Today's tip continues our discussion of parsing XML with Java using the JAXP parser from Sun. As discussed, JAXP supports both DOM and SAX. Today, we'll take a look at DOM.

As with any Java application, you start by importing the necessary packages:

		import org.w3c.dom.*; 
       import javax.xml.parsers.DocumentBuilderFactory; 
       import javax.xml.parsers.DocumentBuilder; 
       import org.xml.sax.SAXException; 
       import org.xml.sax.SAXParseException; 

Unlike the SAX API, with DOM you do not have to use a URI to specify the file to parse. Instead, you simply create an instance of the File class and pass the filename to the constructor. For example, the following code creates a file using a fictitious XML file located at /usr/john/test.xml:

       File f = new File("/usr/john/test.xml"); 

Now, you're ready to start DOM'ing, which goes like this:

       // get instance of document builder factory 
       DocumentBuilderFactory dbf = 
       
       DocumentBuilderFactory.newInstance(); 
       // get instance of document builder from the factory 
       DocumentBuilder db = 
       
       docBuilderFactory.newDocumentBuilder(); 
       // parser the document 
       doc = db.parse (f); 
       doc.getDocumentElement ().normalize (); 

Voila! Hopefully, you've noticed that the boilerplate code for parsing a document with either DOM or SAX is quite similar and rather simple. You have only to retrieve an instance of a factory class and use that to create a parser. Of course, things are seldom as simple as they first appear... and in the next tip, we'll take a look at how to do more complex stuff with the document once it has been parsed.