DOMParser.java - Parsing XML Files with DOM

JDK Tutorials - Herong's Tutorial Examples

∟DOM (Document Object Model) - API for XML Files

∟DOMParser.java - Parsing XML Files with DOM

This section provides a tutorial example on how to write an XML file parser, DOMParser.java, with the org.w3c.dom.Document class included in JDK.

What is DOM (Document Object Model)? DOM is an Application Programming Interface (API) that represents an XML file as a document object, which allows application programs to manage the information contained in the document object.

Here is a program to show how different packages are used together to parse an XML file into a DOM document object:

/* DOMParser.java
 * Copyright (c) HerongYang.com. All Rights Reserved.
 */
import java.io.*;
import javax.xml.parsers.*;
import org.w3c.dom.*;
import org.xml.sax.*;
class DOMParser {
   public static void main(String[] args) {
      try {
         File x = new File(args[0]);
         DocumentBuilderFactory f
            = DocumentBuilderFactory.newInstance();
         System.out.println(f.toString());
         DocumentBuilder b = f.newDocumentBuilder();
         System.out.println(b.toString());
         Document d = b.parse(x);
         System.out.println(d.toString());
         DOMImplementation i = d.getImplementation();
         System.out.println(i.toString());
      } catch (ParserConfigurationException e) {
         System.out.println(e.toString());
      } catch (SAXException e) {
         System.out.println(e.toString());
      } catch (IOException e) {
         System.out.println(e.toString());
      }
   }
}

Now let's use this program to parse my first XML file, hello.xml:

<?xml version="1.0"?>
<body>Hello world!</body>

Output with JDK 1.8 or higher:

herong> java DOMParser.java hello.xml

com.sun.org.apache.xerces.internal.jaxp
   .DocumentBuilderFactoryImpl@1db9742

com.sun.org.apache.xerces.internal.jaxp.DocumentBuilderImpl@106d69c

[#document: null]

com.sun.org.apache.xerces.internal.dom
   .DeferredDOMImplementationImpl@52e922

Note that:

javax.xml.parsers.DocumentBuilderFactory.newInstance() method is used to create a new factory instance using a factory implementation from the com.sun.org.apache.xerces.* package.
javax.xml.parsers.DocumentBuilder.newDocumentBuilder() method is used to create a new builder instance using a builder implementation from com.sun.org.apache.xerces.* package.
javax.xml.parsers.DocumentBuilder.parse() method is used to parse the XML file into an org.w3c.dom.Document object implemented from com.sun.org.apache.xerces.* package.

If you are using JDK 1.4.1, the output should look like:

herong> \j2sdk1.4.1_01\bin\java DOMParser hello.xml

org.apache.crimson.jaxp.DocumentBuilderFactoryImpl@1c78e57
org.apache.crimson.jaxp.DocumentBuilderImpl@13e8d89
org.apache.crimson.tree.XmlDocument@1cfb549
org.apache.crimson.tree.DOMImplementationImpl@1820dda