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6
7 package org.xml.sax;
8
9
10 /***
11 * Receive notification of the logical content of a document.
12 *
13 * <blockquote>
14 * <em>This module, both source code and documentation, is in the
15 * Public Domain, and comes with <strong>NO WARRANTY</strong>.</em>
16 * See <a href='http://www.saxproject.org'>http://www.saxproject.org</a>
17 * for further information.
18 * </blockquote>
19 *
20 * <p>This is the main interface that most SAX applications
21 * implement: if the application needs to be informed of basic parsing
22 * events, it implements this interface and registers an instance with
23 * the SAX parser using the {@link org.xml.sax.XMLReader#setContentHandler
24 * setContentHandler} method. The parser uses the instance to report
25 * basic document-related events like the start and end of elements
26 * and character data.</p>
27 *
28 * <p>The order of events in this interface is very important, and
29 * mirrors the order of information in the document itself. For
30 * example, all of an element's content (character data, processing
31 * instructions, and/or subelements) will appear, in order, between
32 * the startElement event and the corresponding endElement event.</p>
33 *
34 * <p>This interface is similar to the now-deprecated SAX 1.0
35 * DocumentHandler interface, but it adds support for Namespaces
36 * and for reporting skipped entities (in non-validating XML
37 * processors).</p>
38 *
39 * <p>Implementors should note that there is also a Java class
40 * {@link java.net.ContentHandler ContentHandler} in the java.net
41 * package; that means that it's probably a bad idea to do</p>
42 *
43 * <blockquote>
44 * import java.net.*;
45 * import org.xml.sax.*;
46 * </blockquote>
47 *
48 * <p>In fact, "import ...*" is usually a sign of sloppy programming
49 * anyway, so the user should consider this a feature rather than a
50 * bug.</p>
51 *
52 * @since SAX 2.0
53 * @author David Megginson
54 * @version 2.0.1+ (sax2r3pre1)
55 * @see org.xml.sax.XMLReader
56 * @see org.xml.sax.DTDHandler
57 * @see org.xml.sax.ErrorHandler
58 */
59 public interface ContentHandler
60 {
61
62 /***
63 * Receive an object for locating the origin of SAX document events.
64 *
65 * <p>SAX parsers are strongly encouraged (though not absolutely
66 * required) to supply a locator: if it does so, it must supply
67 * the locator to the application by invoking this method before
68 * invoking any of the other methods in the ContentHandler
69 * interface.</p>
70 *
71 * <p>The locator allows the application to determine the end
72 * position of any document-related event, even if the parser is
73 * not reporting an error. Typically, the application will
74 * use this information for reporting its own errors (such as
75 * character content that does not match an application's
76 * business rules). The information returned by the locator
77 * is probably not sufficient for use with a search engine.</p>
78 *
79 * <p>Note that the locator will return correct information only
80 * during the invocation SAX event callbacks after
81 * {@link #startDocument startDocument} returns and before
82 * {@link #endDocument endDocument} is called. The
83 * application should not attempt to use it at any other time.</p>
84 *
85 * @param locator An object that can return the location of
86 * any SAX document event.
87 * @see org.xml.sax.Locator
88 */
89 public void setDocumentLocator (Locator locator);
90
91
92 /***
93 * Receive notification of the beginning of a document.
94 *
95 * <p>The SAX parser will invoke this method only once, before any
96 * other event callbacks (except for {@link #setDocumentLocator
97 * setDocumentLocator}).</p>
98 *
99 * @exception org.xml.sax.SAXException Any SAX exception, possibly
100 * wrapping another exception.
101 * @see #endDocument
102 */
103 public void startDocument ()
104 throws SAXException;
105
106
107 /***
108 * Receive notification of the end of a document.
109 *
110 * <p><strong>There is an apparent contradiction between the
111 * documentation for this method and the documentation for {@link
112 * org.xml.sax.ErrorHandler#fatalError}. Until this ambiguity is
113 * resolved in a future major release, clients should make no
114 * assumptions about whether endDocument() will or will not be
115 * invoked when the parser has reported a fatalError() or thrown
116 * an exception.</strong></p>
117 *
118 * <p>The SAX parser will invoke this method only once, and it will
119 * be the last method invoked during the parse. The parser shall
120 * not invoke this method until it has either abandoned parsing
121 * (because of an unrecoverable error) or reached the end of
122 * input.</p>
123 *
124 * @exception org.xml.sax.SAXException Any SAX exception, possibly
125 * wrapping another exception.
126 * @see #startDocument
127 */
128 public void endDocument()
129 throws SAXException;
130
131
132 /***
133 * Begin the scope of a prefix-URI Namespace mapping.
134 *
135 * <p>The information from this event is not necessary for
136 * normal Namespace processing: the SAX XML reader will
137 * automatically replace prefixes for element and attribute
138 * names when the <code>http://xml.org/sax/features/namespaces</code>
139 * feature is <var>true</var> (the default).</p>
140 *
141 * <p>There are cases, however, when applications need to
142 * use prefixes in character data or in attribute values,
143 * where they cannot safely be expanded automatically; the
144 * start/endPrefixMapping event supplies the information
145 * to the application to expand prefixes in those contexts
146 * itself, if necessary.</p>
147 *
148 * <p>Note that start/endPrefixMapping events are not
149 * guaranteed to be properly nested relative to each other:
150 * all startPrefixMapping events will occur immediately before the
151 * corresponding {@link #startElement startElement} event,
152 * and all {@link #endPrefixMapping endPrefixMapping}
153 * events will occur immediately after the corresponding
154 * {@link #endElement endElement} event,
155 * but their order is not otherwise
156 * guaranteed.</p>
157 *
158 * <p>There should never be start/endPrefixMapping events for the
159 * "xml" prefix, since it is predeclared and immutable.</p>
160 *
161 * @param prefix The Namespace prefix being declared.
162 * An empty string is used for the default element namespace,
163 * which has no prefix.
164 * @param uri The Namespace URI the prefix is mapped to.
165 * @exception org.xml.sax.SAXException The client may throw
166 * an exception during processing.
167 * @see #endPrefixMapping
168 * @see #startElement
169 */
170 public void startPrefixMapping (String prefix, String uri)
171 throws SAXException;
172
173
174 /***
175 * End the scope of a prefix-URI mapping.
176 *
177 * <p>See {@link #startPrefixMapping startPrefixMapping} for
178 * details. These events will always occur immediately after the
179 * corresponding {@link #endElement endElement} event, but the order of
180 * {@link #endPrefixMapping endPrefixMapping} events is not otherwise
181 * guaranteed.</p>
182 *
183 * @param prefix The prefix that was being mapped.
184 * This is the empty string when a default mapping scope ends.
185 * @exception org.xml.sax.SAXException The client may throw
186 * an exception during processing.
187 * @see #startPrefixMapping
188 * @see #endElement
189 */
190 public void endPrefixMapping (String prefix)
191 throws SAXException;
192
193
194 /***
195 * Receive notification of the beginning of an element.
196 *
197 * <p>The Parser will invoke this method at the beginning of every
198 * element in the XML document; there will be a corresponding
199 * {@link #endElement endElement} event for every startElement event
200 * (even when the element is empty). All of the element's content will be
201 * reported, in order, before the corresponding endElement
202 * event.</p>
203 *
204 * <p>This event allows up to three name components for each
205 * element:</p>
206 *
207 * <ol>
208 * <li>the Namespace URI;</li>
209 * <li>the local name; and</li>
210 * <li>the qualified (prefixed) name.</li>
211 * </ol>
212 *
213 * <p>Any or all of these may be provided, depending on the
214 * values of the <var>http://xml.org/sax/features/namespaces</var>
215 * and the <var>http://xml.org/sax/features/namespace-prefixes</var>
216 * properties:</p>
217 *
218 * <ul>
219 * <li>the Namespace URI and local name are required when
220 * the namespaces property is <var>true</var> (the default), and are
221 * optional when the namespaces property is <var>false</var> (if one is
222 * specified, both must be);</li>
223 * <li>the qualified name is required when the namespace-prefixes property
224 * is <var>true</var>, and is optional when the namespace-prefixes property
225 * is <var>false</var> (the default).</li>
226 * </ul>
227 *
228 * <p>Note that the attribute list provided will contain only
229 * attributes with explicit values (specified or defaulted):
230 * #IMPLIED attributes will be omitted. The attribute list
231 * will contain attributes used for Namespace declarations
232 * (xmlns* attributes) only if the
233 * <code>http://xml.org/sax/features/namespace-prefixes</code>
234 * property is true (it is false by default, and support for a
235 * true value is optional).</p>
236 *
237 * <p>Like {@link #characters characters()}, attribute values may have
238 * characters that need more than one <code>char</code> value. </p>
239 *
240 * @param uri The Namespace URI, or the empty string if the
241 * element has no Namespace URI or if Namespace
242 * processing is not being performed.
243 * @param localName The local name (without prefix), or the
244 * empty string if Namespace processing is not being
245 * performed.
246 * @param qName The qualified name (with prefix), or the
247 * empty string if qualified names are not available.
248 * @param atts The attributes attached to the element. If
249 * there are no attributes, it shall be an empty
250 * Attributes object.
251 * @exception org.xml.sax.SAXException Any SAX exception, possibly
252 * wrapping another exception.
253 * @see #endElement
254 * @see org.xml.sax.Attributes
255 */
256 public void startElement (String uri, String localName,
257 String qName, Attributes atts)
258 throws SAXException;
259
260
261 /***
262 * Receive notification of the end of an element.
263 *
264 * <p>The SAX parser will invoke this method at the end of every
265 * element in the XML document; there will be a corresponding
266 * {@link #startElement startElement} event for every endElement
267 * event (even when the element is empty).</p>
268 *
269 * <p>For information on the names, see startElement.</p>
270 *
271 * @param uri The Namespace URI, or the empty string if the
272 * element has no Namespace URI or if Namespace
273 * processing is not being performed.
274 * @param localName The local name (without prefix), or the
275 * empty string if Namespace processing is not being
276 * performed.
277 * @param qName The qualified XML name (with prefix), or the
278 * empty string if qualified names are not available.
279 * @exception org.xml.sax.SAXException Any SAX exception, possibly
280 * wrapping another exception.
281 */
282 public void endElement (String uri, String localName,
283 String qName)
284 throws SAXException;
285
286
287 /***
288 * Receive notification of character data.
289 *
290 * <p>The Parser will call this method to report each chunk of
291 * character data. SAX parsers may return all contiguous character
292 * data in a single chunk, or they may split it into several
293 * chunks; however, all of the characters in any single event
294 * must come from the same external entity so that the Locator
295 * provides useful information.</p>
296 *
297 * <p>The application must not attempt to read from the array
298 * outside of the specified range.</p>
299 *
300 * <p>Individual characters may consist of more than one Java
301 * <code>char</code> value. There are two important cases where this
302 * happens, because characters can't be represented in just sixteen bits.
303 * In one case, characters are represented in a <em>Surrogate Pair</em>,
304 * using two special Unicode values. Such characters are in the so-called
305 * "Astral Planes", with a code point above U+FFFF. A second case involves
306 * composite characters, such as a base character combining with one or
307 * more accent characters. </p>
308 *
309 * <p> Your code should not assume that algorithms using
310 * <code>char</code>-at-a-time idioms will be working in character
311 * units; in some cases they will split characters. This is relevant
312 * wherever XML permits arbitrary characters, such as attribute values,
313 * processing instruction data, and comments as well as in data reported
314 * from this method. It's also generally relevant whenever Java code
315 * manipulates internationalized text; the issue isn't unique to XML.</p>
316 *
317 * <p>Note that some parsers will report whitespace in element
318 * content using the {@link #ignorableWhitespace ignorableWhitespace}
319 * method rather than this one (validating parsers <em>must</em>
320 * do so).</p>
321 *
322 * @param ch The characters from the XML document.
323 * @param start The start position in the array.
324 * @param length The number of characters to read from the array.
325 * @exception org.xml.sax.SAXException Any SAX exception, possibly
326 * wrapping another exception.
327 * @see #ignorableWhitespace
328 * @see org.xml.sax.Locator
329 */
330 public void characters (char ch[], int start, int length)
331 throws SAXException;
332
333
334 /***
335 * Receive notification of ignorable whitespace in element content.
336 *
337 * <p>Validating Parsers must use this method to report each chunk
338 * of whitespace in element content (see the W3C XML 1.0
339 * recommendation, section 2.10): non-validating parsers may also
340 * use this method if they are capable of parsing and using
341 * content models.</p>
342 *
343 * <p>SAX parsers may return all contiguous whitespace in a single
344 * chunk, or they may split it into several chunks; however, all of
345 * the characters in any single event must come from the same
346 * external entity, so that the Locator provides useful
347 * information.</p>
348 *
349 * <p>The application must not attempt to read from the array
350 * outside of the specified range.</p>
351 *
352 * @param ch The characters from the XML document.
353 * @param start The start position in the array.
354 * @param length The number of characters to read from the array.
355 * @exception org.xml.sax.SAXException Any SAX exception, possibly
356 * wrapping another exception.
357 * @see #characters
358 */
359 public void ignorableWhitespace (char ch[], int start, int length)
360 throws SAXException;
361
362
363 /***
364 * Receive notification of a processing instruction.
365 *
366 * <p>The Parser will invoke this method once for each processing
367 * instruction found: note that processing instructions may occur
368 * before or after the main document element.</p>
369 *
370 * <p>A SAX parser must never report an XML declaration (XML 1.0,
371 * section 2.8) or a text declaration (XML 1.0, section 4.3.1)
372 * using this method.</p>
373 *
374 * <p>Like {@link #characters characters()}, processing instruction
375 * data may have characters that need more than one <code>char</code>
376 * value. </p>
377 *
378 * @param target The processing instruction target.
379 * @param data The processing instruction data, or null if
380 * none was supplied. The data does not include any
381 * whitespace separating it from the target.
382 * @exception org.xml.sax.SAXException Any SAX exception, possibly
383 * wrapping another exception.
384 */
385 public void processingInstruction (String target, String data)
386 throws SAXException;
387
388
389 /***
390 * Receive notification of a skipped entity.
391 * This is not called for entity references within markup constructs
392 * such as element start tags or markup declarations. (The XML
393 * recommendation requires reporting skipped external entities.
394 * SAX also reports internal entity expansion/non-expansion, except
395 * within markup constructs.)
396 *
397 * <p>The Parser will invoke this method each time the entity is
398 * skipped. Non-validating processors may skip entities if they
399 * have not seen the declarations (because, for example, the
400 * entity was declared in an external DTD subset). All processors
401 * may skip external entities, depending on the values of the
402 * <code>http://xml.org/sax/features/external-general-entities</code>
403 * and the
404 * <code>http://xml.org/sax/features/external-parameter-entities</code>
405 * properties.</p>
406 *
407 * @param name The name of the skipped entity. If it is a
408 * parameter entity, the name will begin with '%', and if
409 * it is the external DTD subset, it will be the string
410 * "[dtd]".
411 * @exception org.xml.sax.SAXException Any SAX exception, possibly
412 * wrapping another exception.
413 */
414 public void skippedEntity (String name)
415 throws SAXException;
416 }
417
418