
      e.printStackTrace();
    }

  } // end main

}

Weblogs Output

% java WeblogsDOM
http://2020Hindsight.editthispage.com/
http://www.sff.net/people/mitchw/weblog/weblog.htp
http://nate.weblogs.com/
http://plugins.launchpoint.net
http://404.psistorm.net
http://home.att.net/~geek9000
http://daubnet.tzo.com/weblog
several hundred more...

Element Nodes

The Element Interface

package org.w3c.dom;

public interface Element extends Node {

  public String    getTagName();

  public NodeList  getElementsByTagName(String name);
  public NodeList  getElementsByTagNameNS(String namespaceURI, String localName);

  public String    getAttribute(String name);
  public String    getAttributeNS(String namespaceURI, String localName);
  public void      setAttribute(String name, String value) throws DOMException;
  public void      setAttributeNS(String namespaceURI, String qualifiedName, String value) throws DOMException;
  public void      removeAttribute(String name) throws DOMException;
  public void      removeAttributeNS(String namespaceURI, String localName) throws DOMException;
  public Attr      getAttributeNode(String name);
  public Attr      getAttributeNodeNS(String namespaceURI, String localName);
  public Attr      setAttributeNode(Attr newAttr) throws DOMException;
  public Attr      setAttributeNodeNS(Attr newAttr) throws DOMException;
  public Attr      removeAttributeNode(Attr oldAttr) throws DOMException;

}

IDTagger

import org.apache.xerces.parsers.DOMParser;
import org.w3c.dom.*;
import org.xml.sax.*;
import java.io.IOException;
import org.apache.xml.serialize.*;


public class IDTagger {

  int id = 1;

  public void processNode(Node node) {
    
    if (node instanceof Element) {
      
      Element element = (Element) node;
      String currentID = element.getAttribute("ID");
      if (currentID == null || currentID.equals("")) {
        element.setAttribute("ID", "_" + id);
        id = id + 1; 
      }
    }
    
  }

  // note use of recursion
  public void followNode(Node node) {
    
    processNode(node);
    if (node.hasChildNodes()) {
      NodeList children = node.getChildNodes();
      for (int i = 0; i < children.getLength(); i++) {
        followNode(children.item(i));
      } 
    }
    
  }

  public static void main(String[] args) {
     
    DOMParser parser  = new DOMParser();
    IDTagger iterator = new IDTagger();
    
    for (int i = 0; i < args.length; i++) {
      try {
        // Read the entire document into memory
        parser.parse(args[i]); 
       
        Document document = parser.getDocument();
        iterator.followNode(document);
        
        // now we serialize the document...
        OutputFormat format = new OutputFormat(document);
        XMLSerializer serializer 
         = new XMLSerializer(System.out, format);
        serializer.serialize(document);       
        
      }
      catch (SAXException e) {
        System.err.println(e); 
      }
      catch (IOException e) {
        System.err.println(e); 
      }
      
    }
  
  } // end main

}

Output from IDTagger

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE SONG SYSTEM "song.dtd">
<?xml-stylesheet type="text/css" href="song.css"?>
<SONG ID="_1" xmlns="http://metalab.unc.edu/xml/namespace/song"
xmlns:xlink="http://www.w3.org/1999/xlink">   <TITLE ID="_2">Hot
Cop</TITLE>   <PHOTO ALT="Victor Willis in Cop Outfit" HEIGHT="200"
ID="_3" WIDTH="100" xlink:href="hotcop.jpg" xlink:show="onLoad"
xlink:type="simple"/>   <COMPOSER ID="_4">Jacques Morali</COMPOSER>
<COMPOSER ID="_5">Henri Belolo</COMPOSER>   <COMPOSER ID="_6">Victor
Willis</COMPOSER>   <PRODUCER ID="_7">Jacques Morali</PRODUCER>   <!--
The publisher is actually Polygram but I needed         an example of a
general entity reference. -->   <PUBLISHER ID="_8"
xlink:href="http://www.amrecords.com/" xlink:type="simple">     A &amp;
M Records   </PUBLISHER>   <LENGTH ID="_9">6:20</LENGTH>   <YEAR
ID="_10">1978</YEAR>   <ARTIST ID="_11">Village People</ARTIST> </SONG>
<!-- You can tell what album I was 
     listening to when I wrote this example -->
View Output in Browser

CharacterData interface

The CharacterData Interface

package org.w3c.dom;

public interface CharacterData extends Node {

  public String  getData() throws DOMException;
  public void    setData(String data) throws DOMException;
  public int     getLength();
  public String  substringData(int offset, int count) throws DOMException;
  public void    appendData(String arg) throws DOMException;
  public void    insertData(int offset, String arg) throws DOMException;
  public void    deleteData(int offset, int count) throws DOMException;
  public void    replaceData(int offset, int count, String arg) throws DOMException;
  
}

ROT13 XML Text

import org.apache.xerces.parsers.DOMParser;
import org.apache.xml.serialize.*;
import org.w3c.dom.*;
import org.xml.sax.SAXException;
import java.io.IOException;


public class ROT13XML {

  public void processNode(Node node) {
    
    if (node instanceof CharacterData) {
      CharacterData text = (CharacterData) node;
      String data = text.getData();
      text.setData(rot13(data));
    }
    
  }

  // note use of recursion
  public void followNode(Node node) {
    
    processNode(node);
    if (node.hasChildNodes()) {
      NodeList children = node.getChildNodes();
      for (int i = 0; i < children.getLength(); i++) {
        followNode(children.item(i));
      } 
    }
    
  }
  
  public static String rot13(String s) {
    
    StringBuffer result = new StringBuffer(s.length());
    for (int i = 0; i < s.length(); i++) {
      int c = s.charAt(i);
      if (c >= 'A' && c <= 'M') result.append((char) (c+13));
      else if (c >= 'N' && c <= 'Z') result.append((char) (c-13));
      else if (c >= 'a' && c <= 'm') result.append((char) (c+13));
      else if (c >= 'n' && c <= 'z') result.append((char) (c-13));
      else result.append((char) c);
      
    } 
    return result.toString();
    
  }

  public static void main(String[] args) {
     
    DOMParser parser   = new DOMParser();
    ROT13XML  iterator = new ROT13XML();
    
    for (int i = 0; i < args.length; i++) {
      try {
        // Read the entire document into memory
        parser.parse(args[i]); 
       
        Document document = parser.getDocument();
        iterator.followNode(document);
        
        // now we serialize the document...
        OutputFormat format = new OutputFormat(document);
        XMLSerializer serializer 
         = new XMLSerializer(System.out, format);
        serializer.serialize(document);
               
      }
      catch (SAXException e) {
        System.err.println(e); 
      }
      catch (IOException e) {
        System.err.println(e); 
      }
      
    }
  
  } // end main

}

ROT13 XML Output

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE SONG SYSTEM "song.dtd">
<?xml-stylesheet type="text/css" href="song.css"?>
<SONG xmlns="http://metalab.unc.edu/xml/namespace/song"
xmlns:xlink="http://www.w3.org/1999/xlink">   <TITLE>Ubg Pbc</TITLE>
<PHOTO ALT="Victor Willis in Cop Outfit" HEIGHT="200" WIDTH="100"
xlink:href="hotcop.jpg" xlink:show="onLoad" xlink:type="simple"/>
<COMPOSER>Wnpdhrf Zbenyv</COMPOSER>   <COMPOSER>Uraev Orybyb</COMPOSER>
<COMPOSER>Ivpgbe Jvyyvf</COMPOSER>   <PRODUCER>Wnpdhrf Zbenyv</PRODUCER>
<!-- Gur choyvfure vf npghnyyl Cbyltenz ohg V arrqrq         na rknzcyr
bs n trareny ragvgl ersrerapr. -->   <PUBLISHER
xlink:href="http://www.amrecords.com/" xlink:type="simple">     N &amp;
Z Erpbeqf   </PUBLISHER>   <LENGTH>6:20</LENGTH>   <YEAR>1978</YEAR>
<ARTIST>Ivyyntr Crbcyr</ARTIST> </SONG>
<!-- Lbh pna gryy jung nyohz V jnf 
     yvfgravat gb jura V jebgr guvf rknzcyr -->

Text Nodes

The Text Interface

package org.w3c.dom;

public interface Text extends CharacterData {

  public Text splitText(int offset) throws DOMException;
  
}

CDATA section Nodes

The CDATASection Interface

package org.w3c.dom;

public interface CDATASection extends Text {
}

DocumentType Nodes

The DocumentType Interface

package org.w3c.dom;

public interface DocumentType extends Node {

  public String       getName();
  public NamedNodeMap getEntities();
  public NamedNodeMap getNotations();
  public String       getPublicId();
  public String       getSystemId();
  public String       getInternalSubset();
  
}

Example of the DocumentType Interface

XHTMLValidator

import org.w3c.dom.*;
import org.apache.xerces.parsers.*; 
import java.io.*;
import org.xml.sax.*;


public class XHTMLValidator {

  public static void main(String[] args) {
    
    for (int i = 0; i < args.length; i++) {
      validate(args[i]);
    }   
    
  }

  private static DOMParser parser = new DOMParser();
  
  static {
    
    // turn on validation
    try {
      parser.setFeature(
       "http://xml.org/sax/features/validation", true);
      parser.setErrorHandler(new ValidityErrorReporter());
    }
    catch (SAXNotRecognizedException e) {
      System.err.println(
         "Installed XML parser cannot validate; "
       + "checking for well-formedness instead...");
    } 
    catch (SAXNotSupportedException e) {
      System.err.println(
       "Cannot turn on validation here; "
       + " checking for well-formedness instead...");
    }     
    
  }
  
  // not thread safe
  public static void validate(String source) {
        
    try {

      try {
        parser.parse(source); 
        // ValidityErrorReporter prints any validity errors detected
      }
      catch (SAXException e) {  
        System.out.println(source + " is not well formed."); 
        return; 
      }
      
      // If we get this far, then the document is well-formed XML.
      // Check to see whether the document is actually XHTML    
      Document document = parser.getDocument();
    
      DocumentType doctype = document.getDoctype();
    
      if (doctype == null) {
        System.out.println("No DOCTYPE"); 
        return;
      }

      String name     = doctype.getName();
      String systemID = doctype.getSystemId();
      String publicID = doctype.getPublicId();
      
      if (!name.equals("html")) {
        System.out.println("Incorrect root element name " + name); 
      }
    
      if (publicID == null
       || (!publicID.equals("-//W3C//DTD XHTML 1.0 Strict//EN")
           && !publicID.equals(
                "-//W3C//DTD XHTML 1.0 Transitional//EN")
           && !publicID.equals(
                "-//W3C//DTD XHTML 1.0 Frameset//EN"))) {
        System.out.println(source 
         + " does not seem to use an XHTML 1.0 DTD");
      }
    
      // Check the namespace on the root element
      Element root = document.getDocumentElement();
      String xmlnsValue = root.getAttribute("xmlns");
      if (!xmlnsValue.equals("http://www.w3.org/1999/xhtml")) {
        System.out.println(source 
         + " does not properly declare the"
         + " http://www.w3.org/1999/xhtml"
         + " namespace on the root element");        
      }
    
      // get ready for the next parse
      parser.reset();
      
    }
    catch (IOException e) {
      System.err.println("Could not read " + source);
    }
    catch (Exception e) {
      System.err.println(e);
      e.printStackTrace();
    }
    
  }

}

EntityReference Nodes

The EntityReference Interface

package org.w3c.dom;

public interface EntityReference extends Node {

}

Attr Nodes

The Attr Interface

package org.w3c.dom;

public interface Attr extends Node {

  public String   getName();
  public boolean  getSpecified();
  public String   getValue();
  public void     setValue(String value) throws DOMException;
  public Element  getOwnerElement();
  
}

XLinkSpider with DOM

import org.xml.sax.*;
import org.apache.xerces.parsers.*;
import java.io.*;
import java.util.*;
import org.w3c.dom.*;


public class DOMSpider {

  private static DOMParser parser = new DOMParser();
  
  // namespace suport is turned off by default in Xerces
  static {
    try {
      parser.setFeature(
       "http://xml.org/sax/features/namespaces", true); 
    }
    catch (Exception e) {
      System.err.println(e);
    }
  }
  
  private static Vector visited = new Vector();
  
  private static int maxDepth = 5;
  private static int currentDepth = 0; 
  
  public static void listURIs(String systemId) {
    
    currentDepth++;
    try {
      if (currentDepth < maxDepth) {
        parser.parse(systemId);
     
        Document document = parser.getDocument();   
    
        Vector uris = new Vector();
        // search the document for uris, 
        // store them in vector, and print them
        searchForURIs(document.getDocumentElement(), uris);
    
    
        Enumeration e = uris.elements();
        while (e.hasMoreElements()) {
          String uri = (String) e.nextElement();
          visited.addElement(uri);
          listURIs(uri); 
        }
      
      }
    
    }
    catch (SAXException e) {
      // couldn't load the document, 
      // probably not well-formed XML, skip it 
    }
    catch (IOException e) {
      // couldn't load the document, 
      // likely network failure, skip it 
    }
    finally { 
      currentDepth--;
      System.out.flush();     
    }
      
  }
  
  // use recursion 
  public static void searchForURIs(Element element, Vector uris) {
    
    // look for XLinks in this element
    String uri = element.getAttributeNS("http://www.w3.org/1999/xlink", "href");

    if (uri != null && !uri.equals("") 
         && !visited.contains(uri) 
         && !uris.contains(uri)) {
      System.out.println(uri);
      uris.addElement(uri);
    }
    
    // process child elements recursively
    NodeList children = element.getChildNodes();
    for (int i = 0; i < children.getLength(); i++) {
      Node n = children.item(i);
      if (n instanceof Element) {
        searchForURIs((Element) n, uris);
      } 
    }
    
  }
  

  public static void main(String[] args) {
    
    if (args.length == 0) {
      System.out.println("Usage: java DOMSpider URL1 URL2..."); 
    } 
      
    // start parsing... 
    for (int i = 0; i < args.length; i++) {
      
      try {
        listURIs(args[i]);
      }
      catch (Exception e) {
        System.err.println(e);
        e.printStackTrace(); 
      }
      
    } // end for
  
  } // end main

} // end DOMSpider

ProcessingInstruction Nodes

The ProcessingInstruction Interface

package org.w3c.dom;

public interface ProcessingInstruction extends Node {

  public String  getTarget();
  public String  getData();
  public void    setData(String data) throws DOMException;
  
}

XLinkSpider that Respects robots processing instruction

import org.xml.sax.*;
import org.apache.xerces.parsers.*;
import java.io.*;
import java.util.*;
import org.w3c.dom.*;


public class PoliteDOMSpider {

  private static DOMParser parser = new DOMParser();
  
  // namespace suport is turned off by default in Xerces
  static {
    try {
      parser.setFeature("http://xml.org/sax/features/namespaces", 
       true); 
    }
    catch (Exception e) {
      System.err.println(e);
    }
  }
  
  private static Vector visited = new Vector();
  
  private static int maxDepth = 5;
  private static int currentDepth = 0; 
  
  public static void listURIs(String systemId) {
    
    currentDepth++;
    try {
      if (currentDepth < maxDepth) {
        parser.parse(systemId);
     
        Document document = parser.getDocument();   
    
        if (robotsAllowed(document)) {
          Vector uris = new Vector();
          // search the document for uris,
          // store them in vector, print them
          searchForURIs(document.getDocumentElement(), uris);
    
          Enumeration e = uris.elements();
          while (e.hasMoreElements()) {
            String uri = (String) e.nextElement();
            visited.addElement(uri);
            listURIs(uri); 
          }
          
        }
      
      }
    
    }
    catch (SAXException e) {
      // couldn't load the document, 
      // probably not well-formed XML, skip it 
    }
    catch (IOException e) {
      // couldn't load the document, 
      // likely network failure, skip it 
    }
    finally { 
      currentDepth--;
      System.out.flush();     
    }
      
  }
  
  public static boolean robotsAllowed(Document document) {
    
    NodeList children = document.getChildNodes();
    for (int i = 0; i < children.getLength(); i++) {
      Node n = children.item(i);
      if (n instanceof ProcessingInstruction) {
        ProcessingInstruction pi = (ProcessingInstruction) n;
        if (pi.getTarget().equals("robots")) {
          String data = pi.getData();
          if (data.indexOf("follow=\"no\"") >= 0) {
            return false; 
          } 
        }
      }
    }
    
    return true;
    
  }
  
  
  // use recursion 
  public static void searchForURIs(Element element, Vector uris) {
    
    // look for XLinks in this element
    String uri = element.getAttributeNS("http://www.w3.org/1999/xlink", "href");

    if (uri != null && !uri.equals("") 
         && !visited.contains(uri) 
         && !uris.contains(uri)) {
      System.out.println(uri);
      uris.addElement(uri);
    }
    
    // process child elements recursively
    NodeList children = element.getChildNodes();
    for (int i = 0; i < children.getLength(); i++) {
      Node n = children.item(i);
      if (n instanceof Element) {
        searchForURIs((Element) n, uris);
      } 
    }
    
  }
  

  public static void main(String[] args) {
    
    if (args.length == 0) {
      System.out.println("Usage: java PoliteDOMSpider URL1 URL2..."); 
    } 
      
    // start parsing... 
    for (int i = 0; i < args.length; i++) {
      
      try {
        listURIs(args[i]);
      }
      catch (Exception e) {
        System.err.println(e);
        e.printStackTrace(); 
      }
      
    } // end for
  
  } // end main

} // end PoliteDOMSpider

Comment Nodes

The Comment Interface

package org.w3c.dom;

public interface Comment extends CharacterData {
}

Comment Example

import org.apache.xerces.parsers.*;
import org.w3c.dom.*;
import org.xml.sax.*;
import java.io.*;


public class DOMCommentReader {

  public static void main(String[] args) {
     
    DOMParser parser = new DOMParser();
    
    for (int i = 0; i < args.length; i++) {
      try {
        // Read the entire document into memory
        parser.parse(args[i]); 
       
        Document d = parser.getDocument();
        processNode(d);
      }
      catch (SAXException e) {
        System.err.println(e); 
      }
      catch (IOException e) {
        System.err.println(e); 
      }
      
    }
  
  } // end main

  // note use of recursion
  public static void processNode(Node node) {
    
    int type = node.getNodeType();
    if (type == Node.COMMENT_NODE) {
      System.out.println(node.getNodeValue());
      System.out.println();
    }
    else {
      if (node.hasChildNodes()) {
        NodeList children = node.getChildNodes();
        for (int i = 0; i < children.getLength(); i++) {
          processNode(children.item(i));
        } 
      }
    }
    
  }

}

DOMCommentReader Output

% java DOMCommentReader hotcop.xml
 The publisher is actually Polygram but I needed
       an example of a general entity reference.

 You can tell what album I was
     listening to when I wrote this example

Or try http://www.w3.org/TR/1998/REC-xml-19980210.xml for more interesting output

Entity Nodes

The Entity Interface

package org.w3c.dom;

public interface Entity extends Node {

  public String  getPublicId();
  public String  getSystemId();
  public String  getNotationName();
  
}

DOMException

Questions?

The org.w3c.dom.traversal Package

Four interfaces:

NodeIterator

package org.w3c.dom.traversal;

public interface NodeIterator {

  public int        getWhatToShow();
  public NodeFilter getFilter();
  public boolean    getExpandEntityReferences();
  public Node       nextNode() throws DOMException;
  public Node       previousNode() throws DOMException;
  public void       detach();
    
}

ValueReporter

import org.apache.xerces.parsers.*;
import org.apache.xerces.dom.*;
import org.w3c.dom.*;
import org.w3c.dom.traversal.*;
import org.xml.sax.*;
import java.io.*;


public class ValueReporter {

  public static void main(String[] args) {
     
    DOMParser parser = new DOMParser();
    
    for (int i = 0; i < args.length; i++) {
      try {
        // Read the entire document into memory
        parser.parse(args[i]); 
       
        Document doc = parser.getDocument();
        DocumentImpl impl = (DocumentImpl) doc;
        NodeIterator iterator = impl.createNodeIterator(doc.getDocumentElement(),
         NodeFilter.SHOW_ALL, null, true);
        Node node;
        while ((node = iterator.nextNode()) != null) {
          processNode(node);      
        }
      }
      catch (SAXException e) {
        System.err.println(e); 
      }
      catch (IOException e) {
        System.err.println(e); 
      }
      
    }
  
  } // end main

  public static void processNode(Node node) {
    
    String name = node.getNodeName();
    String type = getTypeName(node.getNodeType());
    String value = node.getNodeValue();
    System.out.println("Type " + type + ": " + name 
     + " \"" + value + "\"");
    
  }
  
  public static String getTypeName(int type) {
    
    switch (type) {
      case Node.ELEMENT_NODE: return "Element";
      case Node.ATTRIBUTE_NODE: return "Attribute";
      case Node.TEXT_NODE: return "Text";
      case Node.CDATA_SECTION_NODE: return "CDATA Section";
      case Node.ENTITY_REFERENCE_NODE: return "Entity Reference";
      case Node.ENTITY_NODE: return "Entity";
      case Node.PROCESSING_INSTRUCTION_NODE: return "Processing Instruction";
      case Node.COMMENT_NODE : return "Comment";
      case Node.DOCUMENT_NODE: return "Document";
      case Node.DOCUMENT_TYPE_NODE: return "Document Type Declaration";
      case Node.DOCUMENT_FRAGMENT_NODE: return "Document Fragment";
      case Node.NOTATION_NODE: return "Notation";
      default: return "Unknown Type"; 
    }
    
  }

}

ValueReporter Output

% java ValueReporter hotcop.xml
Type Element: SONG "null"
Type Text: #text "
  "
Type Element: TITLE "null"
Type Text: #text "Hot Cop"
Type Text: #text "
  "
Type Element: PHOTO "null"
Type Text: #text "
  "
Type Element: COMPOSER "null"
Type Text: #text "Jacques Morali"
Type Text: #text "
  "
Type Element: COMPOSER "null"
Type Text: #text "Henri Belolo"
Type Text: #text "
  "
Type Element: COMPOSER "null"
Type Text: #text "Victor Willis"
Type Text: #text "
  "
Type Element: PRODUCER "null"
Type Text: #text "Jacques Morali"
Type Text: #text "
  "
Type Comment: #comment " The publisher is actually Polygram but I needed
       an example of a general entity reference. "
Type Text: #text "
  "
Type Element: PUBLISHER "null"
Type Text: #text "
    A & M Records
  "
Type Text: #text "
  "
Type Element: LENGTH "null"
Type Text: #text "6:20"
Type Text: #text "
  "
Type Element: YEAR "null"
Type Text: #text "1978"
Type Text: #text "
  "
Type Element: ARTIST "null"
Type Text: #text "Village People"
Type Text: #text "
"

Attributes are missing from this output. They are not nodes. They are properties of nodes.

NodeFilter

package org.w3c.dom.traversal;

public interface NodeFilter {

  // Constants returned by acceptNode
  public static final short FILTER_ACCEPT             = 1;
  public static final short FILTER_REJECT             = 2;
  public static final short FILTER_SKIP               = 3;

  // Constants for whatToShow
  public static final int   SHOW_ALL                  = 0x0000FFFF;
  public static final int   SHOW_ELEMENT              = 0x00000001;
  public static final int   SHOW_ATTRIBUTE            = 0x00000002;
  public static final int   SHOW_TEXT                 = 0x00000004;
  public static final int   SHOW_CDATA_SECTION        = 0x00000008;
  public static final int   SHOW_ENTITY_REFERENCE     = 0x00000010;
  public static final int   SHOW_ENTITY               = 0x00000020;
  public static final int   SHOW_PROCESSING_INSTRUCTION = 0x00000040;
  public static final int   SHOW_COMMENT              = 0x00000080;
  public static final int   SHOW_DOCUMENT             = 0x00000100;
  public static final int   SHOW_DOCUMENT_TYPE        = 0x00000200;
  public static final int   SHOW_DOCUMENT_FRAGMENT    = 0x00000400;
  public static final int   SHOW_NOTATION             = 0x00000800;

  public short        acceptNode(Node n);
    
}

DOM based TagStripper

import org.apache.xerces.parsers.*;
import org.apache.xerces.dom.*;
import org.w3c.dom.*;
import org.w3c.dom.traversal.*;
import org.xml.sax.SAXException;
import java.io.IOException;


public class DOMTagStripper {

  public static void main(String[] args) {
     
    DOMParser parser = new DOMParser();
    
    for (int i = 0; i < args.length; i++) {
      try {
        // Read the entire document into memory
        parser.parse(args[i]); 
       
        Document doc = parser.getDocument();
        DocumentImpl impl = (DocumentImpl) doc;
        NodeIterator iterator = impl.createNodeIterator(doc.getDocumentElement(),
         NodeFilter.SHOW_TEXT, null, true);
        Node node;
        while ((node = iterator.nextNode()) != null) {
          System.out.print(node.getNodeValue());      
        }
      }
      catch (SAXException e) {
        System.err.println(e); 
      }
      catch (IOException e) {
        System.err.println(e); 
      }
      
    }
  
  } // end main

}

Output from a DOM based TagStripper

% java DOMTagStripper hotcop.xml

  Hot Cop
  Jacques Morali
  Henri Belolo
  Victor Willis
  Jacques Morali

  A & M Records
  6:20
  1978
  Village People

Questions?

Writing XML Documents with DOM

org.apache.xerces.dom.DOMImplementationImpl

package org.apache.xerces.dom;

public class DOMImplementationImpl implements DOMImplementation {

  public boolean hasFeature(String feature, String version) 
  
  public static DOMImplementation getDOMImplementation()
  
  public DocumentType createDocumentType(String qualifiedName, 
   String publicID, String systemID, String internalSubset)
                                          
  public Document createDocument(String namespaceURI, 
   String qualifiedName, DocumentType doctype)
   throws DOMException

}

A DOM program that writes Fibonacci numbers into an XML document

import java.math.*;
import java.io.*;
import org.w3c.dom.*;
import org.apache.xerces.dom.*;
import org.apache.xml.serialize.*;


public class FibonacciDOM {

  public static void main(String[] args) {

    try {

      DOMImplementation impl 
       = DOMImplementationImpl.getDOMImplementation();

      Document fibonacci 
       = impl.createDocument(null, "Fibonacci_Numbers", null);

      BigInteger low  = BigInteger.ZERO;
      BigInteger high = BigInteger.ONE;

      Element root = fibonacci.getDocumentElement();

      for (int i = 0; i <= 25; i++) {
        Element number = fibonacci.createElement("fibonacci");
        number.setAttribute("index", Integer.toString(i));
        Text text = fibonacci.createTextNode(low.toString());
        number.appendChild(text);
        root.appendChild(number);

        BigInteger temp = high;
        high = high.add(low);
        low = temp;
      }

      // Now the document has been created and exists in memory
    }
    catch (DOMException e) {
      e.printStackTrace();
    }

  }

}

Serialization

A DOM program that writes Fibonacci numbers onto System.out

import java.math.*;
import java.io.*;
import org.w3c.dom.*;
import org.apache.xerces.dom.*;
import org.apache.xml.serialize.*; 


public class FibonacciDOMSerializer {

  public static void main(String[] args) {
   
    try {
      
      DOMImplementation impl 
       = DOMImplementationImpl.getDOMImplementation();

      Document fibonacci 
       = impl.createDocument(null, "Fibonacci_Numbers", null);
      
      BigInteger low  = BigInteger.ZERO;
      BigInteger high = BigInteger.ONE;      
      
      Element root = fibonacci.getDocumentElement(); 

      for (int i = 0; i <= 25; i++) {
        Element number = fibonacci.createElement("fibonacci");
        number.setAttribute("index", Integer.toString(i));
        Text text = fibonacci.createTextNode(low.toString());
        number.appendChild(text);
        root.appendChild(number);
        
        BigInteger temp = high;
        high = high.add(low);
        low = temp;
      }
      
      try {
        // Now that the document is created we need to *serialize* it
        OutputFormat format = new OutputFormat(fibonacci);
        XMLSerializer serializer 
         = new XMLSerializer(System.out, format);
        serializer.serialize(fibonacci);
      }
      catch (IOException e) {
        System.err.println(e); 
      }
    }
    catch (DOMException e) {
      e.printStackTrace();
    }

  }

}

fibonacci.xml

<?xml version="1.0" encoding="UTF-8"?>
<Fibonacci_Numbers><fibonacci index="0">0</fibonacci><fibonacci index="1">1</fibonacci><fibonacci index="2">1</fibonacci><fibonacci index="3">2</fibonacci><fibonacci index="4">3</fibonacci><fibonacci index="5">5</fibonacci><fibonacci index="6">8</fibonacci><fibonacci index="7">13</fibonacci><fibonacci index="8">21</fibonacci><fibonacci index="9">34</fibonacci><fibonacci index="10">55</fibonacci><fibonacci index="11">89</fibonacci><fibonacci index="12">144</fibonacci><fibonacci index="13">233</fibonacci><fibonacci index="14">377</fibonacci><fibonacci index="15">610</fibonacci><fibonacci index="16">987</fibonacci><fibonacci index="17">1597</fibonacci><fibonacci index="18">2584</fibonacci><fibonacci index="19">4181</fibonacci><fibonacci index="20">6765</fibonacci><fibonacci index="21">10946</fibonacci><fibonacci index="22">17711</fibonacci><fibonacci index="23">28657</fibonacci><fibonacci index="24">46368</fibonacci><fibonacci index="25">75025</fibonacci></Fibonacci_Numbers>

OutputFormat

package org.apache.xml.serialize;

public class OutputFormat extends Object {

  public OutputFormat()
  public OutputFormat(String method, String encoding, boolean indenting)
  public OutputFormat(Document doc)
  public OutputFormat(Document doc, String encoding, boolean indenting)
  
  public String   getMethod()
  public void     setMethod(String method)
  public String   getVersion()
  public void     setVersion(String version)
  public int      getIndent()
  public boolean  getIndenting()
  public void     setIndent(int indent)
  public void     setIndenting(boolean on)
  public String   getEncoding()
  public void     setEncoding(String encoding)
  public String   getMediaType()
  public void     setMediaType(String mediaType)
  public void     setDoctype(String publicID, String systemID)
  public String   getDoctypePublic()
  public String   getDoctypeSystem()
  public boolean  getOmitXMLDeclaration()
  public void     setOmitXMLDeclaration(boolean omit)
  public boolean  getStandalone()
  public void     setStandalone(boolean standalone)
  public String[] getCDataElements()
  public boolean  isCDataElement(String tagName)
  public void     setCDataElements(String[] cdataElements)
  public String[] getNonEscapingElements()
  public boolean  isNonEscapingElement(String tagName)
  public void     setNonEscapingElements(String[] nonEscapingElements)
  public String   getLineSeparator()
  public void     setLineSeparator(String lineSeparator)
  public boolean  getPreserveSpace()
  public void     setPreserveSpace(boolean preserve)
  public int      getLineWidth()
  public void     setLineWidth(int lineWidth)
  public char     getLastPrintable()
  
  public static String whichMethod(Document doc)
  public static String whichDoctypePublic(Document doc)
  public static String whichDoctypeSystem(Document doc)
  public static String whichMediaType(String method)
  
}

Better formatted output

 try {
  // Now that the document is created we need to *serialize* it
  OutputFormat format = new OutputFormat(fibonacci, "8859_1", true);
  format.setLineSeparator("\r\n");
  format.setLineWidth(72);
  format.setDoctype(null, "fibonacci.dtd");
  XMLSerializer serializer = new XMLSerializer(System.out, format);
  serializer.serialize(root);
}
catch (IOException e) {
  System.err.println(e); 
}

formatted_fibonacci.xml

<?xml version="1.0" encoding="8859_1"?>
<!DOCTYPE Fibonacci_Numbers SYSTEM "fibonacci.dtd">
<Fibonacci_Numbers>
    <fibonacci index="0">0</fibonacci>
    <fibonacci index="1">1</fibonacci>
    <fibonacci index="2">1</fibonacci>
    <fibonacci index="3">2</fibonacci>
    <fibonacci index="4">3</fibonacci>
    <fibonacci index="5">5</fibonacci>
    <fibonacci index="6">8</fibonacci>
    <fibonacci index="7">13</fibonacci>
    <fibonacci index="8">21</fibonacci>
    <fibonacci index="9">34</fibonacci>
    <fibonacci index="10">55</fibonacci>
    <fibonacci index="11">89</fibonacci>
    <fibonacci index="12">144</fibonacci>
    <fibonacci index="13">233</fibonacci>
    <fibonacci index="14">377</fibonacci>
    <fibonacci index="15">610</fibonacci>
    <fibonacci index="16">987</fibonacci>
    <fibonacci index="17">1597</fibonacci>
    <fibonacci index="18">2584</fibonacci>
    <fibonacci index="19">4181</fibonacci>
    <fibonacci index="20">6765</fibonacci>
    <fibonacci index="21">10946</fibonacci>
    <fibonacci index="22">17711</fibonacci>
    <fibonacci index="23">28657</fibonacci>
    <fibonacci index="24">46368</fibonacci>
    <fibonacci index="25">75025</fibonacci>
</Fibonacci_Numbers>

DOM based XMLPrettyPrinter

import org.apache.xerces.parsers.*;
import org.w3c.dom.*;
import org.xml.sax.*;
import java.io.*;
import org.apache.xerces.dom.*;
import org.apache.xml.serialize.*; 


public class DOMPrettyPrinter {

  public static void main(String[] args) { 
     
    DOMParser parser = new DOMParser();
    
    for (int i = 0; i < args.length; i++) {
      try {
        // Read the entire document into memory
        parser.parse(args[i]); 
       
        Document document = parser.getDocument();
        
        OutputFormat format 
         = new OutputFormat(document, "UTF-8", true);
        format.setLineSeparator("\r\n");
        format.setIndent(2);
        format.setLineWidth(72);
        format.setPreserveSpace(false);
        XMLSerializer serializer 
         = new XMLSerializer(System.out, format);
        serializer.serialize(document);     
      }
      catch (SAXException e) {
        System.err.println(e); 
      }
      catch (IOException e) {
        System.err.println(e); 
      }
      
    }
  
  } // end main

}

Output from a DOM based XMLPrettyPrinter

The point is this:

To Learn More


Questions?

Part V: JDOM

There is no compelling reason for a Java API to manipulate XML to be complex, tricky, unintuitive, or a pain in the neck.
--JDOM Mission Statement

Where we're going

What is JDOM?

About JDOM

JDOM versions

Four packages:

org.jdom
the classes that represent an XML document and its parts
org.jdom.input
classes for reading a document into memory
org.jdom.output
classes for writing a document onto a stream or other target (e.g. SAX or DOM app)
org.jdom.adapters
classes for hooking up to DOM implementations

The org.jdom package

The classes that represent an XML document and its parts

The org.jdom.input package

Classes for reading a document into memory from a file or other source

The org.jdom.output package

The classes for writing a document to a file or other target

The org.jdom.adapters package

Writing XML Documents with JDOM

A JDOM program that writes this XML document

<?xml version="1.0"?>
<GREETING>
  Hello JDOM!
</GREETING>

Hello JDOM

import org.jdom.*;
import org.jdom.output.XMLOutputter;


public class HelloJDOM {

  public static void main(String[] args) {
   
    Element root = new Element("GREETING");
    	
    root.setText("Hello JDOM!");
         
    Document doc = new Document(root);      
    
    // At this point the document only exists in memory.
    // We still need to serialize it
    XMLOutputter outputter = new XMLOutputter();
    try {
      outputter.output(doc, System.out);       
    }
    catch (Exception e) {
      System.err.println(e);
    }

  }

}

Actual Output

<?xml version="1.0" encoding="UTF-8"?><GREETING>Hello JDOM!</GREETING>

This is more or less what we wanted, modulo white space.

Hello DOM

Here's the same program using DOM instead of JDOM. Which is simpler?

import java.io.*;
import org.w3c.dom.*;
import org.apache.xerces.dom.*;
import org.apache.xml.serialize.*;


public class HelloDOM {

  public static void main(String[] args) {

    try {

      DOMImplementation impl = DOMImplementationImpl.getDOMImplementation();
      //                       ^^^^^^^^^^^^^^^^^^^^^
      //                       Xerces Specific class

      Document hello = impl.createDocument(null, "GREETING", null);
      //                                   ^^^^              ^^^^
      //                               Namespace URI       DocType

      Element root = hello.getDocumentElement();

      // We can't use a raw string. Instead we have to first create
      // a text node.
      Text text = hello.createTextNode("Hello DOM!");
      root.appendChild(text);

      // Now that the document is created we need to *serialize* it
      try {
        OutputFormat format = new OutputFormat(hello);
        XMLSerializer serializer 
         = new XMLSerializer(System.out, format);
        serializer.serialize(root);
      }
      catch (IOException e) {
        System.err.println(e);
      }
    }
    catch (DOMException e) {
      e.printStackTrace();
    }

  }

}

fibonacci.xml

Suppose we want data in an XML document that looks something like this:

<?xml version="1.0" encoding="UTF-8"?>
<Fibonacci_Numbers>
  <fibonacci index="0">0</fibonacci>
  <fibonacci index="1">1</fibonacci>
  <fibonacci index="2">1</fibonacci>
  <fibonacci index="3">2</fibonacci>
  <fibonacci index="4">3</fibonacci>
  <fibonacci index="5">5</fibonacci>
  <fibonacci index="6">8</fibonacci>
  <fibonacci index="7">13</fibonacci>
  <fibonacci index="8">21</fibonacci>
  <fibonacci index="9">34</fibonacci>
  <fibonacci index="10">55</fibonacci>
  <fibonacci index="11">89</fibonacci>
  <fibonacci index="12">144</fibonacci>
  <fibonacci index="13">233</fibonacci>
  <fibonacci index="14">377</fibonacci>
  <fibonacci index="15">610</fibonacci>
  <fibonacci index="16">987</fibonacci>
  <fibonacci index="17">1597</fibonacci>
  <fibonacci index="18">2584</fibonacci>
  <fibonacci index="19">4181</fibonacci>
  <fibonacci index="20">6765</fibonacci>
  <fibonacci index="21">10946</fibonacci>
  <fibonacci index="22">17711</fibonacci>
  <fibonacci index="23">28657</fibonacci>
  <fibonacci index="24">46368</fibonacci>
  <fibonacci index="25">75025</fibonacci>
</Fibonacci_Numbers>

A JDOM program that writes Fibonacci numbers into an XML file

import org.jdom.Element;
import org.jdom.Document;
import org.jdom.output.XMLOutputter;
import java.math.BigInteger;
import java.io.*;


public class FibonacciJDOM {

  public static void main(String[] args) {

    Element root = new Element("Fibonacci_Numbers");

    BigInteger low  = BigInteger.ZERO;
    BigInteger high = BigInteger.ONE;

    for (int i = 0; i <= 25; i++) {
      Element fibonacci = new Element("fibonacci");
      fibonacci.addAttribute("index", String.valueOf(i));
      fibonacci.setText(low.toString());
      root.addContent(fibonacci);

      BigInteger temp = high;
      high = high.add(low);
      low = temp;
    }

    Document doc = new Document(root);
    // serialize it into a file
    try {
      FileOutputStream out 
       = new FileOutputStream("fibonacci_jdom.xml");
      XMLOutputter serializer = new XMLOutputter();
      serializer.output(doc, out);
      out.flush();
      out.close();
    }
    catch (IOException e) {
      System.err.println(e);
    }

  }

}

Output

Again, modulo white space this is correct

<?xml version="1.0" encoding="UTF-8"?><Fibonacci_Numbers><fibonacci index="0">0</fibonacci><fibonacci index="1">1</fibonacci><fibonacci index="2">1</fibonacci><fibonacci index="3">2</fibonacci><fibonacci index="4">3</fibonacci><fibonacci index="5">5</fibonacci><fibonacci index="6">8</fibonacci><fibonacci index="7">13</fibonacci><fibonacci index="8">21</fibonacci><fibonacci index="9">34</fibonacci><fibonacci index="10">55</fibonacci><fibonacci index="11">89</fibonacci><fibonacci index="12">144</fibonacci><fibonacci index="13">233</fibonacci><fibonacci index="14">377</fibonacci><fibonacci index="15">610</fibonacci><fibonacci index="16">987</fibonacci><fibonacci index="17">1597</fibonacci><fibonacci index="18">2584</fibonacci><fibonacci index="19">4181</fibonacci><fibonacci index="20">6765</fibonacci><fibonacci index="21">10946</fibonacci><fibonacci index="22">17711</fibonacci><fibonacci index="23">28657</fibonacci><fibonacci index="24">46368</fibonacci><fibonacci index="25">75025</fibonacci></Fibonacci_Numbers>

Suppose you want to include a DTD

ValidFibonacci

import java.math.*;
import java.io.*;
import org.jdom.*;
import org.jdom.output.XMLOutputter;


public class ValidFibonacci {

  public static void main(String[] args) {
   
    Element root = new Element("Fibonacci_Numbers");	
  	      
    BigInteger low  = BigInteger.ZERO;
    BigInteger high = BigInteger.ONE;      
    
    for (int i = 0; i <= 25; i++) {
      Element fibonacci = new Element("fibonacci");
      Attribute index = new Attribute("index", String.valueOf(i));
      fibonacci.addAttribute(index);
      fibonacci.setText(low.toString());
      BigInteger temp = high;
      high = high.add(low);
      low = temp;
      root.addContent(fibonacci);
    }
 
    DocType type = new DocType("Fibonacci_Numbers", "fibonacci.dtd");
 
    Document doc = new Document(root, type);
    // serialize it into a file
    try {
      FileOutputStream out = new FileOutputStream("validfibonacci.xml");
      XMLOutputter serializer = new XMLOutputter(); 
      serializer.output(doc, out);
      out.flush();	
      out.close();
    }
    catch (IOException e) {
      System.err.println(e);
    }

  }

}
View Output in Browser

validfibonacci.xml

<?xml version="1.0" encoding="UTF-8"?><!DOCTYPE Fibonacci_Numbers SYSTEM "fibonacci.dtd"><Fibonacci_Numbers><fibonacci index="0">0</fibonacci><fibonacci index="1">1</fibonacci><fibonacci index="2">1</fibonacci><fibonacci index="3">2</fibonacci><fibonacci index="4">3</fibonacci><fibonacci index="5">5</fibonacci><fibonacci index="6">8</fibonacci><fibonacci index="7">13</fibonacci><fibonacci index="8">21</fibonacci><fibonacci index="9">34</fibonacci><fibonacci index="10">55</fibonacci><fibonacci index="11">89</fibonacci><fibonacci index="12">144</fibonacci><fibonacci index="13">233</fibonacci><fibonacci index="14">377</fibonacci><fibonacci index="15">610</fibonacci><fibonacci index="16">987</fibonacci><fibonacci index="17">1597</fibonacci><fibonacci index="18">2584</fibonacci><fibonacci index="19">4181</fibonacci><fibonacci index="20">6765</fibonacci><fibonacci index="21">10946</fibonacci><fibonacci index="22">17711</fibonacci><fibonacci index="23">28657</fibonacci><fibonacci index="24">46368</fibonacci><fibonacci index="25">75025</fibonacci></Fibonacci_Numbers>

Using Namespaces

Rules for Using Namespaces

With Namespace Prefixes

import org.jdom.Element;
import org.jdom.Document;
import org.jdom.output.XMLOutputter;
import java.math.BigInteger;
import java.io.*;


public class PrefixedFibonacci {

  public static void main(String[] args) {

    Element root = new Element("math", "mathml",
     "http://www.w3.org/1998/Math/MathML");

    BigInteger low  = BigInteger.ZERO;
    BigInteger high = BigInteger.ONE;

    for (int i = 0; i <= 25; i++) {

      Element mrow = new Element("mrow", "mathml",
       "http://www.w3.org/1998/Math/MathML");

      Element mi = new Element("mi", "mathml",
       "http://www.w3.org/1998/Math/MathML");
      mi.setText("f(" + i + ")");
      mrow.addContent(mi);

      Element mo = new Element("mo", "mathml",
       "http://www.w3.org/1998/Math/MathML");
      mo.setText("=");
      mrow.addContent(mo);

      Element mn = new Element("mn", "mathml",
       "http://www.w3.org/1998/Math/MathML");
      mn.setText(low.toString());
      mrow.addContent(mn);

      BigInteger temp = high;
      high = high.add(low);
      low = temp;
      root.addContent(mrow);

    }

    Document doc = new Document(root);
    // serialize it into a file
    try {
      FileOutputStream out 
       = new FileOutputStream("prefixed_fibonacci.xml");
      XMLOutputter serializer = new XMLOutputter();
      serializer.output(doc, out);
      out.flush();
      out.close();
    }
    catch (IOException e) {
      System.err.println(e);
    }

  }

}
View Output in Browser

The Default, Unprefixed Namespace

Rules for Using Default Namespace

With Default Namespace

import org.jdom.Element;
import org.jdom.Document;
import org.jdom.output.XMLOutputter;
import java.math.BigInteger;
import java.io.*;


public class UnprefixedFibonacci {

  public static void main(String[] args) {
   
    Element root = new Element("math", "http://www.w3.org/1998/Math/MathML");	
  	      
    BigInteger low  = BigInteger.ZERO;
    BigInteger high = BigInteger.ONE;      
    
    for (int i = 0; i <= 25; i++) {
        
      Element mrow = new Element("mrow", "http://www.w3.org/1998/Math/MathML");
      
      Element mi = new Element("mi", "http://www.w3.org/1998/Math/MathML");
      mi.setText("f(" + i + ")"); 
      mrow.addContent(mi);
      
      Element mo = new Element("mo", "http://www.w3.org/1998/Math/MathML");
      mo.setText("="); 
      mrow.addContent(mo);
      
      Element mn = new Element("mn", "http://www.w3.org/1998/Math/MathML");
      mn.setText(low.toString());
      mrow.addContent(mn);

      BigInteger temp = high;
      high = high.add(low);
      low = temp;
      root.addContent(mrow);
      
    }
 
    Document doc = new Document(root);
    // serialize it into a file
    try {
      FileOutputStream out = new FileOutputStream("unprefixed_fibonacci.xml");
      XMLOutputter serializer = new XMLOutputter(); 
      serializer.output(doc, out);
      out.flush();	
      out.close();
    }
    catch (IOException e) {
      System.err.println(e);
    }

  }

}
View Output in Browser

Converting data to XML

Sample Tab Delimited Data: Baseball Statistics

SurnameFirstNameTeamPositionGames PlayedGames StartedAtBatsRunsHitsDoublesTriplesHome runsRBIStolen BasesCaught StealingSacrifice HitsSacrifice FliesErrorsPBWalksStrike outsHit by pitch
AndersonGarret ANAOutfield15615162262183417157983336029801
BaughmanJustin ANASecond Base625419624509112010453806361
BolickFrank ANAThird Base2111453720120000001180
DisarcinaGary ANAShortstop1571555517315839335612712314021518
EdmondsJim ANAOutfield1541505991151844212591751150571141
ErstadDarin ANAOutfield133129537841593931982206133043776
GarciaCarlos ANASecond Base1910354510002010103111
GlausTroy ANAThird Base484516519369012310027015510
GreeneTodd ANAOutfield29157131840170000002200
HelfandEric ANACatcher000000000000000000
HollinsDave ANAThird Base10198363608816211391132217044697
JefferiesGregg ANAOutfield19187272560110100000050
JohnsonMark ANAFirst Base10214110000000000060
KreuterChad ANACatcher9674252276310123310519533493
MartinNorberto ANASecond Base79501952042201133132406290
MashoreDamon ANAOutfield4324981323602111010009223
MolinaBen ANACatcher201000000000000000
NevinPhil ANACatcher7565237275481827000252017675
O'BrienCharlie ANACatcher625817513459041800334110332
PalmeiroOrlando ANAOutfield743416528537202154700020110
PritchettChris ANAFirst Base311980122321282000104160
SalmonTim ANADesignated Hitter1361304638413928126880101020901003
ShipleyCraig ANAThird Base77321471838712170441305225
VelardeRandy ANASecond Base5150188294913142672014034421
WalbeckMatt ANACatcher10891338418715264611557830682
WilliamsReggie ANAOutfield2973671310153310007111

A Program to convert tab delimited data to XML

import java.io.*;
import org.jdom.*;
import org.jdom.output.XMLOutputter;


public class BaseballTabToXML {

  public static void main(String[] args) {
     
    Element root = new Element("players");
    
    try {
      FileInputStream fin = new FileInputStream(args[0]);
      BufferedReader in 
       = new BufferedReader(new InputStreamReader(fin));    

      String playerStats;  
      while ((playerStats = in.readLine()) != null) {
        String[] stats = splitLine(playerStats);
        
        Element player = new Element("player");

        Element first_name = new Element("first_name");
        first_name.setText(stats[1]);
        player.addContent(first_name);
        
        Element surname = new Element("surname");
        surname.setText(stats[0]);
        player.addContent(surname);
       
        Element games_played = new Element("games_played");
        games_played.setText(stats[4]);
        player.addContent(games_played);
       
        Element at_bats = new Element("at_bats");
        at_bats.setText(stats[6]);
        player.addContent(at_bats);
       
        Element runs = new Element("runs");
        runs.setText(stats[7]);
        player.addContent(runs);
       
        Element hits = new Element("hits");
        hits.setText(stats[8]);
        player.addContent(hits);
       
        Element doubles = new Element("doubles");
        doubles.setText(stats[9]);
        player.addContent(doubles);
       
        Element triples = new Element("triples");
        triples.setText(stats[10]);
        player.addContent(triples); 

        Element home_runs = new Element("home_runs");
        home_runs.setText(stats[11]);
        player.addContent(home_runs); 

        Element runs_batted_in = new Element("runs_batted_in");
        runs_batted_in.setText(stats[12]);
        player.addContent(runs_batted_in); 

        Element stolen_bases = new Element("stolen_bases");
        stolen_bases.setText(stats[13]);
        player.addContent(stolen_bases); 

        Element caught_stealing = new Element("caught_stealing");
        caught_stealing.setText(stats[14]);
        player.addContent(caught_stealing); 

        Element sacrifice_hits = new Element("sacrifice_hits");
        sacrifice_hits.setText(stats[15]);
        player.addContent(sacrifice_hits); 

        Element sacrifice_flies = new Element("sacrifice_flies");
        sacrifice_flies.setText(stats[16]);
        player.addContent(sacrifice_flies); 

        Element errors = new Element("errors");
        errors.setText(stats[17]);
        player.addContent(errors); 

        Element passed_by_ball = new Element("passed_by_ball");
        passed_by_ball.setText(stats[18]);
        player.addContent(passed_by_ball); 

        Element walks = new Element("walks");
        walks.setText(stats[19]);
        player.addContent(walks); 

        Element strike_outs = new Element("strike_outs");
        strike_outs.setText(stats[20]);
        player.addContent(strike_outs); 

        Element hit_by_pitch = new Element("hit_by_pitch");
        hit_by_pitch.setText(stats[21]);
        player.addContent(hit_by_pitch); 
        
        root.addContent(player);
      }  
      
      Document doc = new Document(root);
      // serialize it into a file
      FileOutputStream fout 
       = new FileOutputStream("baseballstats.xml");
      
      XMLOutputter serializer = new XMLOutputter(); 
      serializer.output(doc, fout);
      fout.flush();	
      fout.close();
      in.close();
      
    }
    catch (IOException e) {
      System.err.println(e);
    }
    catch (ArrayIndexOutOfBoundsException e) {
      System.out.println("Usage: java BaseballTabToXML input_file.tab");
    }

  }

  public static String[] splitLine(String playerStats) {
    
    // count the number of tabs
    int numTabs = 0;
    for (int i = 0; i < playerStats.length(); i++) {
      if (playerStats.charAt(i) == '\t') numTabs++;
    }
    int numFields = numTabs + 1;
    String[] fields = new String[numFields];
    int position = 0;
    for (int i = 0; i < numFields; i++) {
      StringBuffer field = new StringBuffer();
      while (position < playerStats.length() 
       && playerStats.charAt(position++) != '\t') {
        field.append(playerStats.charAt(position-1));
      }
      fields[i] = field.toString();
    }    
    return fields;
    
  }

}
View Output in Browser

Baseball Stats in XML

<?xml version="1.0"?>
<players>
  <player>
    <first_name>FirstName</first_name>
    <surname>Surname</surname>
    <games_played>Games Played</games_played>
    <at_bats>AtBats</at_bats>
    <runs>Runs</runs>
    <hits>Hits</hits>
    <doubles>Doubles</doubles>
    <triples>Triples</triples>
    <home_runs>Home runs</home_runs>
    <stolen_bases>RBI</stolen_bases>
    <caught_stealing>Caught Stealing</caught_stealing>
    <sacrifice_hits>Sacrifice Hits</sacrifice_hits>
    <sacrifice_flies>Sacrifice Flies</sacrifice_flies>
    <errors>Errors</errors>
    <passed_by_ball>PB</passed_by_ball>
    <walks>Walks</walks>
    <strike_outs>Strike outs</strike_outs>
    <hit_by_pitch>Hit by pitch</hit_by_pitch>
  </player>
  <player>
    <first_name>Garret </first_name>
    <surname>Anderson</surname>
    <games_played>156</games_played>
    <at_bats>622</at_bats>
    <runs>62</runs>
    <hits>183</hits>
    <doubles>41</doubles>
    <triples>7</triples>
    <home_runs>15</home_runs>
    <stolen_bases>79</stolen_bases>
    <caught_stealing>3</caught_stealing>
    <sacrifice_hits>3</sacrifice_hits>
    <sacrifice_flies>3</sacrifice_flies>
    <errors>6</errors>
    <passed_by_ball>0</passed_by_ball>
    <walks>29</walks>
    <strike_outs>80</strike_outs>
    <hit_by_pitch>1</hit_by_pitch>
  </player>
  <player>
    <first_name>Justin </first_name>
    <surname>Baughman</surname>
    <games_played>62</games_played>
    <at_bats>196</at_bats>
    <runs>24</runs>
    <hits>50</hits>
    <doubles>9</doubles>
    <triples>1</triples>
    <home_runs>1</home_runs>
    <stolen_bases>20</stolen_bases>
    <caught_stealing>4</caught_stealing>
    <sacrifice_hits>5</sacrifice_hits>
    <sacrifice_flies>3</sacrifice_flies>
    <errors>8</errors>
    <passed_by_ball>0</passed_by_ball>
    <walks>6</walks>
    <strike_outs>36</strike_outs>
    <hit_by_pitch>1</hit_by_pitch>
  </player>
  <player>
    <first_name>Frank </first_name>
    <surname>Bolick</surname>
    <games_played>21</games_played>
    <at_bats>45</at_bats>
    <runs>3</runs>
    <hits>7</hits>
    <doubles>2</doubles>
    <triples>0</triples>
    <home_runs>1</home_runs>
    <stolen_bases>2</stolen_bases>
    <caught_stealing>0</caught_stealing>
    <sacrifice_hits>0</sacrifice_hits>
    <sacrifice_flies>0</sacrifice_flies>
    <errors>0</errors>
    <passed_by_ball>0</passed_by_ball>
    <walks>11</walks>
    <strike_outs>8</strike_outs>
    <hit_by_pitch>0</hit_by_pitch>
  </player>
  <player>
    <first_name>Gary </first_name>
    <surname>Disarcina</surname>
    <games_played>157</games_played>
    <at_bats>551</at_bats>
    <runs>73</runs>
    <hits>158</hits>
    <doubles>39</doubles>
    <triples>3</triples>
    <home_runs>3</home_runs>
    <stolen_bases>56</stolen_bases>
    <caught_stealing>7</caught_stealing>
    <sacrifice_hits>12</sacrifice_hits>
    <sacrifice_flies>3</sacrifice_flies>
    <errors>14</errors>
    <passed_by_ball>0</passed_by_ball>
    <walks>21</walks>
    <strike_outs>51</strike_outs>
    <hit_by_pitch>8</hit_by_pitch>
  </player>
  <player>
    <first_name>Jim </first_name>
    <surname>Edmonds</surname>
    <games_played>154</games_played>
    <at_bats>599</at_bats>
    <runs>115</runs>
    <hits>184</hits>
    <doubles>42</doubles>
    <triples>1</triples>
    <home_runs>25</home_runs>
    <stolen_bases>91</stolen_bases>
    <caught_stealing>5</caught_stealing>
    <sacrifice_hits>1</sacrifice_hits>
    <sacrifice_flies>1</sacrifice_flies>
    <errors>5</errors>
    <passed_by_ball>0</passed_by_ball>
    <walks>57</walks>
    <strike_outs>114</strike_outs>
    <hit_by_pitch>1</hit_by_pitch>
  </player>
  <player>
    <first_name>Darin </first_name>
    <surname>Erstad</surname>
    <games_played>133</games_played>
    <at_bats>537</at_bats>
    <runs>84</runs>
    <hits>159</hits>
    <doubles>39</doubles>
    <triples>3</triples>
    <home_runs>19</home_runs>
    <stolen_bases>82</stolen_bases>
    <caught_stealing>6</caught_stealing>
    <sacrifice_hits>1</sacrifice_hits>
    <sacrifice_flies>3</sacrifice_flies>
    <errors>3</errors>
    <passed_by_ball>0</passed_by_ball>
    <walks>43</walks>
    <strike_outs>77</strike_outs>
    <hit_by_pitch>6</hit_by_pitch>
  </player>
  <player>
    <first_name>Carlos </first_name>
    <surname>Garcia</surname>
    <games_played>19</games_played>
    <at_bats>35</at_bats>
    <runs>4</runs>
    <hits>5</hits>
    <doubles>1</doubles>
    <triples>0</triples>
    <home_runs>0</home_runs>
    <stolen_bases>0</stolen_bases>
    <caught_stealing>0</caught_stealing>
    <sacrifice_hits>1</sacrifice_hits>
    <sacrifice_flies>0</sacrifice_flies>
    <errors>1</errors>
    <passed_by_ball>0</passed_by_ball>
    <walks>3</walks>
    <strike_outs>11</strike_outs>
    <hit_by_pitch>1</hit_by_pitch>
  </player>
  <player>
    <first_name>Troy </first_name>
    <surname>Glaus</surname>
    <games_played>48</games_played>
    <at_bats>165</at_bats>
    <runs>19</runs>
    <hits>36</hits>
    <doubles>9</doubles>
    <triples>0</triples>
    <home_runs>1</home_runs>
    <stolen_bases>23</stolen_bases>
    <caught_stealing>0</caught_stealing>
    <sacrifice_hits>0</sacrifice_hits>
    <sacrifice_flies>2</sacrifice_flies>
    <errors>7</errors>
    <passed_by_ball>0</passed_by_ball>
    <walks>15</walks>
    <strike_outs>51</strike_outs>
    <hit_by_pitch>0</hit_by_pitch>
  </player>
  <player>
    <first_name>Todd </first_name>
    <surname>Greene</surname>
    <games_played>29</games_played>
    <at_bats>71</at_bats>
    <runs>3</runs>
    <hits>18</hits>
    <doubles>4</doubles>
    <triples>0</triples>
    <home_runs>1</home_runs>
    <stolen_bases>7</stolen_bases>
    <caught_stealing>0</caught_stealing>
    <sacrifice_hits>0</sacrifice_hits>
    <sacrifice_flies>0</sacrifice_flies>
    <errors>0</errors>
    <passed_by_ball>0</passed_by_ball>
    <walks>2</walks>
    <strike_outs>20</strike_outs>
    <hit_by_pitch>0</hit_by_pitch>
  </player>
  <player>
    <first_name>Eric </first_name>
    <surname>Helfand</surname>
    <games_played>0</games_played>
    <at_bats>0</at_bats>
    <runs>0</runs>
    <hits>0</hits>
    <doubles>0</doubles>
    <triples>0</triples>
    <home_runs>0</home_runs>
    <stolen_bases>0</stolen_bases>
    <caught_stealing>0</caught_stealing>
    <sacrifice_hits>0</sacrifice_hits>
    <sacrifice_flies>0</sacrifice_flies>
    <errors>0</errors>
    <passed_by_ball>0</passed_by_ball>
    <walks>0</walks>
    <strike_outs>0</strike_outs>
    <hit_by_pitch>0</hit_by_pitch>
  </player>
  <player>
    <first_name>Dave </first_name>
    <surname>Hollins</surname>
    <games_played>101</games_played>
    <at_bats>363</at_bats>
    <runs>60</runs>
    <hits>88</hits>
    <doubles>16</doubles>
    <triples>2</triples>
    <home_runs>11</home_runs>
    <stolen_bases>39</stolen_bases>
    <caught_stealing>3</caught_stealing>
    <sacrifice_hits>2</sacrifice_hits>
    <sacrifice_flies>2</sacrifice_flies>
    <errors>17</errors>
    <passed_by_ball>0</passed_by_ball>
    <walks>44</walks>
    <strike_outs>69</strike_outs>
    <hit_by_pitch>7</hit_by_pitch>
  </player>
  <player>
    <first_name>Gregg </first_name>
    <surname>Jefferies</surname>
    <games_played>19</games_played>
    <at_bats>72</at_bats>
    <runs>7</runs>
    <hits>25</hits>
    <doubles>6</doubles>
    <triples>0</triples>
    <home_runs>1</home_runs>
    <stolen_bases>10</stolen_bases>
    <caught_stealing>0</caught_stealing>
    <sacrifice_hits>0</sacrifice_hits>
    <sacrifice_flies>0</sacrifice_flies>
    <errors>0</errors>
    <passed_by_ball>0</passed_by_ball>
    <walks>0</walks>
    <strike_outs>5</strike_outs>
    <hit_by_pitch>0</hit_by_pitch>
  </player>
  <player>
    <first_name>Mark </first_name>
    <surname>Johnson</surname>
    <games_played>10</games_played>
    <at_bats>14</at_bats>
    <runs>1</runs>
    <hits>1</hits>
    <doubles>0</doubles>
    <triples>0</triples>
    <home_runs>0</home_runs>
    <stolen_bases>0</stolen_bases>
    <caught_stealing>0</caught_stealing>
    <sacrifice_hits>0</sacrifice_hits>
    <sacrifice_flies>0</sacrifice_flies>
    <errors>0</errors>
    <passed_by_ball>0</passed_by_ball>
    <walks>0</walks>
    <strike_outs>6</strike_outs>
    <hit_by_pitch>0</hit_by_pitch>
  </player>
  <player>
    <first_name>Chad </first_name>
    <surname>Kreuter</surname>
    <games_played>96</games_played>
    <at_bats>252</at_bats>
    <runs>27</runs>
    <hits>63</hits>
    <doubles>10</doubles>
    <triples>1</triples>
    <home_runs>2</home_runs>
    <stolen_bases>33</stolen_bases>
    <caught_stealing>0</caught_stealing>
    <sacrifice_hits>5</sacrifice_hits>
    <sacrifice_flies>1</sacrifice_flies>
    <errors>9</errors>
    <passed_by_ball>5</passed_by_ball>
    <walks>33</walks>
    <strike_outs>49</strike_outs>
    <hit_by_pitch>3</hit_by_pitch>
  </player>
  <player>
    <first_name>Norberto </first_name>
    <surname>Martin</surname>
    <games_played>79</games_played>
    <at_bats>195</at_bats>
    <runs>20</runs>
    <hits>42</hits>
    <doubles>2</doubles>
    <triples>0</triples>
    <home_runs>1</home_runs>
    <stolen_bases>13</stolen_bases>
    <caught_stealing>1</caught_stealing>
    <sacrifice_hits>3</sacrifice_hits>
    <sacrifice_flies>2</sacrifice_flies>
    <errors>4</errors>
    <passed_by_ball>0</passed_by_ball>
    <walks>6</walks>
    <strike_outs>29</strike_outs>
    <hit_by_pitch>0</hit_by_pitch>
  </player>
  <player>
    <first_name>Damon </first_name>
    <surname>Mashore</surname>
    <games_played>43</games_played>
    <at_bats>98</at_bats>
    <runs>13</runs>
    <hits>23</hits>
    <doubles>6</doubles>
    <triples>0</triples>
    <home_runs>2</home_runs>
    <stolen_bases>11</stolen_bases>
    <caught_stealing>0</caught_stealing>
    <sacrifice_hits>1</sacrifice_hits>
    <sacrifice_flies>0</sacrifice_flies>
    <errors>0</errors>
    <passed_by_ball>0</passed_by_ball>
    <walks>9</walks>
    <strike_outs>22</strike_outs>
    <hit_by_pitch>3</hit_by_pitch>
  </player>
  <player>
    <first_name>Ben </first_name>
    <surname>Molina</surname>
    <games_played>2</games_played>
    <at_bats>1</at_bats>
    <runs>0</runs>
    <hits>0</hits>
    <doubles>0</doubles>
    <triples>0</triples>
    <home_runs>0</home_runs>
    <stolen_bases>0</stolen_bases>
    <caught_stealing>0</caught_stealing>
    <sacrifice_hits>0</sacrifice_hits>
    <sacrifice_flies>0</sacrifice_flies>
    <errors>0</errors>
    <passed_by_ball>0</passed_by_ball>
    <walks>0</walks>
    <strike_outs>0</strike_outs>
    <hit_by_pitch>0</hit_by_pitch>
  </player>
  <player>
    <first_name>Phil </first_name>
    <surname>Nevin</surname>
    <games_played>75</games_played>
    <at_bats>237</at_bats>
    <runs>27</runs>
    <hits>54</hits>
    <doubles>8</doubles>
    <triples>1</triples>
    <home_runs>8</home_runs>
    <stolen_bases>27</stolen_bases>
    <caught_stealing>0</caught_stealing>
    <sacrifice_hits>0</sacrifice_hits>
    <sacrifice_flies>2</sacrifice_flies>
    <errors>5</errors>
    <passed_by_ball>20</passed_by_ball>
    <walks>17</walks>
    <strike_outs>67</strike_outs>
    <hit_by_pitch>5</hit_by_pitch>
  </player>
  <player>
    <first_name>Charlie </first_name>
    <surname>Obrien</surname>
    <games_played>62</games_played>
    <at_bats>175</at_bats>
    <runs>13</runs>
    <hits>45</hits>
    <doubles>9</doubles>
    <triples>0</triples>
    <home_runs>4</home_runs>
    <stolen_bases>18</stolen_bases>
    <caught_stealing>0</caught_stealing>
    <sacrifice_hits>3</sacrifice_hits>
    <sacrifice_flies>3</sacrifice_flies>
    <errors>4</errors>
    <passed_by_ball>1</passed_by_ball>
    <walks>10</walks>
    <strike_outs>33</strike_outs>
    <hit_by_pitch>2</hit_by_pitch>
  </player>
  <player>
    <first_name>Orlando </first_name>
    <surname>Palmeiro</surname>
    <games_played>74</games_played>
    <at_bats>165</at_bats>
    <runs>28</runs>
    <hits>53</hits>
    <doubles>7</doubles>
    <triples>2</triples>
    <home_runs>0</home_runs>
    <stolen_bases>21</stolen_bases>
    <caught_stealing>4</caught_stealing>
    <sacrifice_hits>7</sacrifice_hits>
    <sacrifice_flies>0</sacrifice_flies>
    <errors>0</errors>
    <passed_by_ball>0</passed_by_ball>
    <walks>20</walks>
    <strike_outs>11</strike_outs>
    <hit_by_pitch>0</hit_by_pitch>
  </player>
  <player>
    <first_name>Chris </first_name>
    <surname>Pritchett</surname>
    <games_played>31</games_played>
    <at_bats>80</at_bats>
    <runs>12</runs>
    <hits>23</hits>
    <doubles>2</doubles>
    <triples>1</triples>
    <home_runs>2</home_runs>
    <stolen_bases>8</stolen_bases>
    <caught_stealing>0</caught_stealing>
    <sacrifice_hits>0</sacrifice_hits>
    <sacrifice_flies>0</sacrifice_flies>
    <errors>1</errors>
    <passed_by_ball>0</passed_by_ball>
    <walks>4</walks>
    <strike_outs>16</strike_outs>
    <hit_by_pitch>0</hit_by_pitch>
  </player>
  <player>
    <first_name>Tim </first_name>
    <surname>Salmon</surname>
    <games_played>136</games_played>
    <at_bats>463</at_bats>
    <runs>84</runs>
    <hits>139</hits>
    <doubles>28</doubles>
    <triples>1</triples>
    <home_runs>26</home_runs>
    <stolen_bases>88</stolen_bases>
    <caught_stealing>1</caught_stealing>
    <sacrifice_hits>0</sacrifice_hits>
    <sacrifice_flies>10</sacrifice_flies>
    <errors>2</errors>
    <passed_by_ball>0</passed_by_ball>
    <walks>90</walks>
    <strike_outs>100</strike_outs>
    <hit_by_pitch>3</hit_by_pitch>
  </player>
  <player>
    <first_name>Craig </first_name>
    <surname>Shipley</surname>
    <games_played>77</games_played>
    <at_bats>147</at_bats>
    <runs>18</runs>
    <hits>38</hits>
    <doubles>7</doubles>
    <triples>1</triples>
    <home_runs>2</home_runs>
    <stolen_bases>17</stolen_bases>
    <caught_stealing>4</caught_stealing>
    <sacrifice_hits>4</sacrifice_hits>
    <sacrifice_flies>1</sacrifice_flies>
    <errors>3</errors>
    <passed_by_ball>0</passed_by_ball>
    <walks>5</walks>
    <strike_outs>22</strike_outs>
    <hit_by_pitch>5</hit_by_pitch>
  </player>
  <player>
    <first_name>Randy </first_name>
    <surname>Velarde</surname>
    <games_played>51</games_played>
    <at_bats>188</at_bats>
    <runs>29</runs>
    <hits>49</hits>
    <doubles>13</doubles>
    <triples>1</triples>
    <home_runs>4</home_runs>
    <stolen_bases>26</stolen_bases>
    <caught_stealing>2</caught_stealing>
    <sacrifice_hits>0</sacrifice_hits>
    <sacrifice_flies>1</sacrifice_flies>
    <errors>4</errors>
    <passed_by_ball>0</passed_by_ball>
    <walks>34</walks>
    <strike_outs>42</strike_outs>
    <hit_by_pitch>1</hit_by_pitch>
  </player>
  <player>
    <first_name>Matt </first_name>
    <surname>Walbeck</surname>
    <games_played>108</games_played>
    <at_bats>338</at_bats>
    <runs>41</runs>
    <hits>87</hits>
    <doubles>15</doubles>
    <triples>2</triples>
    <home_runs>6</home_runs>
    <stolen_bases>46</stolen_bases>
    <caught_stealing>1</caught_stealing>
    <sacrifice_hits>5</sacrifice_hits>
    <sacrifice_flies>5</sacrifice_flies>
    <errors>7</errors>
    <passed_by_ball>8</passed_by_ball>
    <walks>30</walks>
    <strike_outs>68</strike_outs>
    <hit_by_pitch>2</hit_by_pitch>
  </player>
  <player>
    <first_name>Reggie </first_name>
    <surname>Williams</surname>
    <games_played>29</games_played>
    <at_bats>36</at_bats>
    <runs>7</runs>
    <hits>13</hits>
    <doubles>1</doubles>
    <triples>0</triples>
    <home_runs>1</home_runs>
    <stolen_bases>5</stolen_bases>
    <caught_stealing>3</caught_stealing>
    <sacrifice_hits>1</sacrifice_hits>
    <sacrifice_flies>0</sacrifice_flies>
    <errors>0</errors>
    <passed_by_ball>0</passed_by_ball>
    <walks>7</walks>
    <strike_outs>11</strike_outs>
    <hit_by_pitch>1</hit_by_pitch>
  </player>
</players>

A Shortcut

import java.io.*;
import org.jdom.*;
import org.jdom.output.XMLOutputter;


public class BaseballTabToXMLShortcut {

  public static void main(String[] args) {
     
    Element root = new Element("players");
    
    try {
      FileInputStream fin = new FileInputStream(args[0]);
      BufferedReader in 
       = new BufferedReader(new InputStreamReader(fin));    

      String playerStats;  
      while ((playerStats = in.readLine()) != null) {
        String[] stats = splitLine(playerStats);
        
        Element player = new Element("player");

        player.addContent((new Element("first_name")).setText(stats[1]));
        player.addContent((new Element("surname")).setText(stats[0]));
        player.addContent((new Element("games_played")).setText(stats[4]));
        player.addContent((new Element("at_bats")).setText(stats[6]));
        player.addContent((new Element("runs")).setText(stats[7]));
        player.addContent((new Element("hits")).setText(stats[8]));
        player.addContent((new Element("doubles")).setText(stats[9]));
        player.addContent((new Element("triples")).setText(stats[10]));
        player.addContent((new Element("home_runs")).setText(stats[11]));
        player.addContent((new Element("runs_batted_in")).setText(stats[12]));
        player.addContent((new Element("stolen_bases")).setText(stats[13]));
        player.addContent((new Element("caught_stealing")).setText(stats[14]));
        player.addContent((new Element("sacrifice_hits")).setText(stats[15]));
        player.addContent((new Element("sacrifice_flies")).setText(stats[16]));
        player.addContent((new Element("errors")).setText(stats[17]));
        player.addContent((new Element("passed_by_ball")).setText(stats[18]));
        player.addContent((new Element("walks")).setText(stats[19]));
        player.addContent((new Element("strike_outs")).setText(stats[20]));
        player.addContent((new Element("hit_by_pitch")).setText(stats[21]));
        
        root.addContent(player);
      }  
      
      Document doc = new Document(root);
      // serialize it into a file
      FileOutputStream fout 
       = new FileOutputStream("baseballstats.xml");
      
      XMLOutputter serializer = new XMLOutputter(); 
      serializer.output(doc, fout);
      fout.flush();	
      fout.close();
      in.close();
      
    }
    catch (IOException e) {
      System.err.println(e);
    }
    catch (ArrayIndexOutOfBoundsException e) {
      System.out.println(
       "Usage: java BaseballTabToXML input_file.tab");
    }

  }

  public static String[] splitLine(String playerStats) {
    
    // count the number of tabs
    int numTabs = 0;
    for (int i = 0; i < playerStats.length(); i++) {
      if (playerStats.charAt(i) == '\t') numTabs++;
    }
    int numFields = numTabs + 1;
    String[] fields = new String[numFields];
    int position = 0;
    for (int i = 0; i < numFields; i++) {
      StringBuffer field = new StringBuffer();
      while (position < playerStats.length() 
       && playerStats.charAt(position++) != '\t') {
        field.append(playerStats.charAt(position-1));
      }
      fields[i] = field.toString();
    }    
    return fields;
    
  }

}

Questions?

Converting data to XML while Processing it

import java.io.*;
import java.text.*;
import java.util.*;
import org.jdom.*;
import org.jdom.output.XMLOutputter;

public class BattingAverage {

  public static void main(String[] args) {
     
    Element root = new Element("players");
     
    try {
      FileInputStream fin = new FileInputStream(args[0]);
      BufferedReader in 
       = new BufferedReader(new InputStreamReader(fin));
      
      String playerStats;
      
      // for formatting batting averages
      DecimalFormat averages = (DecimalFormat) 
       NumberFormat.getNumberInstance(Locale.US);
      averages.setMaximumFractionDigits(3);
      averages.setMinimumFractionDigits(3);
      averages.setMinimumIntegerDigits(0);
      
      while ((playerStats = in.readLine()) != null) {
        String[] stats = splitLine(playerStats);
        
        String formattedAverage;
        try {
          int atBats         = Integer.parseInt(stats[6]);
          int hits           = Integer.parseInt(stats[8]);
          int walks          = Integer.parseInt(stats[19]);
          int hitByPitch     = Integer.parseInt(stats[21]);
          int sacrificeFlies = Integer.parseInt(stats[16]);
          int sacrificeHits  = Integer.parseInt(stats[15]);
        
          int officialAtBats 
           = atBats - walks - hitByPitch - sacrificeHits;
          if (officialAtBats <= 0) formattedAverage = "N/A";
          else {
            double average = hits / (double) officialAtBats;
            formattedAverage = averages.format(average);
          }       
        }
        catch (Exception e) {
          // skip this player
          continue; 
        }

        Element player = new Element("player");

        Element first_name = new Element("first_name");
        first_name.setText(stats[1]);
        player.addContent(first_name);
             
        Element surname = new Element("surname");
        surname.setText(stats[0]);
        player.addContent(surname);
       
        Element battingAverage = new Element("batting_average");
        battingAverage.setText(formattedAverage);
        player.addContent(battingAverage);
   
        root.addContent(player);
        
      }  
      
      
      Document doc = new Document(root);
      // serialize it into a file
      FileOutputStream fout 
       = new FileOutputStream("battingaverages.xml");
      
      XMLOutputter serializer = new XMLOutputter(); 
      serializer.output(doc, fout);
      fout.flush();	
      fout.close();
      in.close();

    }
    catch (IOException e) {
      System.err.println(e);
    }
    catch (ArrayIndexOutOfBoundsException e) {
      System.out.println("Usage: java BattingAverage input_file.tab");
    }

  }

  public static String[] splitLine(String playerStats) {
    
    // count the number of tabs
    int numTabs = 0;
    for (int i = 0; i < playerStats.length(); i++) {
      if (playerStats.charAt(i) == '\t') numTabs++;
    }
    int numFields = numTabs + 1;
    String[] fields = new String[numFields];
    int position = 0;
    for (int i = 0; i < numFields; i++) {
      StringBuffer field = new StringBuffer();
      while (position < playerStats.length() 
       && playerStats.charAt(position++) != '\t') {
        field.append(playerStats.charAt(position-1));
      }
      fields[i] = field.toString();
    }    
    return fields;
    
  }

}
View Output in Browser

Batting Averages in XML

<?xml version="1.0"?>
<players>
  <player>
    <first_name>Garret </first_name>
    <surname>Anderson</surname>
    <batting_average>.311</batting_average>
  </player>
  <player>
    <first_name>Justin </first_name>
    <surname>Baughman</surname>
    <batting_average>.272</batting_average>
  </player>
  <player>
    <first_name>Frank </first_name>
    <surname>Bolick</surname>
    <batting_average>.206</batting_average>
  </player>
  <player>
    <first_name>Gary </first_name>
    <surname>Disarcina</surname>
    <batting_average>.310</batting_average>
  </player>
  <player>
    <first_name>Jim </first_name>
    <surname>Edmonds</surname>
    <batting_average>.341</batting_average>
  </player>
  <player>
    <first_name>Darin </first_name>
    <surname>Erstad</surname>
    <batting_average>.326</batting_average>
  </player>
  <player>
    <first_name>Carlos </first_name>
    <surname>Garcia</surname>
    <batting_average>.167</batting_average>
  </player>
  <player>
    <first_name>Troy </first_name>
    <surname>Glaus</surname>
    <batting_average>.240</batting_average>
  </player>
  <player>
    <first_name>Todd </first_name>
    <surname>Greene</surname>
    <batting_average>.261</batting_average>
  </player>
  <player>
    <first_name>Eric </first_name>
    <surname>Helfand</surname>
    <batting_average>N/A</batting_average>
  </player>
  <player>
    <first_name>Dave </first_name>
    <surname>Hollins</surname>
    <batting_average>.284</batting_average>
  </player>
  <player>
    <first_name>Gregg </first_name>
    <surname>Jefferies</surname>
    <batting_average>.347</batting_average>
  </player>
  <player>
    <first_name>Mark </first_name>
    <surname>Johnson</surname>
    <batting_average>.071</batting_average>
  </player>
  <player>
    <first_name>Chad </first_name>
    <surname>Kreuter</surname>
    <batting_average>.299</batting_average>
  </player>
  <player>
    <first_name>Norberto </first_name>
    <surname>Martin</surname>
    <batting_average>.226</batting_average>
  </player>
  <player>
    <first_name>Damon </first_name>
    <surname>Mashore</surname>
    <batting_average>.271</batting_average>
  </player>
  <player>
    <first_name>Ben </first_name>
    <surname>Molina</surname>
    <batting_average>.000</batting_average>
  </player>
  <player>
    <first_name>Phil </first_name>
    <surname>Nevin</surname>
    <batting_average>.251</batting_average>
  </player>
  <player>
    <first_name>Charlie </first_name>
    <surname>Obrien</surname>
    <batting_average>.281</batting_average>
  </player>
  <player>
    <first_name>Orlando </first_name>
    <surname>Palmeiro</surname>
    <batting_average>.384</batting_average>
  </player>
  <player>
    <first_name>Chris </first_name>
    <surname>Pritchett</surname>
    <batting_average>.303</batting_average>
  </player>
  <player>
    <first_name>Tim </first_name>
    <surname>Salmon</surname>
    <batting_average>.376</batting_average>
  </player>
  <player>
    <first_name>Craig </first_name>
    <surname>Shipley</surname>
    <batting_average>.286</batting_average>
  </player>
  <player>
    <first_name>Randy </first_name>
    <surname>Velarde</surname>
    <batting_average>.320</batting_average>
  </player>
  <player>
    <first_name>Matt </first_name>
    <surname>Walbeck</surname>
    <batting_average>.289</batting_average>
  </player>
  <player>
    <first_name>Reggie </first_name>
    <surname>Williams</surname>
    <batting_average>.481</batting_average>
  </player>
</players>

Advantages of JDOM for Writing Documents

Questions?

Reading XML with JDOM

JDOM Compatible Parsers for Java

Any SAX or DOM compatible parser including:

The Design of the DOM API

The JDOM Process

Parsing a Document with JDOM

import org.jdom.JDOMException;
import org.jdom.input.SAXBuilder;


public class JDOMChecker {

  public static void main(String[] args) {
  
    if (args.length == 0) {
      System.out.println("Usage: java JDOMChecker URL1 URL2..."); 
    } 
      
    SAXBuilder builder = new SAXBuilder();
     
    // start parsing... 
    for (int i = 0; i < args.length; i++) {
      
      // command line should offer URIs or file names
      try {
        builder.build(args[i]);
        // If there are no well-formedness errors, 
        // then no exception is thrown
        System.out.println(args[i] + " is well formed.");
      }
             // indicates a well-formedness or other error
      catch (JDOMException e) { 
        System.out.println(args[i] + " is not well formed.");
        System.out.println(e.getMessage());
      }
      
    }   
  
  }

}

Parser Results

% java JDOMChecker shortlogs.xml HelloJDOM.java
shortlogs.xml is well formed.
HelloJDOM.java is not well formed.
The markup in the document preceding the root element must be well-formed.: 
Error on line 1 of XML document: The markup in the document preceding the 
root element must be well-formed.

Turning on Validation in JDOM

JDOM Validator

import org.xml.sax.*;
import org.xml.sax.helpers.*;
import java.io.*;


public class JDOMValidator {

  public static void main(String[] args) {

    XMLReader parser;
    try {
     parser = XMLReaderFactory.createXMLReader();
    }
    catch (Exception e) {
      // fall back on Xerces parser by name
      try {
        parser = XMLReaderFactory.createXMLReader(
         "org.apache.xerces.parsers.SAXParser");
      }
      catch (Exception ee) {
        System.err.println("Couldn't locate a SAX parser");
        return;
      }
    }

    // turn on validation
    try {
      parser.setFeature(
       "http://xml.org/sax/features/validation", true);
      parser.setErrorHandler(new ValidityErrorReporter());
    }
    catch (SAXNotRecognizedException e) {
      System.err.println(
       "Installed XML parser cannot validate;"
       + " checking for well-formedness instead...");
    }
    catch (SAXNotSupportedException e) {
      System.err.println(
       "Cannot turn on validation here; "
       + "checking for well-formedness instead...");
    }

    if (args.length == 0) {
      System.out.println("Usage: java JDOMValidator URL1 URL2...");
    }

    // start parsing...
    for (int i = 0; i < args.length; i++) {

      // command line should offer URIs or file names
      try {
        parser.parse(args[i]);
        // If there are no well-formedness errors,
        // then no exception is thrown
        System.out.println(args[i] + " is well formed.");
      }
      catch (SAXParseException e) { // well-formedness error
        System.out.println(args[i] + " is not well formed.");
        System.out.println(e.getMessage()
         + " at line " + e.getLineNumber()
         + ", column " + e.getColumnNumber());
      }
      catch (SAXException e) { // some other kind of error
        System.out.println(e.getMessage());
      }
      catch (IOException e) {
        System.out.println("Could not check " + args[i]
         + " because of the IOException " + e);
      }

    }

  }

}

Validation Output

% java JDOMValidator invalid_fibonacci.xml
invalid_fibonacci.xml is not valid.
Element type "title" must be declared.: Error on line 8 of XML document: 
Element type "title" must be declared.

% java JDOMValidator validfibonacci.xml
validfibonacci.xml is valid.

Building with DOM instead of SAX

DOMBuilder Example

import org.jdom.*;
import org.jdom.input.DOMBuilder;
import org.apache.xerces.parsers.*;


public class DOMValidator {

  public static void main(String[] args) {
  
    if (args.length == 0) {
      System.out.println("Usage: java DOMValidator URL1 URL2..."); 
    }      
      
    DOMBuilder builder = new DOMBuilder(true);
                             /*         ^^^^       */
                             /* Turn on validation */
    // start parsing... 
    DOMParser parser = new DOMParser();  // Xerces specific class
    for (int i = 0; i < args.length; i++) {
        
      try {
        // Read the entire document into memory
        parser.parse(args[i]); 
    
        org.w3c.dom.Document domDoc  = parser.getDocument();
        org.jdom.Document    jdomDoc = builder.build(domDoc);

        // If there are no validity errors, 
        // then no exception is thrown
        System.out.println(args[i] + " is valid.");
      }
             // indicates a well-formedness or validity error
      catch (Exception e) { 
        System.out.println(args[i] + " is not valid.");
        System.out.println(e.getMessage());
      }
      
    }   
  
  }

}

Weblogs with JDOM

Full list

Goal: Return a list of all the URLs in this list as java.net.URL objects

Design Decisions

JDOM Design

Weblogs with JDOM

import org.jdom.*;
import org.jdom.input.SAXBuilder;
import java.util.*;
import java.net.*;


public class WeblogsJDOM {
   
  public static String DEFAULT_SYSTEM_ID 
   = "http://static.userland.com/weblogMonitor/logs.xml"; 
     
  public static List listChannels() throws JDOMException {
    return listChannels(DEFAULT_SYSTEM_ID); 
  }
  
  public static List listChannels(String systemID) 
   throws JDOMException, NullPointerException {
    
    if (systemID == null) {
      throw new NullPointerException("URL must be non-null");   
    }
    
    SAXBuilder builder = new SAXBuilder();
    // Load the entire document into memory 
    // from the network or file system
    Document doc = builder.build(systemID);
    
    // Descend the tree and find the URLs. It helps that
    // the document has a very regular structure.
    Element weblogs = doc.getRootElement();
    List logs = weblogs.getChildren("log");
    Vector urls = new Vector(logs.size());
    Iterator iterator = logs.iterator();
    while (iterator.hasNext()) {
      Object o = iterator.next();
      Element log = (Element) o;
      try {
                         // This will probably be changed to 
                         //  getElement() or getChildElement() 
        Element url = log.getChild("url"); 
        if (url == null) continue;
        String content = url.getTextTrim();
        URL u = new URL(content);
        urls.addElement(u);
      }
      catch (MalformedURLException e) {
        // bad input data from one third party; just ignore it 
      }
    }
    return urls;
    
  }
  
  public static void main(String[] args) {
   
    try {
      List urls;
      if (args.length > 0) {
        urls = listChannels(args[0]);
      }
      else {
        urls = listChannels();
      }
      Iterator iterator = urls.iterator();
      while (iterator.hasNext()) {
        System.out.println(iterator.next()); 
      }
    }
    catch (/* Unexpected */ Exception e) {
      e.printStackTrace(); 
    }
    
  }
  
}

Weblogs Output

% java WeblogsJDOM
http://2020Hindsight.editthispage.com/
http://www.sff.net/people/mitchw/weblog/weblog.htp
http://nate.weblogs.com/
http://plugins.launchpoint.net
http://404.psistorm.net
http://home.att.net/~geek9000
http://daubnet.tzo.com/weblog
several hundred more...

The org.jdom Package

The classes that represent an XML document and its parts

The Document Node

The Document Class

package org.jdom;

public class Document implements Serializable, Cloneable {

  protected List    content;
  protected Element rootElement;
  protected DocType docType;

  protected Document() {}
  public    Document(Element rootElement) {}
  public    Document(Element rootElement, DocType docType) {}

  public Element   getRootElement() {}
  public Document  setRootElement(Element rootElement) {}
  public DocType   getDocType() {}
  public Document  setDocType(DocType docType) {}
  public List      getProcessingInstructions() {}
  public List      getProcessingInstructions(String target) {}
  public ProcessingInstruction getProcessingInstruction(String target)
    throws NoSuchProcessingInstructionException {}
  public Document  addProcessingInstruction(ProcessingInstruction pi) {}
  public Document  addProcessingInstruction(String target, String data) {}
  public Document  addProcessingInstruction(String target, Map data) {}
  public Document  setProcessingInstructions(List processingInstructions) {}
  public boolean   removeProcessingInstruction(ProcessingInstruction processingInstruction) {}
  public boolean   removeProcessingInstruction(String target) {}
  public boolean   removeProcessingInstructions(String target) {}
  public Document  addComment(Comment comment) {}
  public List      getMixedContent() {}
  
  // basic utility methods
  public final String  toString() {}
  public final String  getSerializedForm() {}  // going away
  public final boolean equals(Object ob) {}
  public final int     hashCode() {}
  public final Object  clone() {}

}

Document Example

import org.jdom.Document;
import org.jdom.JDOMException;
import org.jdom.input.SAXBuilder;
import org.jdom.output.XMLOutputter;
import java.io.IOException;


public class XMLPrinter {

  public static void main(String[] args) {
  
    if (args.length == 0) {
      System.out.println("Usage: java XMLPrinter URL1 URL2..."); 
    } 
      
    SAXBuilder builder = new SAXBuilder();
     
    // start parsing... 
    for (int i = 0; i < args.length; i++) {
      
      // command line should offer URIs or file names
      try {
        Document doc = builder.build(args[i]);
        System.out.println("*************" + args[i] 
         + "*************");
        XMLOutputter outputter = new XMLOutputter();
        outputter.output(doc, System.out);
      }
      // indicates a well-formedness or other error
      catch (JDOMException e) { 
        System.out.println(args[i] + " is not well formed.");
        System.out.println(e.getMessage());
      }
      // shouldn't happen because System.out eats exceptions
      catch (IOException e) { 
        System.out.println(e.getMessage());
      }
      
    }   
  
  }

}

Output from XMLPrinter

% java XMLPrinter shortlogs.xml
*************shortlogs.xml*************
<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE foo SYSTEM "http://msdn.microsoft.com/xml/general/htmlentities.dtd"><weblogs>
        <log>
                <name>MozillaZine</name>
                <url>http://www.mozillazine.org</url>
                <changesUrl>http://www.mozillazine.org/contents.rdf</changesUrl>

                <ownerName>Jason Kersey</ownerName>
                <ownerEmail>kerz@en.com</ownerEmail>
                <description>THE source for news on the Mozilla Organization.  DevChats, Reviews, Chats, Builds, Demos, Screenshots, and more.</description>
                <imageUrl />
                <adImageUrl>http://static.userland.com/weblogMonitor/ads/kerz@en.com.gif</adImageUrl>
                </log>
        <log>
                <name>SalonHerringWiredFool</name>
                <url>http://www.salonherringwiredfool.com/</url>
                <ownerName>Some Random Herring</ownerName>
                <ownerEmail>salonfool@wiredherring.com</ownerEmail>
                <description />
                </log>
        <log>
                <name>SlashDot.Org</name>
                <url>http://www.slashdot.org/</url>
                <ownerName>Simply a friend</ownerName>
                <ownerEmail>afriendofweblogs@weblogs.com</ownerEmail>
                <description>News for Nerds, Stuff that Matters.</description>
                </log>
        </weblogs>

Element Nodes

Element Class Implementation

The Element Class

package org.jdom;

public class Element implements Serializable, Cloneable {

    protected String    name;
    protected Namespace namespace;
    protected Element   parent;
    protected boolean   isRootElement;
    protected List      attributes;
    protected List      content;

    protected Element() {}
    public    Element(String name, Namespace namespace) {}
    public    Element(String name) {}
    public    Element(String name, String uri) {}
    public    Element(String name, String prefix, String uri) {}

    public String     getName() {}
    public Namespace  getNamespace() {}
    public String     getNamespacePrefix() {}
    public String     getNamespaceURI() {}
    public String     getQualifiedName() {}
    
    public Element    getParent() {}
    protected Element setParent(Element parent) {}
    public boolean    isRootElement() {}
    protected Element setIsRootElement(boolean isRootElement) {}
    

    public String    getText() {} 
    public String    getTextTrim() {} 
    public boolean   hasMixedContent() {} 
    public List      getMixedContent() {}
    public String    getChildText(String name) {} 
    public String    getChildTextTrim(String name) {} 
    public String    getChildText(String name, Namespace ns) {} 

    public Element   setMixedContent(List mixedContent) {} 
    public List      getChildren() {} 
    public Element   setChildren(List children) {} 
    public List      getChildren(String name, Namespace ns) {} 
    // will be renamed, probably getElement() {}
    public Element   getChild(String name, Namespace ns) {} 
    public Element   getChild(String name) {} 
    public boolean   removeChild(String name) {} 
    public boolean   removeChild(String name, Namespace ns) {} 
    public boolean   removeChildren(String name) {}
    public boolean   removeChildren(String name, Namespace ns) {} 
    public boolean   removeChildren() {} 
    
    public Element   addContent(String text) {}
    public Element   addContent(Element element) {} 
    public Element   addContent(ProcessingInstruction pi) {} 
    public Element   addContent(Entity entity) {} 
    public Element   addContent(Comment comment) {} 
    public Element   addContent(CDATA cdata) {} 
    public boolean   removeContent(Element element) {} 
    public boolean   removeContent(ProcessingInstruction pi) {} 
    public boolean   removeContent(Entity entity) {} 
    public boolean   removeContent(Comment comment) {} 
    
    public List      getAttributes() {} 
    public Attribute getAttribute(String name) {} 
    public Attribute getAttribute(String name, Namespace ns) {} 
    public String    getAttributeValue(String name) {} 
    public String    getAttributeValue(String name, Namespace ns) {} 
    public Element   setAttributes(List attributes) {} 
    public Element   addAttribute(Attribute attribute) {}
    public Element   addAttribute(String name, String value) {} 
    public boolean   removeAttribute(String name, String uri) {} 
    public boolean   removeAttribute(String name) {} 
    public boolean   removeAttribute(String name, Namespace ns) {} 
    
    public Element   getCopy(String name, Namespace ns) {}
    public Element   getCopy(String name, String uri) {}
    public Element   getCopy(String name, String prefix, String uri) {}

    ///////////////////////////////////////
    // Basic Utility Methods
    /////////////////////////////////////// 
    public final String  toString() {}
    public final boolean equals(Object ob) {}
    public final int     hashCode() {}
    public final Object  clone() {}
    
}

Element Example: XCount

import org.jdom.*;
import org.jdom.input.SAXBuilder;
import java.util.*;


public class XCount {

  public static void main(String[] args) {
  
    if (args.length == 0) {
      System.out.println("Usage: java XCount URL1 URL2..."); 
    } 
      
    SAXBuilder builder = new SAXBuilder();
     
    System.out.println(
     "File\tElements\tAttributes\tComments\tProcessing Instructions\tCharacters");
    // start parsing... 
    for (int i = 0; i < args.length; i++) {
      
      // command line should offer URIs or file names
      try {
        Document doc = builder.build(args[i]);
        System.out.print(args[i] + ":\t");
        String result = count(doc);
        System.out.println(result);
      }
             // indicates a well-formedness or other error
      catch (JDOMException e) { 
        System.out.println(args[i] 
         + " is not a well formed XML document.");
        System.out.println(e.getMessage());
      }
      
    }   
  
  }  

  private static int numCharacters             = 0;
  private static int numComments               = 0;
  private static int numElements               = 0;
  private static int numAttributes             = 0;
  private static int numProcessingInstructions = 0;
      
  public static String count(Document doc) {

    numCharacters = 0;
    numComments = 0;
    numElements = 0;
    numAttributes = 0;
    numProcessingInstructions = 0;  

    List children = doc.getMixedContent();
    Iterator iterator = children.iterator();
    while (iterator.hasNext()) {
      Object o = iterator.next();
      if (o instanceof Element) {
        numElements++;
        count((Element) o);
      }
      else if (o instanceof Comment) numComments++;
      else if (o instanceof ProcessingInstruction) {
        numProcessingInstructions++;   
      }
    }
    
    String result = numElements + "\t" + numAttributes + "\t" 
     + numComments + "\t" + numProcessingInstructions + "\t" 
     + numCharacters;
    return result;
       
  }     

  public static void count(Element element) {

    List attributes = element.getAttributes();
    numAttributes += attributes.size();
    List children = element.getMixedContent();
    Iterator iterator = children.iterator();
    while (iterator.hasNext()) {
      Object o = iterator.next();
      if (o instanceof Element) {
        numElements++;
        count((Element) o);
      }
      else if (o instanceof Comment) numComments++;
      else if (o instanceof ProcessingInstruction) {
        numProcessingInstructions++;   
      }
      else if (o instanceof String) {
        String s = (String) o;
        numCharacters += s.length();
      }   
    }
        
  }  

}

XCount Output

% java XCount shortlogs.xml hotcop.xml
File    Elements        Attributes      Comments        Processing Instructions
Characters
shortlogs.xml:  30      0       0       0       736
hotcop.xml:     11      8       2       1       95

Handling Attributes in JDOM

The Attribute Class

package org.jdom;

public class Attribute implements Serializable, Cloneable {

    protected String    name;
    protected Namespace namespace;
    protected String    value;

    protected Attribute() {}
    public    Attribute(String name, String value, Namespace namespace) {}
    public    Attribute(String name, String prefix, String uri, String value) {}
    public    Attribute(String name, String value) {}

    public String    getName() {}
    public String    getQualifiedName() {}
    public String    getNamespacePrefix() {}
    public String    getNamespaceURI() {}
    public Namespace getNamespace() {}
    public String    getValue() {}
    public void      setValue(String value) {}

    /////////////////////////////////////////////////////////////////
    // Basic Utility Methods
    /////////////////////////////////////////////////////////////////

    public final String  toString() {}
    public final boolean equals(Object ob) {}
    public final int     hashCode() {}
    public final Object  clone() {}

    /////////////////////////////////////////////////////////////////
    // Convenience Methods below here
    /////////////////////////////////////////////////////////////////

    public String  getValue(String defaultValue) {}
    public int     getIntValue(int defaultValue) {}
    public int     getIntValue() throws DataConversionException {}
    public long    getLongValue(long defaultValue) {}
    public long    getLongValue() throws DataConversionException {}
    public float   getFloatValue(float defaultValue) {}
    public float   getFloatValue() throws DataConversionException {}
    public double  getDoubleValue(double defaultValue) {}
    public double  getDoubleValue() throws DataConversionException {}
    public boolean getBooleanValue(boolean defaultValue) {}
    public boolean getBooleanValue() throws DataConversionException {}
    public char    getCharValue(char defaultValue) {}
    public char    getCharValue() throws DataConversionException {}

}

IDTagger

import java.io.IOException;
import org.jdom.*;
import org.jdom.input.SAXBuilder;
import org.jdom.output.XMLOutputter;
import java.util.*;


public class JDOMIDTagger {

  private static int id = 1;

  public static void processElement(Element element) {

    if (element.getAttribute("ID") == null) {
      element.addAttribute(new Attribute("ID", "_" + id));
      id = id + 1; 
    }
    
    // recursion
    List children = element.getChildren();
    Iterator iterator = children.iterator();
    while (iterator.hasNext()) {
      processElement((Element) iterator.next());   
    }
    
  }

  public static void main(String[] args) {
     
    SAXBuilder builder = new SAXBuilder();
    
    for (int i = 0; i < args.length; i++) {
        
      try {
        // Read the entire document into memory
        Document document = builder.build(args[i]); 
       
        processElement(document.getRootElement());
        
        // now we serialize the document...
        XMLOutputter serializer = new XMLOutputter(); 
        serializer.output(document, System.out);
        System.out.flush();	        
      }
      catch (JDOMException e) {
        System.err.println(e);
        continue; 
      }
      catch (IOException e) {
        System.err.println(e);
        continue; 
      }
      
    }
  
  } // end main

}

Before IDTagger

<?xml version="1.0"?><backslash
xmlns:backslash="http://slashdot.org/backslash.dtd">

 <story>
    <title>The Onion to buy the New York Times</title>
    <url>http://slashdot.org/articles/00/02/19/1128240.shtml</url>
    <time>2000-02-19 17:25:15</time>
    <author>CmdrTaco</author>
    <department>stuff-to-read</department>
    <topic>media</topic>
    <comments>20</comments>
    <section>articles</section>
    <image>topicmedia.gif</image>
  </story>
 <story>
    <title>Al Gore's Webmaster Answers Your Questions</title>
    <url>http://slashdot.org/interviews/00/02/19/0932207.shtml</url>
    <time>2000-02-19 17:00:52</time>
    <author>Roblimo</author>
    <department>political-process-online</department>
    <topic>usa</topic>
    <comments>49</comments>
    <section>interviews</section>
    <image>topicus.gif</image>
  </story>
 <story>
    <title>Open Source Africa</title>
    <url>http://slashdot.org/articles/00/02/19/1016216.shtml</url>
    <time>2000-02-19 16:05:58</time>
    <author>emmett</author>
    <department>songs-by-toto</department>
    <topic>linux</topic>
    <comments>50</comments>
    <section>articles</section>
    <image>topiclinux.gif</image>
  </story>
 <story>
    <title>Microsoft Funded by NSA, Helps Spy on Win Users?</title>
    <url>http://slashdot.org/articles/00/02/19/0750247.shtml</url>
    <time>2000-02-19 14:07:04</time>
    <author>Roblimo</author>
    <department>deep-dark-conspiracy-theories</department>
    <topic>microsoft</topic>
    <comments>154</comments>
    <section>articles</section>
    <image>topicms.gif</image>
  </story>
 <story>
    <title>X-Men Trailer Released</title>
    <url>http://slashdot.org/articles/00/02/18/0829209.shtml</url>
    <time>2000-02-19 13:47:06</time>
    <author>emmett</author>
    <department>mutant</department>
    <topic>movies</topic>
    <comments>70</comments>
    <section>articles</section>
    <image>topicmovies.gif</image>
  </story>
 <story>
    <title>Connell Replies to "Grok" Comments</title>
    <url>http://slashdot.org/articles/00/02/18/202240.shtml</url>
    <time>2000-02-19 05:01:37</time>
    <author>Hemos</author>
    <department>replying-to-things</department>
    <topic>linux</topic>
    <comments>197</comments>
    <section>articles</section>
    <image>topiclinux.gif</image>
  </story>
 <story>
    <title>etoy.com Returns</title>
    <url>http://slashdot.org/yro/00/02/18/1739216.shtml</url>
    <time>2000-02-19 02:35:06</time>
    <author>nik</author>
    <department>NP:-gimme-shelter</department>
    <topic>internet</topic>
    <comments>77</comments>
    <section>yro</section>
    <image>topicinternet.jpg</image>
  </story>
 <story>
    <title>New Propaganda Series: Rebirth</title>
    <url>http://slashdot.org/articles/00/02/18/205232.shtml</url>
    <time>2000-02-19 01:05:26</time>
    <author>Hemos</author>
    <department>as-pretty-as-always</department>
    <topic>graphics</topic>
    <comments>120</comments>
    <section>articles</section>
    <image>topicgraphics3.gif</image>
  </story>
 <story>
    <title>Giving Back</title>
    <url>http://slashdot.org/features/00/02/18/1631224.shtml</url>
    <time>2000-02-18 22:27:26</time>
    <author>emmett</author>
    <department>salvation-army</department>
    <topic>news</topic>
    <comments>122</comments>
    <section>features</section>
    <image>topicnews.gif</image>
  </story>
 <story>
    <title>Connectix Considering Open Sourcing VGS?</title>
    <url>http://slashdot.org/articles/00/02/18/1050225.shtml</url>
    <time>2000-02-18 20:46:20</time>
    <author>emmett</author>
    <department>grain-of-salt</department>
    <topic>news</topic>
    <comments>93</comments>
    <section>articles</section>
    <image>topicnews.gif</image>
  </story>
</backslash>
View Input in Browser

After IDTagger

<?xml version="1.0" encoding="UTF-8"?>
<backslash ID="_1">
  <story ID="_2">
    <title ID="_3">The Onion to buy the New York Times</title>
    <url ID="_4">http://slashdot.org/articles/00/02/19/1128240.shtml</url>
    <time ID="_5">2000-02-19 17:25:15</time>
    <author ID="_6">CmdrTaco</author>
    <department ID="_7">stuff-to-read</department>
    <topic ID="_8">media</topic>
    <comments ID="_9">20</comments>
    <section ID="_10">articles</section>
    <image ID="_11">topicmedia.gif</image>
  </story>
  <story ID="_12">
    <title ID="_13">Al Gore's Webmaster Answers Your Questions</title>
    <url ID="_14">http://slashdot.org/interviews/00/02/19/0932207.shtml</url>
    <time ID="_15">2000-02-19 17:00:52</time>
    <author ID="_16">Roblimo</author>
    <department ID="_17">political-process-online</department>
    <topic ID="_18">usa</topic>
    <comments ID="_19">49</comments>
    <section ID="_20">interviews</section>
    <image ID="_21">topicus.gif</image>
  </story>
  <story ID="_22">
    <title ID="_23">Open Source Africa</title>
    <url ID="_24">http://slashdot.org/articles/00/02/19/1016216.shtml</url>
    <time ID="_25">2000-02-19 16:05:58</time>
    <author ID="_26">emmett</author>
    <department ID="_27">songs-by-toto</department>
    <topic ID="_28">linux</topic>
    <comments ID="_29">50</comments>
    <section ID="_30">articles</section>
    <image ID="_31">topiclinux.gif</image>
  </story>
  <story ID="_32">
    <title ID="_33">Microsoft Funded by NSA, Helps Spy on Win Users?</title>
    <url ID="_34">http://slashdot.org/articles/00/02/19/0750247.shtml</url>
    <time ID="_35">2000-02-19 14:07:04</time>
    <author ID="_36">Roblimo</author>
    <department ID="_37">deep-dark-conspiracy-theories</department>
    <topic ID="_38">microsoft</topic>
    <comments ID="_39">154</comments>
    <section ID="_40">articles</section>
    <image ID="_41">topicms.gif</image>
  </story>
  <story ID="_42">
    <title ID="_43">X-Men Trailer Released</title>
    <url ID="_44">http://slashdot.org/articles/00/02/18/0829209.shtml</url>
    <time ID="_45">2000-02-19 13:47:06</time>
    <author ID="_46">emmett</author>
    <department ID="_47">mutant</department>
    <topic ID="_48">movies</topic>
    <comments ID="_49">70</comments>
    <section ID="_50">articles</section>
    <image ID="_51">topicmovies.gif</image>
  </story>
  <story ID="_52">
    <title ID="_53">Connell Replies to "Grok" Comments</title>
    <url ID="_54">http://slashdot.org/articles/00/02/18/202240.shtml</url>
    <time ID="_55">2000-02-19 05:01:37</time>
    <author ID="_56">Hemos</author>
    <department ID="_57">replying-to-things</department>
    <topic ID="_58">linux</topic>
    <comments ID="_59">197</comments>
    <section ID="_60">articles</section>
    <image ID="_61">topiclinux.gif</image>
  </story>
  <story ID="_62">
    <title ID="_63">etoy.com Returns</title>
    <url ID="_64">http://slashdot.org/yro/00/02/18/1739216.shtml</url>
    <time ID="_65">2000-02-19 02:35:06</time>
    <author ID="_66">nik</author>
    <department ID="_67">NP:-gimme-shelter</department>
    <topic ID="_68">internet</topic>
    <comments ID="_69">77</comments>
    <section ID="_70">yro</section>
    <image ID="_71">topicinternet.jpg</image>
  </story>
  <story ID="_72">
    <title ID="_73">New Propaganda Series: Rebirth</title>
    <url ID="_74">http://slashdot.org/articles/00/02/18/205232.shtml</url>
    <time ID="_75">2000-02-19 01:05:26</time>
    <author ID="_76">Hemos</author>
    <department ID="_77">as-pretty-as-always</department>
    <topic ID="_78">graphics</topic>
    <comments ID="_79">120</comments>
    <section ID="_80">articles</section>
    <image ID="_81">topicgraphics3.gif</image>
  </story>
  <story ID="_82">
    <title ID="_83">Giving Back</title>
    <url ID="_84">http://slashdot.org/features/00/02/18/1631224.shtml</url>
    <time ID="_85">2000-02-18 22:27:26</time>
    <author ID="_86">emmett</author>
    <department ID="_87">salvation-army</department>
    <topic ID="_88">news</topic>
    <comments ID="_89">122</comments>
    <section ID="_90">features</section>
    <image ID="_91">topicnews.gif</image>
  </story>
  <story ID="_92">
    <title ID="_93">Connectix Considering Open Sourcing VGS?</title>
    <url ID="_94">http://slashdot.org/articles/00/02/18/1050225.shtml</url>
    <time ID="_95">2000-02-18 20:46:20</time>
    <author ID="_96">emmett</author>
    <department ID="_97">grain-of-salt</department>
    <topic ID="_98">news</topic>
    <comments ID="_99">93</comments>
    <section ID="_100">articles</section>
    <image ID="_101">topicnews.gif</image>
  </story>
</backslash>
View Output in Browser

Handling Entities in JDOM

The Entity Class

package org.jdom;

public class Entity implements Serializable, Cloneable {

    protected String name;
    protected List   content;

    protected Entity() {}
    public    Entity(String name) {}
    
    public String  getName() {}
    public String  getContent() {}
    public Entity  setContent(String textContent) {}
    public boolean hasMixedContent() {}
    public List    getMixedContent() {}
    public Entity  setMixedContent(List mixedContent) {}
    public List    getChildren() {}
    public Entity  setChildren(List children) {}
    public Entity  addChild(Element element) {}
    public Entity  addChild(String s) {}
    public Entity  addText(String text) {}
    
    public final String  toString() {}
    public final boolean equals(Object ob) {}
    public final int     hashCode() {}
    public final Object  clone() {}

}

Handling Comments in JDOM

The Comment Class

package org.jdom;

public class Comment implements Serializable, Cloneable {

    protected String text;

    protected Comment() {}
    public    Comment(String text) {}
    
    public String getText() {}
    public void   setText(String text) {}
    
    public final String  toString() {}
    public final boolean equals(Object ob) {}
    public final int     hashCode() {}
    public final Object  clone() {}

}

Comment Example

import org.jdom.*;
import org.jdom.input.SAXBuilder;
import java.util.*;


public class CommentReader {

  public static void main(String[] args) {
     
    SAXBuilder builder = new SAXBuilder();
    
    for (int i = 0; i < args.length; i++) {
      try {
        // Read the entire document into memory
        Document doc = builder.build(args[i]);
        List content = doc.getMixedContent();
        Iterator iterator = content.iterator();
        while (iterator.hasNext()) {
          Object o = iterator.next();
          if (o instanceof Comment) {
            Comment c = (Comment) o;
            System.out.println(c.getText());     
            System.out.println();     
          }
          else if (o instanceof Element) {
            processElement((Element) o);   
          }
        }
      }
      catch (JDOMException e) {
        System.err.println(e); 
        e.getRootCause().printStackTrace(); 
      }
      
    }
  
  } // end main

  // note use of recursion
  public static void processElement(Element element) {
    
    List content = element.getMixedContent();
    Iterator iterator = content.iterator();
    while (iterator.hasNext()) {
      Object o = iterator.next();
      if (o instanceof Comment) {
        Comment c = (Comment) o;
        System.out.println(c.getText());     
        System.out.println();     
      }
      else if (o instanceof Element) {
        processElement((Element) o);   
      }
    } // end while
    
  }

}

CommentReader Output

% java CommentReader hotcop.xml
 The publisher is actually Polygram but I needed
       an example of a general entity reference.

 You can tell what album I was
     listening to when I wrote this example

ProcessingInstruction Nodes

The ProcessingInstruction Class

package org.jdom;

public class ProcessingInstruction implements Serializable, Cloneable {

    protected String target;
    protected String rawData;
    protected Map    mapData;

    protected ProcessingInstruction() {}
    public    ProcessingInstruction(String target, Map data) {}
    public    ProcessingInstruction(String target, String data) {}
    
    public String                getTarget() {}
    public String                getData() {}
    public ProcessingInstruction setData(String data) {}
    public ProcessingInstruction setData(Map data) {}
    public String                getValue(String name) {}
    public ProcessingInstruction setValue(String name, String value) {}
    public boolean               removeValue(String name) {}

    public final String  toString() {}
    public final boolean equals(Object ob) {}
    public final int     hashCode() {}
    public final Object  clone() {}
}

XLinkSpider that Respects the robots Processing Instruction

import java.io.*;
import java.util.*;
import org.jdom.*;
import org.jdom.input.SAXBuilder;


public class XLinkSpider {

  private static SAXBuilder builder = new SAXBuilder();
  
  private static Vector visited = new Vector();
  
  private static int maxDepth = 5;
  private static int currentDepth = 0; 
  
  public static void listURIs(String systemID) {
    
    currentDepth++;
    try {
      if (currentDepth < maxDepth) {

        Document document = builder.build(systemID); 
                
        // check to see if we're allowed to spider
        boolean index = true;
        boolean follow = true;
        ProcessingInstruction robots 
         = document.getProcessingInstruction("robots");
        if (robots != null) {
          String indexValue = robots.getValue("index");
          if (indexValue.equalsIgnoreCase("no")) index = false;
          String followValue = robots.getValue("follow");
          if (followValue.equalsIgnoreCase("no")) follow = false;
        }
        Vector uris = new Vector();
        // search the document for uris, 
        // store them in vector, and print them
        if (follow) searchForURIs(document.getRootElement(), uris);
    
        Enumeration e = uris.elements();
        while (e.hasMoreElements()) {
          String uri = (String) e.nextElement();
          visited.addElement(uri);
          if (index) listURIs(uri); 
        }
      
      }
    
    }
    catch (JDOMException e) {
      // couldn't load the document, 
      // probably not well-formed XML, skip it 
    }
    finally { 
      currentDepth--;
      System.out.flush();     
    }
      
  }
  
  private static Namespace xlink 
   = Namespace.getNamespace("http://www.w3.org/1999/xlink");
  
  // use recursion 
  public static void searchForURIs(Element element, Vector uris) {
    
    // look for XLinks in this element
    String uri = element.getAttributeValue("href", xlink);
    if (uri != null && !uri.equals("") 
     && !visited.contains(uri) && !uris.contains(uri)) {
      System.out.println(uri);
      uris.addElement(uri);
    }
    
    // process child elements recursively
    List children = element.getChildren();
    Iterator iterator = children.iterator();
    while (iterator.hasNext()) {
      searchForURIs((Element) iterator.next(), uris); 
    }
    
  }

  public static void main(String[] args) {
    
    if (args.length == 0) {
      System.out.println("Usage: java XLinkSpider URL1 URL2..."); 
    } 
      
    // start parsing... 
    for (int i = 0; i < args.length; i++) {
      System.err.println(args[i]); 
      listURIs(args[i]);
    } // end for
  
  } // end main

} // end XLinkSpider

Handling Namespaces

The Namespace Class

The Namespace Class

package org.jdom;

public final class Namespace {

  public static final Namespace NO_NAMESPACE = new Namespace("", "");
  public static final Namespace XML_NAMESPACE = 
   new Namespace("xml", "http://www.w3.org/XML/1998/namespace");

  // factory methods
  public static Namespace getNamespace(String prefix, String uri) {}
  public static Namespace getNamespace(String uri) {}

  // getter methods
  public String  getPrefix() {}
  public String  getURI() {}

  // utility methods
  public boolean equals(Object ob) {}
  public String  toString() {}
  public int     hashCode() {}

}

DocType Nodes

The DocType class

package org.jdom;

public class DocType implements Serializable, Cloneable {

    protected String elementName;
    protected String publicID;
    protected String systemID;

    protected DocType() {}
    public    DocType(String rootElementName, String publicID, String systemID) {}
    public    DocType(String rootElementName, String systemID) {}
    public    DocType(String rootElementName) {}

    public String  getElementName() {}
    public String  getPublicID() {}
    public DocType setPublicID(String publicID) {}
    public String  getSystemID() {}
    public DocType setSystemID(String systemID) {}

    // Usual utility methods
    public final String  toString() {}
    public final boolean equals(Object ob) {}
    public final int     hashCode() {}
    public final Object  clone() {}
    
}

Example of the DocType Class

XHTMLValidator

import java.io.*;
import org.jdom.*;
import org.jdom.input.SAXBuilder;


public class XHTMLValidator {

  public static void main(String[] args) {
    
    for (int i = 0; i < args.length; i++) {
      validate(args[i]);
    }   
    
  }

  private static SAXBuilder builder = new SAXBuilder(true);
                                                 /*  ^^^^ */
                                              /* turn on validation  */
  
  // not thread safe
  public static void validate(String source) {
        
      Document document;
      try {
        document = builder.build(source); 
      }
      catch (JDOMException e) {  
        System.out.println("Error: " + e.getMessage()); 
        e.printStackTrace();
        return; 
      }
      
      // If we get this far, then the document is valid XML.
      // Check to see whether the document is actually XHTML        
      DocType doctype = document.getDocType();
    
      if (doctype == null) {
        System.out.println("No DOCTYPE"); 
        return;
      }

      String name     = doctype.getElementName();
      String systemID = doctype.getSystemID();
      String publicID = doctype.getPublicID();
      
      if (!name.equals("html")) {
        System.out.println("Incorrect root element name " + name); 
      }
    
      if (publicID == null
       || (!publicID.equals("-//W3C//DTD XHTML 1.0 Strict//EN")
           && !publicID.equals("-//W3C//DTD XHTML 1.0 Transitional//EN")
           && !publicID.equals("-//W3C//DTD XHTML 1.0 Frameset//EN"))) {
        System.out.println(source + " does not seem to use an XHTML 1.0 DTD");
      }
    
      // Check the namespace on the root element
      Element root = document.getRootElement();
      Namespace namespace = root.getNamespace();
      String prefix = namespace.getPrefix();
      String uri = namespace.getURI();
      if (!uri.equals("http://www.w3.org/1999/xhtml")) {
        System.out.println(source 
         + " does not properly declare the"
         + " http://www.w3.org/1999/xhtml namespace"
         + " on the root element");        
      }
      if (!prefix.equals("")) {
        System.out.println(source 
         + " does not use the empty prefix for XHTML");        
      }
    
  }

}

Using the XHTMLValidator

% java XHTMLValidator http://www.w3.org/TR/xhtml1
Error: File "http://www.w3.org/TR/DTD/xhtml1-strict.dtd" not found.: Error on 
line -1 of XML document: File "http://www.w3.org/TR/DTD/xhtml1-strict.dtd" not 
found.
org.jdom.JDOMException: File "http://www.w3.org/TR/DTD/xhtml1-strict.dtd" not 
found.: Error on line -1 of XML document: File 
"http://www.w3.org/TR/DTD/xhtml1-strict.dtd" not found.
        at org.jdom.input.SAXBuilder.build(SAXBuilder.java:227)
        at org.jdom.input.SAXBuilder.build(SAXBuilder.java:359)
        at XHTMLValidator.validate(XHTMLValidator.java:25)
        at XHTMLValidator.main(XHTMLValidator.java:11)
Root cause: org.jdom.JDOMException: Error on line -1 of XML document: File 
"http://www.w3.org/TR/DTD/xhtml1-strict.dtd" not found.
        at org.jdom.input.SAXBuilder.build(SAXBuilder.java:228)
        at org.jdom.input.SAXBuilder.build(SAXBuilder.java:359)
        at XHTMLValidator.validate(XHTMLValidator.java:25)
        at XHTMLValidator.main(XHTMLValidator.java:11)

The Verifier Class

The Verifier Class

package org.jdom;

public final class Verifier {

    public static final String checkElementName(String name) {}
    public static final String checkAttributeName(String name) {}
    public static final String checkCharacterData(String text) {}
    public static final String checkNamespacePrefix(String prefix) {}
    public static final String checkNamespaceURI(String uri) {}
    public static final String checkProcessingInstructionTarget(String target) {}
    public static final String checkCommentData(String data) {}
 
    public static boolean isXMLCharacter(char c) {}
    public static boolean isXMLNameCharacter(char c) {}
    public static boolean isXMLNameStartCharacter(char c) {}
    public static boolean isXMLLetterOrDigit(char c) {}
    public static boolean isXMLLetter(char c) {}
    public static boolean isXMLCombiningChar(char c) {}
    public static boolean isXMLExtender(char c) {}
    public static boolean isXMLDigit(char c) {}

}

JDOMException

JDOMException Class

package org.jdom;

public class JDOMException extends Exception {

    protected Throwable rootCause;

    public JDOMException() {}
    public JDOMException(String message)  {}
    public JDOMException(String message, Throwable rootCause)  {} 
       
    public String    getMessage() {}
    public void      printStackTrace() {}
    public void      printStackTrace(PrintStream s) {}
    public void      printStackTrace(PrintWriter w) {}
    public Throwable getRootCause()  {}

}

The org.jdom.output Package

Serialization

XMLOutputter

package org.jdom.output;

public class XMLOutputter implements Cloneable {

    protected static final String STANDARD_INDENT = "  ";
    
    public XMLOutputter() {}
    public XMLOutputter(String indent) {}
    public XMLOutputter(String indent, boolean newlines) {}
    public XMLOutputter(String indent, boolean newlines, String encoding) {}
    public XMLOutputter(XMLOutputter that) {}
    
    public void setLineSeparator(String separator) {}
    public void setNewlines(boolean newlines) {}
    public void setEncoding(String encoding) {}
    public void setOmitEncoding(boolean omitEncoding) {}
    public void setSuppressDeclaration(boolean suppressDeclaration) {}
    public void setExpandEmptyElements(boolean expandEmptyElements) {}
    public void setTrimText(boolean trimText) {}
    public void setPadText(boolean padText) {}
    public void setIndent(String indent) {}
    public void setIndent(boolean doIndent) {}
    public void setIndentLevel(int indentLevel) {}
    public void setIndentSize(int indentSize) {}

    protected void indent(Writer out, int level) throws IOException {}
    protected void maybePrintln(Writer out) throws IOException  {}
    protected Writer makeWriter(OutputStream out) 
     throws java.io.UnsupportedEncodingException {}
    protected Writer makeWriter(OutputStream out, String encoding) 
     throws java.io.UnsupportedEncodingException {}
     
    public void output(Document doc, OutputStream out) throws IOException {}
    public void output(Document doc, Writer writer) throws IOException {}
    public void output(Element element, Writer out) throws IOException {}
    public void output(Element element, OutputStream out) {}
    public void outputElementContent(Element element, Writer out) throws IOException {}
    public void output(CDATA cdata, Writer out) throws IOException {}
    public void output(CDATA cdata, OutputStream out) throws IOException {}
    public void output(Comment comment, Writer out) throws IOException {}
    public void output(Comment comment, OutputStream out) throws IOException {}
    public void output(String string, Writer out) throws IOException {}
    public void output(String string, OutputStream out) throws IOException {}
    public void output(Entity entity, Writer out) throws IOException {}
    public void output(Entity entity, OutputStream out) throws IOException {}
    public void output(ProcessingInstruction processingInstruction, Writer out)
      throws IOException {}
    public void output(ProcessingInstruction processingInstruction, OutputStream out)
     throws IOException {}
    public String outputString(Document doc) throws IOException {}
    public String outputString(Element element) throws IOException {}

    // internal printing methods
    protected void printDeclaration(Document doc, Writer out, String encoding) 
     throws IOException {}    
    protected void printDocType(DocType docType, Writer out) throws IOException {}
    protected void printComment(Comment comment, Writer out, int indentLevel) 
     throws IOException {}
    protected void printProcessingInstruction(ProcessingInstruction pi,
     Writer out, int indentLevel) throws IOException {}
    protected void printCDATASection(CDATA cdata, Writer out, int indentLevel) 
     throws IOException {}
    protected void printElement(Element element, Writer out,
     int indentLevel, NamespaceStack namespaces) throws IOException {}
    protected void printElementContent(Element element, Writer out,
     int indentLevel, NamespaceStack namespaces, List mixedContent) 
     throws IOException {}
    protected void printString(String s, Writer out) throws IOException {}
    protected void printEntity(Entity entity, Writer out) throws IOException {}
    protected void printNamespace(Namespace ns, Writer out) throws IOException {}
    protected void printAttributes(List attributes, Element parent, 
     Writer out, NamespaceStack namespaces)  
     throws IOException {}
    
    public int parseArgs(String[] args, int i) {} 
    
}

Using the XMLOutputter Class Directly

Using the XMLOutputter Class Indirectly

JDOM based TagStripper

A bug in the current version of JDOM prevents this from working.

import org.jdom.*;
import org.jdom.output.XMLOutputter;
import org.jdom.input.SAXBuilder;
import java.io.*;
import java.util.*;


public class TagStripper extends XMLOutputter {

  public TagStripper() {
    super();
  }

  // Things we won't print at all
  protected void printDeclaration(Document doc, Writer out, String encoding) {}
  protected void printComment(Comment comment, Writer out, int indentLevel) {}
  protected void printDocType(DocType docType, Writer out) {}
  protected void printProcessingInstruction(ProcessingInstruction pi, 
   Writer out, int indentLevel) {}
  protected void printNamespace(Namespace ns, Writer out) {}
  protected void printAttributes(List attributes, Writer out) {}
  
  protected void printElement(Element element, Writer out, 
   int indentLevel, NamespaceStack namespaces) throws IOException {
    
    List content = element.getMixedContent();
    Iterator iterator = content.iterator();
    while (iterator.hasNext()) {
      Object o = iterator.next();
      if (o instanceof String) {
        out.write((String) o);
        this.maybePrintln(out);
      }
      else if (o instanceof Element) {
        printElement((Element) o, out, indentLevel, namespaces);
      }
    }
          
  }

  // Could easily have put main() method in a separate class
  public static void main(String[] args) {
     
    if (args.length == 0) {
      System.out.println(
       "Usage: java TagStripper URL1 URL2..."); 
    } 
      
    TagStripper stripper = new TagStripper();
    SAXBuilder builder   = new SAXBuilder();
    
    // start parsing... 
    for (int i = 0; i < args.length; i++) {
      
      // command line should offer URIs or file names
      try {
        Document doc = builder.build(args[i]);
        stripper.output(doc, System.out);
      }
      catch (JDOMException e) { // a well-formedness error
        System.out.println(args[i] + " is not well formed.");
        System.out.println(e.getMessage());
      }
      catch (IOException e) { // a well-formedness error
        System.out.println(e.getMessage());
      }
      
    }  
  
  }

}

Output from a JDOM based TagStripper

% java TagStripper hotcop.xml
Hot Cop
Jacques Morali
Henri Belolo
Victor Willis
Jacques Morali
A & M Records
6:20
1978
Village People

Talking to DOM Programs

Talking to SAX Programs

What JDOM doesn't do

To Learn More


Questions?

Part VI: XML Base and XInclude

The problem is that we're not providing the tools. We're providing the specs. That's a whole different ball game. If tools existed for actually making really interesting use of RDF and XLink and XInclude then people would use them. If IE and/or Mozilla supported the full gamut of specs, from XSLT 1.0 to XLink and XInclude (OK, so they're not quite REC's, but with time...) then you would find people using them more.
--Matt Sergeant on the xml-dev mailing list

What is XML Base?

The xml:base attribute

<slide xml:base="http://www.ibiblio.org/xml/slides/xmldevcon2000sanjose/advancedxml">
  <title>The xml:base attribute</title>
  ...
  <previous xlink:type="simple" xlink:href="What_Is_XBase.xml"/>
  <next xlink:type="simple" xlink:href="xbaseexample.xml"/>
</slide>

XML Base Example

Adapted from the XML Base spec:

<?xml version="1.0"?>
<doc xml:base="http://example.org/today/"
     xmlns:xlink="http://www.w3.org/1999/xlink">
  <head>
    <title>Virtual Library</title>
  </head>
  <body>
    <paragraph>
      See <link xlink:type="simple" xlink:href="new.xml">what's
      new</link>!</paragraph>
    <paragraph>Check out the hot picks of the day!</paragraph>
    <olist xml:base="/hotpicks/">
      <item>
        <link xlink:type="simple" xlink:href="pick1.xml">Hot Pick #1</link>
      </item>
      <item>
        <link xlink:type="simple" xlink:href="pick2.xml">Hot Pick #2</link>
      </item>
      <item>
        <link xlink:type="simple" xlink:href="pick3.xml">Hot Pick #3</link>
      </item>
    </olist>
  </body>
</doc>

Open Issues

What is XInclude?

Alternatives (and why they don't work)

The include element

<book xmlns:xinclude="http://www.w3.org/1999/XML/xinclude">
  <title>Processing XML with Java</title>
  <chapter><xinclude:include href="dom.xml"/></chapter>
  <chapter><xinclude:include href="sax.xml"/></chapter>
  <chapter><xinclude:include href="jdom.xml"/></chapter>
</book>

The parse attribute

parse="xml"
The resource must be parsed as XML and the infosets merged. This is the default.
parse="text"
The resource must be treated as pure text and inserted as a text node. When serialized, this means that characters like < will change to &lt; and so forth. 
<slide xmlns:xinclude="http://www.w3.org/1999/XML/xinclude">
  <title>The href attribute</title>
  
<ul>
  <li>Identifies the document to be included with a URI</li>
  <li>The document at the URI replaces the <code>include</code> 
      element in the including document</li>
  <li>The <code>xinclude</code> prefix is bound to the http://www.w3.org/1999/XML/xinclude
  namespace URI. 
  </li>
</ul>  

<pre><code><xinclude:include parse="text" href="processing_xml_with_java.xml"/>
</code></pre>
        
  <description>
      A slide from Elliotte Rusty Harold's Processing XML with Java course at
      <host_ref/>, <date_ref/>
    </description>
  <last_modified>October 26, 2000</last_modified>
</slide>

Implementation as a SAX filter

Implementation as JDOM 

/*--

 Copyright 2000 Elliotte Rusty Harold.
 All rights reserved.

 I haven't yet decided on a license.
 It will be some form of open source.

 THIS SOFTWARE IS PROVIDED "AS IS" AND ANY EXPRESSED OR IMPLIED
 WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
 DISCLAIMED.  IN NO EVENT SHALL THE APACHE SOFTWARE FOUNDATION OR
 ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
 LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
 USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
 ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
 OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
 OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 SUCH DAMAGE.

 */

package com.macfaq.xml;

import java.net.URL;
import java.net.MalformedURLException;
import java.util.Stack;
import java.util.Iterator;
import java.util.List;
import java.io.File;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.BufferedInputStream;
import java.io.InputStream;
import org.jdom.Namespace;
import org.jdom.Comment;
import org.jdom.CDATA;
import org.jdom.JDOMException;
import org.jdom.Attribute;
import org.jdom.Element;
import org.jdom.ProcessingInstruction;
import org.jdom.Document;
import org.jdom.input.SAXBuilder;
import org.jdom.output.XMLOutputter;

/**
 * <p><code>XIncluder</code> provides methods to
 * resolve JDOM elements and documents to produce
 * a new Document or Element with all
 * XInclude references resolved.
 * </p>
 *
 *
 * @author Elliotte Rusty Harold
 * @version 1.0d2
 */
public class XIncluder {

  public final static Namespace XINCLUDE_NAMESPACE
    = Namespace.getNamespace("xinclude", "http://www.w3.org/1999/XML/xinclude");

  // No instances allowed
  private XIncluder() {}

  private static SAXBuilder builder = new SAXBuilder();

  /**
    * <p>
    * This method resolves a JDOM <code>Document</code>
    * and merges in all XInclude references.
    * If a referenced document cannot be found it is replaced with
    * an error message. The Document object returned is a new document.
    * The original <code>Document</code> is not changed.
    * </p>
    *
    * @param original <code>Document</code> that will be processed
    * @param base     <code>String</code> form of the base URI against which
    *                 relative URLs will be resolved. This can be null if the
    *                 document includes an <code>xml:base</code> attribute.
    * @return Document new <code>Document</code> object in which all
    *                  XInclude elements have been replaced.
    * @throws CircularIncludeException if this document possesses a cycle of
    *                                  XIncludes.
    * @throws MalformedURLException if Java cannot parse the base URI using the
    *                               the normal methods of java.net.URL.
    */
    public static Document resolve(Document original, String base)
      throws CircularIncludeException, MalformedURLException {

        if (original == null) throw new NullPointerException("Document must not be null");
  
        Element root = original.getRootElement();
        Element resolved = (Element) resolve(root, base);
  
        // catch a ClassCastException if a String is returned????
        // Is the root element allowed to be replaced by
        // an parse="text"
    
        Document result = new Document(resolved, original.getDocType());
    
        Iterator iterator = original.getMixedContent().iterator();
        while (iterator.hasNext()) {
          Object o = iterator.next();
          if (o instanceof Comment) {
            Comment c = (Comment) o;
            result.addContent((Comment) c.clone());
          }
          else if (o instanceof ProcessingInstruction) {
            ProcessingInstruction pi =(ProcessingInstruction) o;
            result.addContent((ProcessingInstruction) pi.clone());
          }
        }
    
        return result;
  }

  /**
    * <p>
    * This method resolves a JDOM <code>Element</code>
    * and merges in all XInclude references. This process is recursive.
    * The element returned contains no XInclude elements.
    * If a referenced document cannot be found it is replaced with
    * an error message. The <code>Element</code> object returned is a new element.
    * The original <code>Element</code> is not changed.
    * </p>
    *
    * @param original <code>Element</code> that will be processed
    * @param base     <code>String</code> form of the base URI against which
    *                 relative URLs will be resolved. This can be null if the
    *                 element includes an <code>xml:base</code> attribute.
    * @return Object  Either an <code>Element</code>
    *                 (<code>parse="text"</code>) or a <code>String</code>
    *                 (<code>parse="xml"</code>)
    * @throws CircularIncludeException if this <code>Element</code> contains an XInclude element
    *                                  that attempts to include a document in which 
    *                                  this element is directly or indirectly included.
    */
    public static Object resolve(Element original, String base)
     throws CircularIncludeException, MalformedURLException {

        if (original == null) {
          throw new NullPointerException("You can't XInclude a null element.");
        }
        Stack bases = new Stack();
        if (base != null) bases.push(base);
    
        Object result = resolve(original, bases);
        bases.pop();
        return result;

    }

    private static boolean isIncludeElement(Element element) {
        
        if (element.getName().equals("include") &&
            element.getNamespace().equals(XINCLUDE_NAMESPACE)) {
          return true;
        }
        return false;
        
    }


  /**
    * <p>
    * This method resolves a JDOM <code>Element</code>
    * and merges in all XInclude references. This process is recursive.
    * The element returned contains no XInclude elements.
    * If a referenced document cannot be found it is replaced with
    * an error message. The <code>Element</code> object returned is a new element.
    * The original <code>Element</code> is not changed.
    * </p>
    *
    * @param original <code>Element</code> that will be processed
    * @param bases    <code>Stack</code> containing the string forms of
    *                 all the URIs of doucments which contain this element
    *                 thorugh XIncludes. This used to detect if a circular 
    *                 reference is being used. 
    * @return Object  Either an <code>Element</code>
    *                 (<code>parse="text"</code>) or a <code>String</code>
    *                 (<code>parse="xml"</code>)
    * @throws CircularIncludeException if this <code>Element</code> contains an XInclude element
    *                                  that attempts to include a document in which 
    *                                  this element is directly or indirectly included.
    */
  protected static Object resolve(Element original, Stack bases)
   throws CircularIncludeException {

    Element result;
    String base = "";
    if (bases.size() != 0) base = (String) bases.peek();

    if (isIncludeElement(original)) {
      Attribute href = original.getAttribute("href");
      if (href == null) { // illegal, what kind of exception????
        throw new IllegalArgumentException("Missing href attribute");
      }
      Attribute baseAttribute
       = original.getAttribute("base", Namespace.XML_NAMESPACE);
      if (baseAttribute != null) base = baseAttribute.getValue();
      boolean parse = true;
      Attribute parseAttribute = original.getAttribute("parse");
      if (parseAttribute != null) {
        if (parseAttribute.getValue().equals("text")) parse = false;
      }

      URL remote;
      if (base != null) {
        try {
          URL context = new URL(base);
          remote = new URL(context, href.getValue());
        }
        catch (MalformedURLException ex) {
          return "Unresolvable URL " + base + "/" + href.getValue();
        }
      }
      else {
        try {
          remote = new URL(href.getValue());
        }
        catch (MalformedURLException ex) {
          return "Unresolvable URL " + href.getValue();
        }
      }

      if (parse) {
                 // checks for equality (OK) or identity (not OK)????
        if (bases.contains(remote.toExternalForm())) {
          // need to figure out how to get file and number where
          // bad include occurs
          throw new CircularIncludeException(
            "Circular XInclude Reference to "
           + remote.toExternalForm() + " in " );
        }

        try {
          Document doc = builder.build(remote);
          bases.push(remote.toExternalForm());
          result = (Element) resolve(doc.getRootElement(), bases);
          bases.pop();
        }
        // Make this configurable
        catch (JDOMException e) {
           return "Document not found: " + remote.toExternalForm()
            + "\r\n" + e.getMessage();
        }
      }
      else { // insert text
        return downloadTextDocument(remote);
      }

    }
    // not an include element
    else { // recursively process children
       result = new Element(original.getName(), original.getNamespace());
       Iterator attributes = original.getAttributes().iterator();
       while (attributes.hasNext()) {
         Attribute a = (Attribute) attributes.next();
         result.addAttribute((Attribute) a.clone());
       }
       List children = original.getMixedContent();

       Iterator iterator = children.iterator();
       while (iterator.hasNext()) {
         Object o = iterator.next();
         if (o instanceof Element) {
           Element e = (Element) o;
           Object resolved = resolve(e, bases);
           if (resolved instanceof String) {
               result.addContent((String) resolved);
           }
           else result.addContent((Element) resolved);
         }
         else if (o instanceof String) {
           result.addContent((String) o);
         }
         else if (o instanceof Comment) {
           result.addContent((Comment) o);
         }
         else if (o instanceof CDATA) {
           result.addContent((CDATA) o);
         }
         else if (o instanceof ProcessingInstruction) {
           result.addContent((ProcessingInstruction) o);
         }
       }
    }

    return result;

  }

  /**
    * <p>
    * This utility method reads a document at a specified URL
    * and returns the contents of that document as a <code>String</code>.
    * It's used to include files with <code>parse="text"</code>
    * </p>
    *
    * <p>
    * If the document cannot be located due to an IOException,
    * then an error message string is returned. I'm not yet convinced this 
    * is the right behavior. Perhaps I should pass on the exception?
    * </p>
    *
    * @param source   <code>URL</code> of the doucment that will be stored in 
    *                 <code>String</code>. 
    * @return String  The document retrieved from the source <code>URL</code>
    *                 or an error message if the document can't be retrieved.
    *                 Note: throwing an exception might be better here. I should
    *                 at least allow the setting of the eror message.
    */    
    public static String downloadTextDocument(URL source) {
          
        StringBuffer s = new StringBuffer();
        try {
          InputStream in = new BufferedInputStream(source.openStream());
          // does XInclude give you anything to specify the character set????
          InputStreamReader reader = new InputStreamReader(in, "8859_1");
          int c;
          while ((c = in.read()) != -1) {
            if (c == '<') s.append("&lt;");
            else if (c == '&') s.append("&amp;");
            else s.append((char) c);
          }
          return s.toString();
        }
        catch (IOException e) {
          return "Document not found: " + source.toExternalForm();
        }
      
    }

    /**
      * <p>
      * The driver method for the XIncluder program.
      * I'll probably move this to a separate class soon.
      * </p>
      *
      * @param args  <code>args[0]</code> contains the URL or file name 
      *              of the document to be procesed. 
      */
    public static void main(String[] args) {
  
        SAXBuilder builder = new SAXBuilder();
        XMLOutputter outputter = new XMLOutputter();
        for (int i = 0; i < args.length; i++) {
          try {
            Document input = builder.build(args[i]);
            // absolutize URL
            String base = args[i];
            if (base.indexOf(':') < 0) {
              File f = new File(base);
              base = f.toURL().toExternalForm();
            }
            Document output = resolve(input, base);
            // need to set encoding on this to Latin-1 and check what
            // happens to UTF-8 curly quotes
            outputter.output(output, System.out);
          }
          catch (Exception e) {
            System.err.println(e);
            e.printStackTrace();
          }
        }
  
    }

}

Implementation as DOM

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Index | Cafe con Leche
Copyright 2000 Elliotte Rusty Harold
elharo@metalab.unc.edu
Last Modified December 5, 2000