defaulthandler.java

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// DefaultHandler.java - default implementation of the core handlers.
// http://www.saxproject.org
// Written by David Megginson
// NO WARRANTY!  This class is in the public domain.
// $Id: DefaultHandler.java,v 1.1 2004/02/15 11:07:14 epr Exp $

package org.xml.sax.helpers;

import java.io.IOException;

import org.xml.sax.InputSource;
import org.xml.sax.Locator;
import org.xml.sax.Attributes;
import org.xml.sax.EntityResolver;
import org.xml.sax.DTDHandler;
import org.xml.sax.ContentHandler;
import org.xml.sax.ErrorHandler;
import org.xml.sax.SAXException;
import org.xml.sax.SAXParseException;


/**
 * Default base class for SAX2 event handlers.
 *
 * <blockquote>
 * <em>This module, both source code and documentation, is in the
 * Public Domain, and comes with <strong>NO WARRANTY</strong>.</em>
 * See <a href='http://www.saxproject.org'>http://www.saxproject.org</a>
 * for further information.
 * </blockquote>
 *
 * <p>This class is available as a convenience base class for SAX2
 * applications: it provides default implementations for all of the
 * callbacks in the four core SAX2 handler classes:</p>
 *
 * <ul>
 * <li>{@link org.xml.sax.EntityResolver EntityResolver}</li>
 * <li>{@link org.xml.sax.DTDHandler DTDHandler}</li>
 * <li>{@link org.xml.sax.ContentHandler ContentHandler}</li>
 * <li>{@link org.xml.sax.ErrorHandler ErrorHandler}</li>
 * </ul>
 *
 * <p>Application writers can extend this class when they need to
 * implement only part of an interface; parser writers can
 * instantiate this class to provide default handlers when the
 * application has not supplied its own.</p>
 *
 * <p>This class replaces the deprecated SAX1
 * {@link org.xml.sax.HandlerBase HandlerBase} class.</p>
 *
 * @since SAX 2.0
 * @author David Megginson,
 * @version 2.0.1 (sax2r2)
 * @see org.xml.sax.EntityResolver
 * @see org.xml.sax.DTDHandler
 * @see org.xml.sax.ContentHandler
 * @see org.xml.sax.ErrorHandler
 */
public class DefaultHandler
    implements EntityResolver, DTDHandler, ContentHandler, ErrorHandler
{
    

    ////////////////////////////////////////////////////////////////////
    // Default implementation of the EntityResolver interface.
    ////////////////////////////////////////////////////////////////////
    
    /**
     * Resolve an external entity.
     *
     * <p>Always return null, so that the parser will use the system
     * identifier provided in the XML document.  This method implements
     * the SAX default behaviour: application writers can override it
     * in a subclass to do special translations such as catalog lookups
     * or URI redirection.</p>
     *
     * @param publicId The public identifer, or null if none is
     *                 available.
     * @param systemId The system identifier provided in the XML 
     *                 document.
     * @return The new input source, or null to require the
     *         default behaviour.
     * @exception java.io.IOException If there is an error setting
     *            up the new input source.
     * @exception org.xml.sax.SAXException Any SAX exception, possibly
     *            wrapping another exception.
     * @see org.xml.sax.EntityResolver#resolveEntity
     */
    public InputSource resolveEntity (String publicId, String systemId)
	throws IOException, SAXException
    {
	return null;
    }
    
    

    ////////////////////////////////////////////////////////////////////
    // Default implementation of DTDHandler interface.
    ////////////////////////////////////////////////////////////////////
    
    
    /**
     * Receive notification of a notation declaration.
     *
     * <p>By default, do nothing.  Application writers may override this
     * method in a subclass if they wish to keep track of the notations
     * declared in a document.</p>
     *
     * @param name The notation name.
     * @param publicId The notation public identifier, or null if not
     *                 available.
     * @param systemId The notation system identifier.
     * @exception org.xml.sax.SAXException Any SAX exception, possibly
     *            wrapping another exception.
     * @see org.xml.sax.DTDHandler#notationDecl
     */
    public void notationDecl (String name, String publicId, String systemId)
	throws SAXException
    {
	// no op
    }
    
    
    /**
     * Receive notification of an unparsed entity declaration.
     *
     * <p>By default, do nothing.  Application writers may override this
     * method in a subclass to keep track of the unparsed entities
     * declared in a document.</p>
     *
     * @param name The entity name.
     * @param publicId The entity public identifier, or null if not
     *                 available.
     * @param systemId The entity system identifier.
     * @param notationName The name of the associated notation.
     * @exception org.xml.sax.SAXException Any SAX exception, possibly
     *            wrapping another exception.
     * @see org.xml.sax.DTDHandler#unparsedEntityDecl
     */
    public void unparsedEntityDecl (String name, String publicId,
				    String systemId, String notationName)
	throws SAXException
    {
	// no op
    }
    
    

    ////////////////////////////////////////////////////////////////////
    // Default implementation of ContentHandler interface.
    ////////////////////////////////////////////////////////////////////
    
    
    /**
     * Receive a Locator object for document events.
     *
     * <p>By default, do nothing.  Application writers may override this
     * method in a subclass if they wish to store the locator for use
     * with other document events.</p>
     *
     * @param locator A locator for all SAX document events.
     * @see org.xml.sax.ContentHandler#setDocumentLocator
     * @see org.xml.sax.Locator
     */
    public void setDocumentLocator (Locator locator)
    {
	// no op
    }
    
    
    /**
     * Receive notification of the beginning of the document.
     *
     * <p>By default, do nothing.  Application writers may override this
     * method in a subclass to take specific actions at the beginning
     * of a document (such as allocating the root node of a tree or
     * creating an output file).</p>
     *
     * @exception org.xml.sax.SAXException Any SAX exception, possibly
     *            wrapping another exception.
     * @see org.xml.sax.ContentHandler#startDocument
     */
    public void startDocument ()
	throws SAXException
    {
	// no op
    }
    
    
    /**
     * Receive notification of the end of the document.
     *
     * <p>By default, do nothing.  Application writers may override this
     * method in a subclass to take specific actions at the end
     * of a document (such as finalising a tree or closing an output
     * file).</p>
     *
     * @exception org.xml.sax.SAXException Any SAX exception, possibly
     *            wrapping another exception.
     * @see org.xml.sax.ContentHandler#endDocument
     */
    public void endDocument ()
	throws SAXException
    {
	// no op
    }


    /**
     * Receive notification of the start of a Namespace mapping.
     *
     * <p>By default, do nothing.  Application writers may override this
     * method in a subclass to take specific actions at the start of
     * each Namespace prefix scope (such as storing the prefix mapping).</p>
     *
     * @param prefix The Namespace prefix being declared.
     * @param uri The Namespace URI mapped to the prefix.
     * @exception org.xml.sax.SAXException Any SAX exception, possibly
     *            wrapping another exception.
     * @see org.xml.sax.ContentHandler#startPrefixMapping
     */
    public void startPrefixMapping (String prefix, String uri)
	throws SAXException
    {
	// no op
    }


    /**
     * Receive notification of the end of a Namespace mapping.
     *
     * <p>By default, do nothing.  Application writers may override this
     * method in a subclass to take specific actions at the end of
     * each prefix mapping.</p>