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Xerces2 is the next generation of high performance, fully compliant XML parsers in the Apache Xerces family. This new version of Xerces introduces the Xerces Native Interface (XNI), a complete framework for building parser components and configurations that is extremely modular and easy to program. The Apache Xerces2 parser is the reference implementation of XNI but other parser components, configurations, and parsers can be written using the Xerces Native Interface. For complete design and implementation documents, refer to the XNI Manual. Xerces2 is a fully conforming XML Schema 1.0 processor. A partial experimental implementation of the XML Schema 1.1 Structures and Datatypes Working Drafts (December 2009) and an experimental implementation of the XML Schema Definition Language (XSD): Component Designators (SCD) Candidate Recommendation (January 2010) are provided for evaluation. For more information, refer to the XML Schema page. Xerces2 also provides a complete implementation of the Document Object Model Level 3 Core and Load/Save W3C Recommendations and provides a complete implementation of the XML Inclusions (XInclude) W3C Recommendation. It also provides support for OASIS XML Catalogs v1.1. Xerces2 is able to parse documents written according to the XML 1.1 Recommendation, except that it does not yet provide an option to enable normalization checking as described in section 2.13 of this specification. It also handles namespaces according to the XML Namespaces 1.1 Recommendation, and will correctly serialize XML 1.1 documents if the DOM level 3 load/save APIs are in use.

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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 226184 2005-04-08 10:53:24Z neeraj $

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.
 *
 * 
 * This module, both source code and documentation, is in the
 * Public Domain, and comes with NO WARRANTY.
 * See http://www.saxproject.org
 * for further information.
 * 
 *
 * 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:
 *
 * 
 * {@link org.xml.sax.EntityResolver EntityResolver}
 * {@link org.xml.sax.DTDHandler DTDHandler}
 * {@link org.xml.sax.ContentHandler ContentHandler}
 * {@link org.xml.sax.ErrorHandler ErrorHandler}
 * 
 *
 * 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.
 *
 * This class replaces the deprecated SAX1
 * {@link org.xml.sax.HandlerBase HandlerBase} class.
 *
 * @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.
     *
     * 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.
     *
     * @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.
     *
     * 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.
     *
     * @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.
     *
     * By default, do nothing.  Application writers may override this
     * method in a subclass to keep track of the unparsed entities
     * declared in a document.
     *
     * @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.
     *
     * 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.
     *
     * @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.
     *
     * 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).
     *
     * @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.
     *
     * 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).
     *
     * @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.
     *
     * 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).
     *
     * @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.
     *
     * By default, do nothing.  Application writers may override this
     * method in a subclass to take specific actions at the end of
     * each prefix mapping.
     *
     * @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.
     *
     * 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).
     *
     * @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.
     *
     * 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).
     *
     * @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.
     *
     * 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).
     *
     * @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.
     *
     * 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).
     *
     * @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.
     *
     * 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.
     *
     * @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.
     *
     * 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.
     *
     * @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.
     *
     * 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.
     *
     * @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.
     *
     * 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.
     *
     * @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.
     *
     * 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.
     *
     * @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