Today's tip continues our discussion on parsing XML using Java and the SAX API. In our previous tip, I showed you some boilerplate code for creating a SAX parser and parsing a document. The interesting part of using SAX, however, is implementing the document handler. Recall that SAX is an event-based API. This means, basically, you give it an instance of a class and it calls methods of the class to handle the various items in the XML document. To implement this, the SAX API defines an interface named DocumentHandler. Here is a sample, skeleton document handler (for simplicity, it shows only a few of the more commonly used methods):

class MyDocumentHandler implements DocumentHandler 
{ 
     public void startDocument () throws SAXException 
     {	// called once, at the start of the document 
     } 
     public void endDocument () throws SAXException 
     { // called once, at the end of the document 
     } 
     public void startElement (String name, AttributeList attrs) 
     throws 
     SAXException 
     { // called when an element is encountered 
     } 
     public void endElement (String name) throws SAXException 
     { // called at the end of an element 
     } 
     public void characters (char buf [], int offset, int len) throws 
     SAXException 
     { // provides the content of elements 
     } 
}