1// SAX error handler.
2// http://www.saxproject.org
3// No warranty; no copyright -- use this as you will.
4// $Id: ErrorHandler.java,v 1.10 2004/03/08 13:01:00 dmegginson Exp $
5
6package org.xml.sax;
7
8
9/**
10 * Basic interface for SAX error handlers.
11 *
12 * <blockquote>
13 * <em>This module, both source code and documentation, is in the
14 * Public Domain, and comes with <strong>NO WARRANTY</strong>.</em>
15 * See <a href='http://www.saxproject.org'>http://www.saxproject.org</a>
16 * for further information.
17 * </blockquote>
18 *
19 * <p>If a SAX application needs to implement customized error
20 * handling, it must implement this interface and then register an
21 * instance with the XML reader using the
22 * {@link org.xml.sax.XMLReader#setErrorHandler setErrorHandler}
23 * method.  The parser will then report all errors and warnings
24 * through this interface.</p>
25 *
26 * <p><strong>WARNING:</strong> If an application does <em>not</em>
27 * register an ErrorHandler, XML parsing errors will go unreported,
28 * except that <em>SAXParseException</em>s will be thrown for fatal errors.
29 * In order to detect validity errors, an ErrorHandler that does something
30 * with {@link #error error()} calls must be registered.</p>
31 *
32 * <p>For XML processing errors, a SAX driver must use this interface
33 * in preference to throwing an exception: it is up to the application
34 * to decide whether to throw an exception for different types of
35 * errors and warnings.  Note, however, that there is no requirement that
36 * the parser continue to report additional errors after a call to
37 * {@link #fatalError fatalError}.  In other words, a SAX driver class
38 * may throw an exception after reporting any fatalError.
39 * Also parsers may throw appropriate exceptions for non-XML errors.
40 * For example, {@link XMLReader#parse XMLReader.parse()} would throw
41 * an IOException for errors accessing entities or the document.</p>
42 *
43 * @since SAX 1.0
44 * @author David Megginson
45 * @version 2.0.1+ (sax2r3pre1)
46 * @see org.xml.sax.XMLReader#setErrorHandler
47 * @see org.xml.sax.SAXParseException
48 */
49public interface ErrorHandler {
50
51
52    /**
53     * Receive notification of a warning.
54     *
55     * <p>SAX parsers will use this method to report conditions that
56     * are not errors or fatal errors as defined by the XML
57     * recommendation.  The default behaviour is to take no
58     * action.</p>
59     *
60     * <p>The SAX parser must continue to provide normal parsing events
61     * after invoking this method: it should still be possible for the
62     * application to process the document through to the end.</p>
63     *
64     * <p>Filters may use this method to report other, non-XML warnings
65     * as well.</p>
66     *
67     * @param exception The warning information encapsulated in a
68     *                  SAX parse exception.
69     * @exception org.xml.sax.SAXException Any SAX exception, possibly
70     *            wrapping another exception.
71     * @see org.xml.sax.SAXParseException
72     */
73    public abstract void warning (SAXParseException exception)
74    throws SAXException;
75
76
77    /**
78     * Receive notification of a recoverable error.
79     *
80     * <p>This corresponds to the definition of "error" in section 1.2
81     * of the W3C XML 1.0 Recommendation.  For example, a validating
82     * parser would use this callback to report the violation of a
83     * validity constraint.  The default behaviour is to take no
84     * action.</p>
85     *
86     * <p>The SAX parser must continue to provide normal parsing
87     * events after invoking this method: it should still be possible
88     * for the application to process the document through to the end.
89     * If the application cannot do so, then the parser should report
90     * a fatal error even if the XML recommendation does not require
91     * it to do so.</p>
92     *
93     * <p>Filters may use this method to report other, non-XML errors
94     * as well.</p>
95     *
96     * @param exception The error information encapsulated in a
97     *                  SAX parse exception.
98     * @exception org.xml.sax.SAXException Any SAX exception, possibly
99     *            wrapping another exception.
100     * @see org.xml.sax.SAXParseException
101     */
102    public abstract void error (SAXParseException exception)
103    throws SAXException;
104
105
106    /**
107     * Receive notification of a non-recoverable error.
108     *
109     * <p><strong>There is an apparent contradiction between the
110     * documentation for this method and the documentation for {@link
111     * org.xml.sax.ContentHandler#endDocument}.  Until this ambiguity
112     * is resolved in a future major release, clients should make no
113     * assumptions about whether endDocument() will or will not be
114     * invoked when the parser has reported a fatalError() or thrown
115     * an exception.</strong></p>
116     *
117     * <p>This corresponds to the definition of "fatal error" in
118     * section 1.2 of the W3C XML 1.0 Recommendation.  For example, a
119     * parser would use this callback to report the violation of a
120     * well-formedness constraint.</p>
121     *
122     * <p>The application must assume that the document is unusable
123     * after the parser has invoked this method, and should continue
124     * (if at all) only for the sake of collecting additional error
125     * messages: in fact, SAX parsers are free to stop reporting any
126     * other events once this method has been invoked.</p>
127     *
128     * @param exception The error information encapsulated in a
129     *                  SAX parse exception.
130     * @exception org.xml.sax.SAXException Any SAX exception, possibly
131     *            wrapping another exception.
132     * @see org.xml.sax.SAXParseException
133     */
134    public abstract void fatalError (SAXParseException exception)
135    throws SAXException;
136
137}
138
139// end of ErrorHandler.java
140