Java in a Nutshell, 5th Edition

Name

DefaultHandler

Synopsis

This helper class implements the four commonly-used SAX handler interfaces from the org.xml.sax package and defines stub implementations for all of their methods. It is usually easier to subclass DefaultHandler and override the desired methods than it is to implement all of the interfaces (and all of their methods) from scratch. DefaultHandler implements ContentHandler, ErrorHandler, EntityResolver and DTDHandler, so you can pass an instance of this class, (or of a subclass you define) to the setContentHandler( ), setErrorHandler( ), setEntityResolver( ), and setDTDHandler( ) methods of an XMLReader. You can also pass an instance of a DefaultHandler subclass directly to one of the parse( ) methods of a javax.xml.parsers.SAXParser. The SAXParser will take care of calling the four relevant methods of its internal XMLReader.

All but two of the methods of DefaultHandler have empty bodies and do nothing. The exceptions are resolveEntity( ) which simply returns null to tell the parser to resolve the entity itself, and fatalError( ) which throws the SAXParseException object that is passed to it.

Figure 22-15. org.xml.sax.helpers.DefaultHandler

public class DefaultHandler implements org.xml.sax.ContentHandler, 
        org.xml.sax.DTDHandler, org.xml.sax.EntityResolver, 
        org.xml.sax.ErrorHandler {
// Public Constructors
     public DefaultHandler( );  
// Methods Implementing ContentHandler ...