1 /*
2 * Copyright (c) 2000, 2019, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation. Oracle designates this
8 * particular file as subject to the "Classpath" exception as provided
9 * by Oracle in the LICENSE file that accompanied this code.
10 *
11 * This code is distributed in the hope that it will be useful, but WITHOUT
12 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
13 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
14 * version 2 for more details (a copy is included in the LICENSE file that
15 * accompanied this code).
16 *
17 * You should have received a copy of the GNU General Public License version
18 * 2 along with this work; if not, write to the Free Software Foundation,
19 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
20 *
21 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
22 * or visit www.oracle.com if you need additional information or have any
23 * questions.
24 */
25
26 package org.xml.sax;
27
28
29 /**
30 * Receive notification of the logical content of a document.
31 *
32 * <p>This is the main interface that most SAX applications
33 * implement: if the application needs to be informed of basic parsing
34 * events, it implements this interface and registers an instance with
35 * the SAX parser using the {@link org.xml.sax.XMLReader#setContentHandler
36 * setContentHandler} method. The parser uses the instance to report
37 * basic document-related events like the start and end of elements
38 * and character data.</p>
39 *
40 * <p>The order of events in this interface is very important, and
41 * mirrors the order of information in the document itself. For
42 * example, all of an element's content (character data, processing
43 * instructions, and/or subelements) will appear, in order, between
44 * the startElement event and the corresponding endElement event.</p>
45 *
46 * <p>This interface is similar to the now-deprecated SAX 1.0
47 * DocumentHandler interface, but it adds support for Namespaces
48 * and for reporting skipped entities (in non-validating XML
49 * processors).</p>
50 *
51 * <p>Implementors should note that there is also a
52 * <code>ContentHandler</code> class in the <code>java.net</code>
53 * package; that means that it's probably a bad idea to do</p>
54 *
55 * <pre>import java.net.*;
56 * import org.xml.sax.*;
57 * </pre>
58 *
59 * <p>In fact, "import ...*" is usually a sign of sloppy programming
60 * anyway, so the user should consider this a feature rather than a
61 * bug.</p>
62 *
63 * @since 1.4, SAX 2.0
64 * @author David Megginson
65 * @see org.xml.sax.XMLReader
66 * @see org.xml.sax.DTDHandler
67 * @see org.xml.sax.ErrorHandler
68 */
69 public interface ContentHandler
70 {
71
72 /**
73 * Receive an object for locating the origin of SAX document events.
74 *
75 * <p>SAX parsers are strongly encouraged (though not absolutely
76 * required) to supply a locator: if it does so, it must supply
77 * the locator to the application by invoking this method before
78 * invoking any of the other methods in the ContentHandler
79 * interface.</p>
80 *
81 * <p>The locator allows the application to determine the end
82 * position of any document-related event, even if the parser is
83 * not reporting an error. Typically, the application will
84 * use this information for reporting its own errors (such as
85 * character content that does not match an application's
86 * business rules). The information returned by the locator
87 * is probably not sufficient for use with a search engine.</p>
88 *
89 * <p>Note that the locator will return correct information only
90 * during the invocation SAX event callbacks after
91 * {@link #startDocument startDocument} returns and before
92 * {@link #endDocument endDocument} is called. The
93 * application should not attempt to use it at any other time.</p>
94 *
95 * @param locator an object that can return the location of
96 * any SAX document event
97 * @see org.xml.sax.Locator
98 */
99 public void setDocumentLocator (Locator locator);
100
101
102 /**
103 * Receive notification of the beginning of a document.
104 *
105 * <p>The SAX parser will invoke this method only once, before any
106 * other event callbacks (except for {@link #setDocumentLocator
107 * setDocumentLocator}).</p>
108 *
109 * @throws org.xml.sax.SAXException any SAX exception, possibly
110 * wrapping another exception
111 * @see #endDocument
112 */
113 public void startDocument ()
114 throws SAXException;
115
116 /**
117 * Receives notification of the XML declaration.
118 *
119 * @implSpec
120 * The default implementation in the SAX API is to do nothing.
121 *
122 * @param version the version string as in the input document, null if not
123 * specified
124 * @param encoding the encoding string as in the input document, null if not
125 * specified
126 * @param standalone the standalone string as in the input document, null if
127 * not specified
128 *
129 * @throws SAXException if the application wants to report an error or
130 * interrupt the parsing process
131 *
132 * @since 14
133 */
134 default void declaration(String version, String encoding, String standalone)
135 throws SAXException
136 {
137 //no op
138 }
139
140 /**
141 * Receive notification of the end of a document.
142 *
143 * <p>
144 * This method is invoked by the parser to signal it has reached the end of
145 * the document after successfully completing the parsing process.
146 * After the event, the parser will return the control to the application.
147 *
148 * @apiNote In case of a fatal error, the parser may choose to stop the
149 * parsing process with a {@link SAXException}, in which case, this method
150 * will never be called. Refer to
151 * {@link ErrorHandler#fatalError(org.xml.sax.SAXParseException)}.
152 *
153 * @throws org.xml.sax.SAXException any SAX exception, possibly
154 * wrapping another exception
155 * @see #startDocument
156 */
157 public void endDocument()
158 throws SAXException;
159
160
161 /**
162 * Begin the scope of a prefix-URI Namespace mapping.
163 *
164 * <p>The information from this event is not necessary for
165 * normal Namespace processing: the SAX XML reader will
166 * automatically replace prefixes for element and attribute
167 * names when the <code>http://xml.org/sax/features/namespaces</code>
168 * feature is <var>true</var> (the default).</p>
169 *
170 * <p>There are cases, however, when applications need to
171 * use prefixes in character data or in attribute values,
172 * where they cannot safely be expanded automatically; the
173 * start/endPrefixMapping event supplies the information
174 * to the application to expand prefixes in those contexts
175 * itself, if necessary.</p>
176 *
177 * <p>Note that start/endPrefixMapping events are not
178 * guaranteed to be properly nested relative to each other:
179 * all startPrefixMapping events will occur immediately before the
180 * corresponding {@link #startElement startElement} event,
181 * and all {@link #endPrefixMapping endPrefixMapping}
182 * events will occur immediately after the corresponding
183 * {@link #endElement endElement} event,
184 * but their order is not otherwise
185 * guaranteed.</p>
186 *
187 * <p>There should never be start/endPrefixMapping events for the
188 * "xml" prefix, since it is predeclared and immutable.</p>
189 *
190 * @param prefix the Namespace prefix being declared.
191 * An empty string is used for the default element namespace,
192 * which has no prefix.
193 * @param uri the Namespace URI the prefix is mapped to
194 * @throws org.xml.sax.SAXException the client may throw
195 * an exception during processing
196 * @see #endPrefixMapping
197 * @see #startElement
198 */
199 public void startPrefixMapping (String prefix, String uri)
200 throws SAXException;
201
202
203 /**
204 * End the scope of a prefix-URI mapping.
205 *
206 * <p>See {@link #startPrefixMapping startPrefixMapping} for
207 * details. These events will always occur immediately after the
208 * corresponding {@link #endElement endElement} event, but the order of
209 * {@link #endPrefixMapping endPrefixMapping} events is not otherwise
210 * guaranteed.</p>
211 *
212 * @param prefix the prefix that was being mapped.
213 * This is the empty string when a default mapping scope ends.
214 * @throws org.xml.sax.SAXException the client may throw
215 * an exception during processing
216 * @see #startPrefixMapping
217 * @see #endElement
218 */
219 public void endPrefixMapping (String prefix)
220 throws SAXException;
221
222
223 /**
224 * Receive notification of the beginning of an element.
225 *
226 * <p>The Parser will invoke this method at the beginning of every
227 * element in the XML document; there will be a corresponding
228 * {@link #endElement endElement} event for every startElement event
229 * (even when the element is empty). All of the element's content will be
230 * reported, in order, before the corresponding endElement
231 * event.</p>
232 *
233 * <p>This event allows up to three name components for each
234 * element:</p>
235 *
236 * <ol>
237 * <li>the Namespace URI;</li>
238 * <li>the local name; and</li>
239 * <li>the qualified (prefixed) name.</li>
240 * </ol>
241 *
242 * <p>Any or all of these may be provided, depending on the
243 * values of the <var>http://xml.org/sax/features/namespaces</var>
244 * and the <var>http://xml.org/sax/features/namespace-prefixes</var>
245 * properties:</p>
246 *
247 * <ul>
248 * <li>the Namespace URI and local name are required when
249 * the namespaces property is <var>true</var> (the default), and are
250 * optional when the namespaces property is <var>false</var> (if one is
251 * specified, both must be);</li>
252 * <li>the qualified name is required when the namespace-prefixes property
253 * is <var>true</var>, and is optional when the namespace-prefixes property
254 * is <var>false</var> (the default).</li>
255 * </ul>
256 *
257 * <p>Note that the attribute list provided will contain only
258 * attributes with explicit values (specified or defaulted):
259 * #IMPLIED attributes will be omitted. The attribute list
260 * will contain attributes used for Namespace declarations
261 * (xmlns* attributes) only if the
262 * <code>http://xml.org/sax/features/namespace-prefixes</code>
263 * property is true (it is false by default, and support for a
264 * true value is optional).</p>
265 *
266 * <p>Like {@link #characters characters()}, attribute values may have
267 * characters that need more than one <code>char</code> value. </p>
268 *
269 * @param uri the Namespace URI, or the empty string if the
270 * element has no Namespace URI or if Namespace
271 * processing is not being performed
272 * @param localName the local name (without prefix), or the
273 * empty string if Namespace processing is not being
274 * performed
275 * @param qName the qualified name (with prefix), or the
276 * empty string if qualified names are not available
277 * @param atts the attributes attached to the element. If
278 * there are no attributes, it shall be an empty
279 * Attributes object. The value of this object after
280 * startElement returns is undefined
281 * @throws org.xml.sax.SAXException any SAX exception, possibly
282 * wrapping another exception
283 * @see #endElement
284 * @see org.xml.sax.Attributes
285 * @see org.xml.sax.helpers.AttributesImpl
286 */
287 public void startElement (String uri, String localName,
288 String qName, Attributes atts)
289 throws SAXException;
290
291
292 /**
293 * Receive notification of the end of an element.
294 *
295 * <p>The SAX parser will invoke this method at the end of every
296 * element in the XML document; there will be a corresponding
297 * {@link #startElement startElement} event for every endElement
298 * event (even when the element is empty).</p>
299 *
300 * <p>For information on the names, see startElement.</p>
301 *
302 * @param uri the Namespace URI, or the empty string if the
303 * element has no Namespace URI or if Namespace
304 * processing is not being performed
305 * @param localName the local name (without prefix), or the
306 * empty string if Namespace processing is not being
307 * performed
308 * @param qName the qualified XML name (with prefix), or the
309 * empty string if qualified names are not available
310 * @throws org.xml.sax.SAXException any SAX exception, possibly
311 * wrapping another exception
312 */
313 public void endElement (String uri, String localName,
314 String qName)
315 throws SAXException;
316
317
318 /**
319 * Receive notification of character data.
320 *
321 * <p>The Parser will call this method to report each chunk of
322 * character data. SAX parsers may return all contiguous character
323 * data in a single chunk, or they may split it into several
324 * chunks; however, all of the characters in any single event
325 * must come from the same external entity so that the Locator
326 * provides useful information.</p>
327 *
328 * <p>The application must not attempt to read from the array
329 * outside of the specified range.</p>
330 *
331 * <p>Individual characters may consist of more than one Java
332 * <code>char</code> value. There are two important cases where this
333 * happens, because characters can't be represented in just sixteen bits.
334 * In one case, characters are represented in a <em>Surrogate Pair</em>,
335 * using two special Unicode values. Such characters are in the so-called
336 * "Astral Planes", with a code point above U+FFFF. A second case involves
337 * composite characters, such as a base character combining with one or
338 * more accent characters. </p>
339 *
340 * <p> Your code should not assume that algorithms using
341 * <code>char</code>-at-a-time idioms will be working in character
342 * units; in some cases they will split characters. This is relevant
343 * wherever XML permits arbitrary characters, such as attribute values,
344 * processing instruction data, and comments as well as in data reported
345 * from this method. It's also generally relevant whenever Java code
346 * manipulates internationalized text; the issue isn't unique to XML.</p>
347 *
348 * <p>Note that some parsers will report whitespace in element
349 * content using the {@link #ignorableWhitespace ignorableWhitespace}
350 * method rather than this one (validating parsers <em>must</em>
351 * do so).</p>
352 *
353 * @param ch the characters from the XML document
354 * @param start the start position in the array
355 * @param length the number of characters to read from the array
356 * @throws org.xml.sax.SAXException any SAX exception, possibly
357 * wrapping another exception
358 * @see #ignorableWhitespace
359 * @see org.xml.sax.Locator
360 */
361 public void characters (char ch[], int start, int length)
362 throws SAXException;
363
364
365 /**
366 * Receive notification of ignorable whitespace in element content.
367 *
368 * <p>Validating Parsers must use this method to report each chunk
369 * of whitespace in element content (see the W3C XML 1.0
370 * recommendation, section 2.10): non-validating parsers may also
371 * use this method if they are capable of parsing and using
372 * content models.</p>
373 *
374 * <p>SAX parsers may return all contiguous whitespace in a single
375 * chunk, or they may split it into several chunks; however, all of
376 * the characters in any single event must come from the same
377 * external entity, so that the Locator provides useful
378 * information.</p>
379 *
380 * <p>The application must not attempt to read from the array
381 * outside of the specified range.</p>
382 *
383 * @param ch the characters from the XML document
384 * @param start the start position in the array
385 * @param length the number of characters to read from the array
386 * @throws org.xml.sax.SAXException any SAX exception, possibly
387 * wrapping another exception
388 * @see #characters
389 */
390 public void ignorableWhitespace (char ch[], int start, int length)
391 throws SAXException;
392
393
394 /**
395 * Receive notification of a processing instruction.
396 *
397 * <p>The Parser will invoke this method once for each processing
398 * instruction found: note that processing instructions may occur
399 * before or after the main document element.</p>
400 *
401 * <p>A SAX parser must never report an XML declaration (XML 1.0,
402 * section 2.8) or a text declaration (XML 1.0, section 4.3.1)
403 * using this method.</p>
404 *
405 * <p>Like {@link #characters characters()}, processing instruction
406 * data may have characters that need more than one <code>char</code>
407 * value. </p>
408 *
409 * @param target the processing instruction target
410 * @param data the processing instruction data, or null if
411 * none was supplied. The data does not include any
412 * whitespace separating it from the target
413 * @throws org.xml.sax.SAXException any SAX exception, possibly
414 * wrapping another exception
415 */
416 public void processingInstruction (String target, String data)
417 throws SAXException;
418
419
420 /**
421 * Receive notification of a skipped entity.
422 * This is not called for entity references within markup constructs
423 * such as element start tags or markup declarations. (The XML
424 * recommendation requires reporting skipped external entities.
425 * SAX also reports internal entity expansion/non-expansion, except
426 * within markup constructs.)
427 *
428 * <p>The Parser will invoke this method each time the entity is
429 * skipped. Non-validating processors may skip entities if they
430 * have not seen the declarations (because, for example, the
431 * entity was declared in an external DTD subset). All processors
432 * may skip external entities, depending on the values of the
433 * <code>http://xml.org/sax/features/external-general-entities</code>
434 * and the
435 * <code>http://xml.org/sax/features/external-parameter-entities</code>
436 * properties.</p>
437 *
438 * @param name the name of the skipped entity. If it is a
439 * parameter entity, the name will begin with '%', and if
440 * it is the external DTD subset, it will be the string
441 * "[dtd]"
442 * @throws org.xml.sax.SAXException any SAX exception, possibly
443 * wrapping another exception
444 */
445 public void skippedEntity (String name)
446 throws SAXException;
447 }
448
449 // end of ContentHandler.java