Ivor Horton's Beginning Java™ 2, JDK™ 5th Edition

23.1. The Document Object Model (DOM)

As you saw in the previous chapter, a DOM parser presents you with an object encapsulating the entire XML structure. You can then call methods belonging to this object to navigate through the document tree and process the elements and attributes in the document in whatever way you want. This is quite different to SAX as I've already noted, but nonetheless there is quite a close relationship between DOM and SAX.

The mechanism for getting access to a DOM parser is very similar to what you used to obtain a SAX parser. You start with a factory object that you obtain like this:

DocumentBuilderFactory builderFactory = DocumentBuilderFactory.newInstance();

The newInstance() method is a static method in the javax.xml.parsers.DocumentBuilderFactory class for creating factory objects. As with SAX, this approach of dynamically creating a factory object that you then use to create a parser allows you to change the parser you are using without modifying or recompiling your code. You use the factory object to create a javax.xml.parsers.DocumentBuilder object that encapsulates a DOM parser:

DocumentBuilder builder = null;
try {
  builder = builderFactory.newDocumentBuilder();
} catch(ParserConfigurationException e) {
  e.printStackTrace();
}

As you'll see, when a DOM parser reads an XML document, it makes it available in its entirety as an object of type Document. The name of the class that encapsulates a DOM parser has obviously been chosen to indicate that ...