DOM

DOM

Elliotte Rusty Harold

Software Development 2002 East

Thursday, November 21, 2002

elharo@metalab.unc.edu

http://www.cafeconleche.org/

Where we're going

Relevant Standards

DOM Requirements

Prerequisites

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://www.cafeconleche.org/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.cafeconleche.org/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 -->

Elements vs. Entities

Parsed Character Data

Questions?

DOM, The Document Object Model

The DOM (like XML) is not a triumph of elegance; it's a triumph of "if we do not hang together, we shall hang separately." At least the Browser Wars were not followed by API Wars. Better a common API that we all love to hate than a bazillion contending APIs that carve the Web up into contending enclaves of True Believers.

--Mike Champion on the xml-dev mailing list, September 27, 2001

Trees

Document Object Model

DOM Evolution

DOM Implementations for Java

Eight Modules:

Which modules and features are supported?

Which modules are supported?

import org.apache.xerces.dom.DOMImplementationImpl;
import org.w3c.dom.*;
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 JAXP Process

  1. javax.xml.parsers.DocumentBuilderFactory.newInstance() creates a DocumentBuilderFactory

  2. The factory's newBuilder() method creates a DocumentBuilder

  3. The builder parses the document and returns a DOM org.w3c.dom.Document object.

  4. The entire document is stored in memory.

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

Parsing documents with a JAXP DocumentBuilder 

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

public class JAXPParserMaker {

  public static void main(String[] args) {
     
    try {       
      DocumentBuilderFactory builderFactory 
       = DocumentBuilderFactory.newInstance();
      DocumentBuilder parser 
       = builderFactory.newDocumentBuilder();
    
      for (int i = 0; i < args.length; i++) {
        try {
          // Read the entire document into memory
          Document d = parser.parse(args[i]); 
          // work with the document...
        }
        catch (SAXException e) {
        System.err.println(e); 
        }
        catch (IOException e) {
          System.err.println(e); 
        }
      
      } // end for
      
    }
    catch (ParserConfigurationException e) {
      System.err.println("You need to install a JAXP aware parser.");
    }
   
  }

}

Questions?

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...

Questions?

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.getNodeType() == Node.ELEMENT_NODE) {
      
      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"?><!-- This should be a four digit year like "1999",
     not a two-digit year like "99" --><SONG xmlns="http://www.cafeconleche.org/namespace/song" ID="_1" 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" xmlns:xlink="http://www.w3.org/1999/xlink" 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" xmlns:xlink="http://www.w3.org/1999/xlink" 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.getNodeType() == Node.TEXT_NODE
     || node.getNodeType() == Node.COMMENT_NODE
     || node.getNodeType() == Node.CDATA_SECTION_NODE) {
      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 support 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 support 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 children. 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 Xerces/DOM program that writes Fibonacci numbers into an XML document

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


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.ONE;
      BigInteger high = BigInteger.ONE;

      Element root = fibonacci.getDocumentElement();

      for (int i = 1; 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();
    }

  }

}

A JAXP/DOM program that writes Fibonacci numbers into an XML document

import java.math.BigInteger;
import java.io.*;
import org.w3c.dom.*;
import javax.xml.parsers.*;


public class FibonacciJAXP {

  public static void main(String[] args) {

    try {       
      DocumentBuilderFactory factory 
       = DocumentBuilderFactory.newInstance();
      DocumentBuilder builder = factory.newDocumentBuilder();
      DOMImplementation impl = builder.getDOMImplementation();

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

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

      Element root = fibonacci.getDocumentElement();

      for (int i = 1; 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();
    }
    catch (ParserConfigurationException e) {
      System.err.println("You need to install a JAXP aware DOM implementation.");
    }
    
  }

}

Serialization

A DOM program that writes Fibonacci numbers onto System.out

import java.math.BigInteger;
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.ONE;
      BigInteger high = BigInteger.ONE;      
      
      Element root = fibonacci.getDocumentElement(); 

      for (int i = 1; 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="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="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.setIndenting(true);
        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

<?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>Scripting News</name>
    <url>http://www.scripting.com/</url>
    <ownerName>Dave Winer</ownerName>
    <ownerEmail>dave@userland.com</ownerEmail>
    <description>News and commentary from the cross-platform scripting community.</description>
    <imageUrl>http://www.scripting.com/gifs/tinyScriptingNews.gif</imageUrl>
    <adImageUrl>http://static.userland.com/weblogMonitor/ads/dave@userland.com.gif</adImageUrl>
  </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>

The point is this:

Questions?

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Index | Cafe con Leche
Copyright 2000-2002 Elliotte Rusty Harold
elharo@metalab.unc.edu
Last Modified November 26, 2002