DOMBrowser.java - DOM Interface Java Example

XML Tutorials - Herong's Tutorial Notes

Dr. Herong Yang, Version 4.00

∟DOM (Document Object Model) Programming Interface

∟DOMBrowser.java - DOM Interface Java Example

This section provides a tutorial example on how to parse an XML file and print it back in a tree format using DOM interface in Java - JDK 1.4.1.

The following Java program illustrates how an XML file can be parsed into a DOM document tree, and how get methods of Node interface can be used to browse the tree:

/**
 * DOMBrowser.java
 * Copyright (c) 2002 by Dr. Herong Yang. http://www.herongyang.com/
 */
import java.io.*;
import javax.xml.parsers.*;
import org.w3c.dom.*;
import org.xml.sax.*;
class DOMBrowser {
   public static void main(String[] args) {
      try {
         File x = new File(args[0]);
         DocumentBuilderFactory f
            = DocumentBuilderFactory.newInstance();
         DocumentBuilder b = f.newDocumentBuilder();
         Document d = b.parse(x);
         printNode(d, "");
      } catch (ParserConfigurationException e) {
         System.out.println(e.toString());      
      } catch (SAXException e) {
         System.out.println(e.toString());      
      } catch (IOException e) {
         System.out.println(e.toString());      
      }
   }
   static void printNode(Node n, String p) {
      NodeList l = n.getChildNodes();
      NamedNodeMap m = n.getAttributes();
      int ml = -1;
      if (m!=null) ml = m.getLength(); 
      System.out.println(p+n.getNodeName()+": "+n.getNodeType()+", "
         +l.getLength()+", "+ml+", "+n.getNodeValue());
      for (int i=0; i<ml; i++) {
         Node c = m.item(i);
         printNode(c,p+" |-");
      }
      for (int i=0; i<l.getLength(); i++) {
         Node c = l.item(i);
         printNode(c,p+" ");
      }
   }
}

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

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

You will get the following output:

C:\herong\xml>java DOMBrowser hello.xml 

#document: 9, 1, -1, null
 body: 1, 1, 0, null
  #text: 3, 0, -1, Hello world!

Here is how to read the output:

The Document object is also a Node object, which is presented by the first line in the output.
The "xml" processing instruction is not part of the document object.
The second line in the output says that the root element is named as "body", of type 1, has 1 child node, has 0 attribute, and has no value.
The third line in the output says that there is child node nested inside the "body" node. The child node is called "#text", of type 3, has 0 child node, could not have any attribute, and has a value of string "Hello world!".
Note that the text enclosed by the "body" tags is parsed into a node separated from the "body" node.

Notes and sample codes in this section are based on JDK 1.4.1_01.

Table of Contents

About This Book

Introduction of XML (eXtensible Markup Language)

XML File Syntax

XML File Browsers

►DOM (Document Object Model) Programming Interface

What Is DOM (Document Object Model)?

Using DOM Implementation Provided in JDK 1.4

DOM Specifications and DOM Node Interface

►DOMBrowser.java - DOM Interface Java Example

XML DOM Node Tree Example