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package org.xml.sax;



Basic interface for SAX error handlers.

If a SAX application needs to implement customized error handling, it must implement this interface and then register an instance with the XML reader using the setErrorHandler method. The parser will then report all errors and warnings through this interface.


WARNING: If an application does not
register an ErrorHandler, XML parsing errors will go unreported,
except that SAXParseExceptions will be thrown for fatal errors. In order to detect validity errors, an ErrorHandler that does something with error() calls must be registered.


For XML processing errors, a SAX driver must use this interface in preference to throwing an exception: it is up to the application to decide whether to throw an exception for different types of errors and warnings. Note, however, that there is no requirement that the parser continue to report additional errors after a call to fatalError. In other words, a SAX driver class may throw an exception after reporting any fatalError. Also parsers may throw appropriate exceptions for non-XML errors. For example, XMLReader.parse() would throw an IOException for errors accessing entities or the document.


Author:David Megginson
See Also:
Since:1.4, SAX 1.0
/**
 * Basic interface for SAX error handlers.
 *
 * <p>If a SAX application needs to implement customized error
 * handling, it must implement this interface and then register an
 * instance with the XML reader using the
 * {@link org.xml.sax.XMLReader#setErrorHandler setErrorHandler}
 * method.  The parser will then report all errors and warnings
 * through this interface.</p>
 *
 * <p><strong>WARNING:</strong> If an application does <em>not</em>
 * register an ErrorHandler, XML parsing errors will go unreported,
 * except that <em>SAXParseException</em>s will be thrown for fatal errors.
 * In order to detect validity errors, an ErrorHandler that does something
 * with {@link #error error()} calls must be registered.</p>
 *
 * <p>For XML processing errors, a SAX driver must use this interface
 * in preference to throwing an exception: it is up to the application
 * to decide whether to throw an exception for different types of
 * errors and warnings.  Note, however, that there is no requirement that
 * the parser continue to report additional errors after a call to
 * {@link #fatalError fatalError}.  In other words, a SAX driver class
 * may throw an exception after reporting any fatalError.
 * Also parsers may throw appropriate exceptions for non-XML errors.
 * For example, {@link XMLReader#parse XMLReader.parse()} would throw
 * an IOException for errors accessing entities or the document.</p>
 *
 * @since 1.4, SAX 1.0
 * @author David Megginson
 * @see org.xml.sax.XMLReader#setErrorHandler
 * @see org.xml.sax.SAXParseException
 */
public interface ErrorHandler {


    
Receive notification of a warning.

SAX parsers will use this method to report conditions that
are not errors or fatal errors as defined by the XML
recommendation.  The default behaviour is to take no
action.


The SAX parser must continue to provide normal parsing events
after invoking this method: it should still be possible for the
application to process the document through to the end.


Filters may use this method to report other, non-XML warnings
as well.


Params:
  • exception – The warning information encapsulated in a
                 SAX parse exception.
Throws:
  • SAXException – Any SAX exception, possibly
           wrapping another exception.
See Also:
/**
     * Receive notification of a warning.
     *
     * <p>SAX parsers will use this method to report conditions that
     * are not errors or fatal errors as defined by the XML
     * recommendation.  The default behaviour is to take no
     * action.</p>
     *
     * <p>The SAX parser must continue to provide normal parsing events
     * after invoking this method: it should still be possible for the
     * application to process the document through to the end.</p>
     *
     * <p>Filters may use this method to report other, non-XML warnings
     * as well.</p>
     *
     * @param exception The warning information encapsulated in a
     *                  SAX parse exception.
     * @throws org.xml.sax.SAXException Any SAX exception, possibly
     *            wrapping another exception.
     * @see org.xml.sax.SAXParseException
     */
    public abstract void warning (SAXParseException exception)
        throws SAXException;


    
Receive notification of a recoverable error.

This corresponds to the definition of "error" in section 1.2
of the W3C XML 1.0 Recommendation.  For example, a validating
parser would use this callback to report the violation of a
validity constraint.  The default behaviour is to take no
action.


The SAX parser must continue to provide normal parsing
events after invoking this method: it should still be possible
for the application to process the document through to the end.
If the application cannot do so, then the parser should report
a fatal error even if the XML recommendation does not require
it to do so.


Filters may use this method to report other, non-XML errors
as well.


Params:
  • exception – The error information encapsulated in a
                 SAX parse exception.
Throws:
  • SAXException – Any SAX exception, possibly
           wrapping another exception.
See Also:
/**
     * Receive notification of a recoverable error.
     *
     * <p>This corresponds to the definition of "error" in section 1.2
     * of the W3C XML 1.0 Recommendation.  For example, a validating
     * parser would use this callback to report the violation of a
     * validity constraint.  The default behaviour is to take no
     * action.</p>
     *
     * <p>The SAX parser must continue to provide normal parsing
     * events after invoking this method: it should still be possible
     * for the application to process the document through to the end.
     * If the application cannot do so, then the parser should report
     * a fatal error even if the XML recommendation does not require
     * it to do so.</p>
     *
     * <p>Filters may use this method to report other, non-XML errors
     * as well.</p>
     *
     * @param exception The error information encapsulated in a
     *                  SAX parse exception.
     * @throws org.xml.sax.SAXException Any SAX exception, possibly
     *            wrapping another exception.
     * @see org.xml.sax.SAXParseException
     */
    public abstract void error (SAXParseException exception)
        throws SAXException;


    
Receive notification of a non-recoverable, fatal error.


As defined in section 1.2 of the W3C XML 1.0 Recommendation, fatal errors
are those that would make it impossible for a parser to continue normal
processing. These include violation of a well-formedness constraint,
invalid encoding, and forbidden structural errors as described in the
W3C XML 1.0 Recommendation.

Params:
Throws:
  • SAXException – if the application chooses to discontinue the parsing
API Note:An application must assume that the parser can no longer perform normal processing after reporting a fatal error and may stop by throwing a SAXException without calling ContentHandler.endDocument(). In addition, the parser cannot be expected to be able to return accurate information about the logical structure on the rest of the document even if it may be able to resume parsing.
Implementation Note:After invoking this method, the parser may stop processing by throwing a SAXException, or implement a feature that can direct it to continue after a fatal error. In the later case, it may report events on the rest of the document without any guarantee of correctness.
/**
     * Receive notification of a non-recoverable, fatal error.
     *
     * <p>
     * As defined in section 1.2 of the W3C XML 1.0 Recommendation, fatal errors
     * are those that would make it impossible for a parser to continue normal
     * processing. These include violation of a well-formedness constraint,
     * invalid encoding, and forbidden structural errors as described in the
     * W3C XML 1.0 Recommendation.
     *
     * @apiNote An application must assume that the parser can no longer perform
     * normal processing after reporting a fatal error and may stop by throwing
     * a {@link SAXException} without calling {@link ContentHandler#endDocument()}.
     * In addition, the parser cannot be expected to be able to return accurate
     * information about the logical structure on the rest of the document even
     * if it may be able to resume parsing.
     *
     * @implNote After invoking this method, the parser may stop processing by
     * throwing a {@link SAXException}, or implement a feature that can direct
     * it to continue after a fatal error. In the later case, it may report
     * events on the rest of the document without any guarantee of correctness.
     *
     * @param exception The error information encapsulated in a
     *                  {@link SAXParseException}.
     * @throws SAXException if the application chooses to discontinue the parsing
     */
    public abstract void fatalError (SAXParseException exception)
        throws SAXException;

}

// end of ErrorHandler.java