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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 2004/12/23 22:38:42 mark 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>

     *

     * @param prefix The Namespace prefix being declared.

     * @exception org.xml.sax.SAXException Any SAX exception, possibly

     *            wrapping another exception.

     * @see org.xml.sax.ContentHandler#endPrefixMapping

     */

    public void endPrefixMapping (String prefix)

        throws SAXException

    {

        // no op

    }

    /**

     * Receive notification of the start of an element.

     *

     * <p>By default, do nothing.  Application writers may override this

     * method in a subclass to take specific actions at the start of

     * each element (such as allocating a new tree node or writing

     * output to a file).</p>

     *

     * @param uri The Namespace URI, or the empty string if the

     *        element has no Namespace URI or if Namespace

     *        processing is not being performed.

     * @param localName The local name (without prefix), or the

     *        empty string if Namespace processing is not being

     *        performed.

     * @param qName The qualified name (with prefix), or the

     *        empty string if qualified names are not available.

     * @param attributes The attributes attached to the element.  If

     *        there are no attributes, it shall be an empty

     *        Attributes object.

     * @exception org.xml.sax.SAXException Any SAX exception, possibly

     *            wrapping another exception.

     * @see org.xml.sax.ContentHandler#startElement

     */

    public void startElement (String uri, String localName,

                              String qName, Attributes attributes)

        throws SAXException

    {

        // no op

    }

    /**

     * Receive notification of the end of an element.

     *

     * <p>By default, do nothing.  Application writers may override this

     * method in a subclass to take specific actions at the end of

     * each element (such as finalising a tree node or writing

     * output to a file).</p>

     *

     * @param uri The Namespace URI, or the empty string if the

     *        element has no Namespace URI or if Namespace

     *        processing is not being performed.

     * @param localName The local name (without prefix), or the

     *        empty string if Namespace processing is not being

     *        performed.

     * @param qName The qualified name (with prefix), or the

     *        empty string if qualified names are not available.

     * @exception org.xml.sax.SAXException Any SAX exception, possibly

     *            wrapping another exception.

     * @see org.xml.sax.ContentHandler#endElement

     */

    public void endElement (String uri, String localName, String qName)

        throws SAXException

    {

        // no op

    }

    /**

     * Receive notification of character data inside an element.

     *

     * <p>By default, do nothing.  Application writers may override this

     * method to take specific actions for each chunk of character data

     * (such as adding the data to a node or buffer, or printing it to

     * a file).</p>

     *

     * @param ch The characters.

     * @param start The start position in the character array.

     * @param length The number of characters to use from the

     *               character array.

     * @exception org.xml.sax.SAXException Any SAX exception, possibly

     *            wrapping another exception.

     * @see org.xml.sax.ContentHandler#characters

     */

    public void characters (char ch[], int start, int length)

        throws SAXException

    {

        // no op

    }

    /**

     * Receive notification of ignorable whitespace in element content.

     *

     * <p>By default, do nothing.  Application writers may override this

     * method to take specific actions for each chunk of ignorable

     * whitespace (such as adding data to a node or buffer, or printing

     * it to a file).</p>

     *

     * @param ch The whitespace characters.

     * @param start The start position in the character array.

     * @param length The number of characters to use from the

     *               character array.

     * @exception org.xml.sax.SAXException Any SAX exception, possibly

     *            wrapping another exception.

     * @see org.xml.sax.ContentHandler#ignorableWhitespace

     */

    public void ignorableWhitespace (char ch[], int start, int length)

        throws SAXException

    {

        // no op

    }

    /**

     * Receive notification of a processing instruction.

     *

     * <p>By default, do nothing.  Application writers may override this

     * method in a subclass to take specific actions for each

     * processing instruction, such as setting status variables or

     * invoking other methods.</p>

     *

     * @param target The processing instruction target.

     * @param data The processing instruction data, or null if

     *             none is supplied.

     * @exception org.xml.sax.SAXException Any SAX exception, possibly

     *            wrapping another exception.

     * @see org.xml.sax.ContentHandler#processingInstruction

     */

    public void processingInstruction (String target, String data)

        throws SAXException

    {

        // no op

    }

    /**

     * Receive notification of a skipped entity.

     *

     * <p>By default, do nothing.  Application writers may override this

     * method in a subclass to take specific actions for each

     * processing instruction, such as setting status variables or

     * invoking other methods.</p>

     *

     * @param name The name of the skipped entity.

     * @exception org.xml.sax.SAXException Any SAX exception, possibly

     *            wrapping another exception.

     * @see org.xml.sax.ContentHandler#processingInstruction

     */

    public void skippedEntity (String name)

        throws SAXException

    {

        // no op

    }

    ////////////////////////////////////////////////////////////////////

    // Default implementation of the ErrorHandler interface.

    ////////////////////////////////////////////////////////////////////

    /**

     * Receive notification of a parser warning.

     *

     * <p>The default implementation does nothing.  Application writers

     * may override this method in a subclass to take specific actions

     * for each warning, such as inserting the message in a log file or

     * printing it to the console.</p>

     *

     * @param e The warning information encoded as an exception.

     * @exception org.xml.sax.SAXException Any SAX exception, possibly

     *            wrapping another exception.

     * @see org.xml.sax.ErrorHandler#warning

     * @see org.xml.sax.SAXParseException

     */

    public void warning (SAXParseException e)

        throws SAXException

    {

        // no op

    }

    /**

     * Receive notification of a recoverable parser error.

     *

     * <p>The default implementation does nothing.  Application writers

     * may override this method in a subclass to take specific actions

     * for each error, such as inserting the message in a log file or

     * printing it to the console.</p>

     *

     * @param e The warning information encoded as an exception.

     * @exception org.xml.sax.SAXException Any SAX exception, possibly

     *            wrapping another exception.

     * @see org.xml.sax.ErrorHandler#warning

     * @see org.xml.sax.SAXParseException

     */

    public void error (SAXParseException e)

        throws SAXException

    {

        // no op

    }

    /**

     * Report a fatal XML parsing error.

     *

     * <p>The default implementation throws a SAXParseException.

     * Application writers may override this method in a subclass if

     * they need to take specific actions for each fatal error (such as

     * collecting all of the errors into a single report): in any case,

     * the application must stop all regular processing when this

     * method is invoked, since the document is no longer reliable, and

     * the parser may no longer report parsing events.</p>

     *

     * @param e The error information encoded as an exception.

     * @exception org.xml.sax.SAXException Any SAX exception, possibly

     *            wrapping another exception.

     * @see org.xml.sax.ErrorHandler#fatalError

     * @see org.xml.sax.SAXParseException

     */

    public void fatalError (SAXParseException e)

        throws SAXException

    {

        throw e;

    }

}

// end of DefaultHandler.java