DOMBrowser.java - DOM Interface Java Example

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∟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 1.8.

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) 2002-2018 HerongYang.com. All Rights Reserved.
 */
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"?>
<p>Hello world!</p>

You will get the following output with JDK 10 and 1.8:

herong> java DOMBrowser hello.xml

#document: 9, 1, -1, null
 p: 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 "p", of type 1, has 1 child node, 0 attribute, and no value.
The third line in the output says that there is child node nested inside the "p" node. The child node is called "#text", of type 3, has 0 child node. It has no attribute. But it has a value of string "Hello world!".
Note that the text enclosed by the "p tag is parsed into a node separated from the "body" node.