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 * Copyright (c) 2000, 2020, Oracle and/or its affiliates. All rights reserved.
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
 *
 * This code is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License version 2 only, as
 * published by the Free Software Foundation.  Oracle designates this
 * particular file as subject to the "Classpath" exception as provided
 * by Oracle in the LICENSE file that accompanied this code.
 *
 * This code is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
 * version 2 for more details (a copy is included in the LICENSE file that
 * accompanied this code).
 *
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 * 2 along with this work; if not, write to the Free Software Foundation,
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 *
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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 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:

EntityResolver
DTDHandler
ContentHandler
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 HandlerBase class.
Author:
David Megginson,
See Also:
EntityResolver
DTDHandler
ContentHandler
ErrorHandler
Since:
1.4, SAX 2.0/**
 * Default base class for SAX2 event handlers.
 *
 * <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 1.4, SAX 2.0
 * @author David Megginson,
 * @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
{
    
Constructs a DefaultHandler. /**
     * Constructs a {@code DefaultHandler}.
     */
    public DefaultHandler() {}

    ////////////////////////////////////////////////////////////////////
    // 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.
Params:
publicId – The public identifier, or null if none is
                available.
systemId – The system identifier provided in the XML
                document.
Throws:
IOException – If there is an error setting
           up the new input source.
SAXException – Any SAX exception, possibly
           wrapping another exception.
See Also:
EntityResolver.resolveEntity
Returns:
The new input source, or null to require the
        default behaviour./**
     * 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 identifier, 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.
     * @throws java.io.IOException If there is an error setting
     *            up the new input source.
     * @throws org.xml.sax.SAXException Any SAX exception, possibly
     *            wrapping another exception.
     * @see org.xml.sax.EntityResolver#resolveEntity
     */
    @Override
    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.
Params:
name – The notation name.
publicId – The notation public identifier, or null if not
                available.
systemId – The notation system identifier.
Throws:
SAXException – Any SAX exception, possibly
           wrapping another exception.
See Also:
DTDHandler.notationDecl/**
     * 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.
     * @throws org.xml.sax.SAXException Any SAX exception, possibly
     *            wrapping another exception.
     * @see org.xml.sax.DTDHandler#notationDecl
     */
    @Override
    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.
Params:
name – The entity name.
publicId – The entity public identifier, or null if not
                available.
systemId – The entity system identifier.
notationName – The name of the associated notation.
Throws:
SAXException – Any SAX exception, possibly
           wrapping another exception.
See Also:
DTDHandler.unparsedEntityDecl/**
     * 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.
     * @throws org.xml.sax.SAXException Any SAX exception, possibly
     *            wrapping another exception.
     * @see org.xml.sax.DTDHandler#unparsedEntityDecl
     */
    @Override
    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.
Params:
locator – A locator for all SAX document events.
See Also:
ContentHandler.setDocumentLocator
Locator/**
     * 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
     */
    @Override
    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).
Throws:
SAXException – Any SAX exception, possibly
           wrapping another exception.
See Also:
ContentHandler.startDocument/**
     * 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>
     *
     * @throws org.xml.sax.SAXException Any SAX exception, possibly
     *            wrapping another exception.
     * @see org.xml.sax.ContentHandler#startDocument
     */
    @Override
    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).
Throws:
SAXException – Any SAX exception, possibly
           wrapping another exception.
See Also:
ContentHandler.endDocument/**
     * 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>
     *
     * @throws org.xml.sax.SAXException Any SAX exception, possibly
     *            wrapping another exception.
     * @see org.xml.sax.ContentHandler#endDocument
     */
    @Override
    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).
Params:
prefix – The Namespace prefix being declared.
uri – The Namespace URI mapped to the prefix.
Throws:
SAXException – Any SAX exception, possibly
           wrapping another exception.
See Also:
ContentHandler.startPrefixMapping/**
     * 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.
     * @throws org.xml.sax.SAXException Any SAX exception, possibly
     *            wrapping another exception.
     * @see org.xml.sax.ContentHandler#startPrefixMapping
     */
    @Override
    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.
Params:
prefix – The Namespace prefix being declared.
Throws:
SAXException – Any SAX exception, possibly
           wrapping another exception.
See Also:
ContentHandler.endPrefixMapping/**
     * 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.
     * @throws org.xml.sax.SAXException Any SAX exception, possibly
     *            wrapping another exception.
     * @see org.xml.sax.ContentHandler#endPrefixMapping
     */
    @Override
    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).
Params:
uri – The Namespace URI, or the empty string if the
       element has no Namespace URI or if Namespace
       processing is not being performed.
localName – The local name (without prefix), or the
       empty string if Namespace processing is not being
       performed.
qName – The qualified name (with prefix), or the
       empty string if qualified names are not available.
attributes – The attributes attached to the element.  If
       there are no attributes, it shall be an empty
       Attributes object.
Throws:
SAXException – Any SAX exception, possibly
           wrapping another exception.
See Also:
ContentHandler.startElement/**
     * 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.
     * @throws org.xml.sax.SAXException Any SAX exception, possibly
     *            wrapping another exception.
     * @see org.xml.sax.ContentHandler#startElement
     */
    @Override
    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).
Params:
uri – The Namespace URI, or the empty string if the
       element has no Namespace URI or if Namespace
       processing is not being performed.
localName – The local name (without prefix), or the
       empty string if Namespace processing is not being
       performed.
qName – The qualified name (with prefix), or the
       empty string if qualified names are not available.
Throws:
SAXException – Any SAX exception, possibly
           wrapping another exception.
See Also:
ContentHandler.endElement/**
     * 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.
     * @throws org.xml.sax.SAXException Any SAX exception, possibly
     *            wrapping another exception.
     * @see org.xml.sax.ContentHandler#endElement
     */
    @Override
    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).
Params:
ch – The characters.
start – The start position in the character array.
length – The number of characters to use from the
              character array.
Throws:
SAXException – Any SAX exception, possibly
           wrapping another exception.
See Also:
ContentHandler.characters/**
     * 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.
     * @throws org.xml.sax.SAXException Any SAX exception, possibly
     *            wrapping another exception.
     * @see org.xml.sax.ContentHandler#characters
     */
    @Override
    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).
Params:
ch – The whitespace characters.
start – The start position in the character array.
length – The number of characters to use from the
              character array.
Throws:
SAXException – Any SAX exception, possibly
           wrapping another exception.
See Also:
ContentHandler.ignorableWhitespace/**
     * 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.
     * @throws org.xml.sax.SAXException Any SAX exception, possibly
     *            wrapping another exception.
     * @see org.xml.sax.ContentHandler#ignorableWhitespace
     */
    @Override
    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.
Params:
target – The processing instruction target.
data – The processing instruction data, or null if
            none is supplied.
Throws:
SAXException – Any SAX exception, possibly
           wrapping another exception.
See Also:
ContentHandler.processingInstruction/**
     * 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.
     * @throws org.xml.sax.SAXException Any SAX exception, possibly
     *            wrapping another exception.
     * @see org.xml.sax.ContentHandler#processingInstruction
     */
    @Override
    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.
Params:
name – The name of the skipped entity.
Throws:
SAXException – Any SAX exception, possibly
           wrapping another exception.
See Also:
ContentHandler.processingInstruction/**
     * 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.
     * @throws org.xml.sax.SAXException Any SAX exception, possibly
     *            wrapping another exception.
     * @see org.xml.sax.ContentHandler#processingInstruction
     */
    @Override
    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.
Params:
e – The warning information encoded as an exception.
Throws:
SAXException – Any SAX exception, possibly
           wrapping another exception.
See Also:
ErrorHandler.warning
SAXParseException/**
     * 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.
     * @throws org.xml.sax.SAXException Any SAX exception, possibly
     *            wrapping another exception.
     * @see org.xml.sax.ErrorHandler#warning
     * @see org.xml.sax.SAXParseException
     */
    @Override
    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.
Params:
e – The error information encoded as an exception.
Throws:
SAXException – Any SAX exception, possibly
           wrapping another exception.
See Also:
ErrorHandler.warning
SAXParseException/**
     * 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 error information encoded as an exception.
     * @throws org.xml.sax.SAXException Any SAX exception, possibly
     *            wrapping another exception.
     * @see org.xml.sax.ErrorHandler#warning
     * @see org.xml.sax.SAXParseException
     */
    @Override
    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.
Params:
e – The error information encoded as an exception.
Throws:
SAXException – Any SAX exception, possibly
           wrapping another exception.
See Also:
ErrorHandler.fatalError
SAXParseException/**
     * 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.
     * @throws org.xml.sax.SAXException Any SAX exception, possibly
     *            wrapping another exception.
     * @see org.xml.sax.ErrorHandler#fatalError
     * @see org.xml.sax.SAXParseException
     */
    @Override
    public void fatalError (SAXParseException e)
        throws SAXException
    {
        throw e;
    }

}

// end of DefaultHandler.java