1 /*
2 * Copyright (c) 2000, 2020, 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.helpers;
27
28 import java.io.IOException;
29
30 import org.xml.sax.InputSource;
31 import org.xml.sax.Locator;
32 import org.xml.sax.Attributes;
33 import org.xml.sax.EntityResolver;
34 import org.xml.sax.DTDHandler;
35 import org.xml.sax.ContentHandler;
36 import org.xml.sax.ErrorHandler;
37 import org.xml.sax.SAXException;
38 import org.xml.sax.SAXParseException;
39
40
41 /**
42 * Default base class for SAX2 event handlers.
43 *
44 * <p>This class is available as a convenience base class for SAX2
45 * applications: it provides default implementations for all of the
46 * callbacks in the four core SAX2 handler classes:</p>
47 *
48 * <ul>
49 * <li>{@link org.xml.sax.EntityResolver EntityResolver}</li>
50 * <li>{@link org.xml.sax.DTDHandler DTDHandler}</li>
51 * <li>{@link org.xml.sax.ContentHandler ContentHandler}</li>
52 * <li>{@link org.xml.sax.ErrorHandler ErrorHandler}</li>
53 * </ul>
54 *
55 * <p>Application writers can extend this class when they need to
56 * implement only part of an interface; parser writers can
57 * instantiate this class to provide default handlers when the
58 * application has not supplied its own.</p>
59 *
60 * <p>This class replaces the deprecated SAX1
61 * {@link org.xml.sax.HandlerBase HandlerBase} class.</p>
62 *
63 * @since 1.4, SAX 2.0
64 * @author David Megginson,
65 * @see org.xml.sax.EntityResolver
66 * @see org.xml.sax.DTDHandler
67 * @see org.xml.sax.ContentHandler
68 * @see org.xml.sax.ErrorHandler
69 */
70 public class DefaultHandler
71 implements EntityResolver, DTDHandler, ContentHandler, ErrorHandler
72 {
73 /**
74 * Constructs a {@code DefaultHandler}.
75 */
76 public DefaultHandler() {}
77
78 ////////////////////////////////////////////////////////////////////
79 // Default implementation of the EntityResolver interface.
80 ////////////////////////////////////////////////////////////////////
81
82 /**
83 * Resolve an external entity.
84 *
85 * <p>Always return null, so that the parser will use the system
86 * identifier provided in the XML document. This method implements
87 * the SAX default behaviour: application writers can override it
88 * in a subclass to do special translations such as catalog lookups
89 * or URI redirection.</p>
90 *
91 * @param publicId The public identifier, or null if none is
92 * available.
93 * @param systemId The system identifier provided in the XML
94 * document.
95 * @return The new input source, or null to require the
96 * default behaviour.
97 * @throws java.io.IOException If there is an error setting
98 * up the new input source.
99 * @throws org.xml.sax.SAXException Any SAX exception, possibly
100 * wrapping another exception.
101 * @see org.xml.sax.EntityResolver#resolveEntity
102 */
103 @Override
104 public InputSource resolveEntity (String publicId, String systemId)
105 throws IOException, SAXException
106 {
107 return null;
108 }
109
110
111
112 ////////////////////////////////////////////////////////////////////
113 // Default implementation of DTDHandler interface.
114 ////////////////////////////////////////////////////////////////////
115
116
117 /**
118 * Receive notification of a notation declaration.
119 *
120 * <p>By default, do nothing. Application writers may override this
121 * method in a subclass if they wish to keep track of the notations
122 * declared in a document.</p>
123 *
124 * @param name The notation name.
125 * @param publicId The notation public identifier, or null if not
126 * available.
127 * @param systemId The notation system identifier.
128 * @throws org.xml.sax.SAXException Any SAX exception, possibly
129 * wrapping another exception.
130 * @see org.xml.sax.DTDHandler#notationDecl
131 */
132 @Override
133 public void notationDecl (String name, String publicId, String systemId)
134 throws SAXException
135 {
136 // no op
137 }
138
139
140 /**
141 * Receive notification of an unparsed entity declaration.
142 *
143 * <p>By default, do nothing. Application writers may override this
144 * method in a subclass to keep track of the unparsed entities
145 * declared in a document.</p>
146 *
147 * @param name The entity name.
148 * @param publicId The entity public identifier, or null if not
149 * available.
150 * @param systemId The entity system identifier.
151 * @param notationName The name of the associated notation.
152 * @throws org.xml.sax.SAXException Any SAX exception, possibly
153 * wrapping another exception.
154 * @see org.xml.sax.DTDHandler#unparsedEntityDecl
155 */
156 @Override
157 public void unparsedEntityDecl (String name, String publicId,
158 String systemId, String notationName)
159 throws SAXException
160 {
161 // no op
162 }
163
164
165
166 ////////////////////////////////////////////////////////////////////
167 // Default implementation of ContentHandler interface.
168 ////////////////////////////////////////////////////////////////////
169
170
171 /**
172 * Receive a Locator object for document events.
173 *
174 * <p>By default, do nothing. Application writers may override this
175 * method in a subclass if they wish to store the locator for use
176 * with other document events.</p>
177 *
178 * @param locator A locator for all SAX document events.
179 * @see org.xml.sax.ContentHandler#setDocumentLocator
180 * @see org.xml.sax.Locator
181 */
182 @Override
183 public void setDocumentLocator (Locator locator)
184 {
185 // no op
186 }
187
188
189 /**
190 * Receive notification of the beginning of the document.
191 *
192 * <p>By default, do nothing. Application writers may override this
193 * method in a subclass to take specific actions at the beginning
194 * of a document (such as allocating the root node of a tree or
195 * creating an output file).</p>
196 *
197 * @throws org.xml.sax.SAXException Any SAX exception, possibly
198 * wrapping another exception.
199 * @see org.xml.sax.ContentHandler#startDocument
200 */
201 @Override
202 public void startDocument ()
203 throws SAXException
204 {
205 // no op
206 }
207
208
209 /**
210 * Receive notification of the end of the document.
211 *
212 * <p>By default, do nothing. Application writers may override this
213 * method in a subclass to take specific actions at the end
214 * of a document (such as finalising a tree or closing an output
215 * file).</p>
216 *
217 * @throws org.xml.sax.SAXException Any SAX exception, possibly
218 * wrapping another exception.
219 * @see org.xml.sax.ContentHandler#endDocument
220 */
221 @Override
222 public void endDocument ()
223 throws SAXException
224 {
225 // no op
226 }
227
228
229 /**
230 * Receive notification of the start of a Namespace mapping.
231 *
232 * <p>By default, do nothing. Application writers may override this
233 * method in a subclass to take specific actions at the start of
234 * each Namespace prefix scope (such as storing the prefix mapping).</p>
235 *
236 * @param prefix The Namespace prefix being declared.
237 * @param uri The Namespace URI mapped to the prefix.
238 * @throws org.xml.sax.SAXException Any SAX exception, possibly
239 * wrapping another exception.
240 * @see org.xml.sax.ContentHandler#startPrefixMapping
241 */
242 @Override
243 public void startPrefixMapping (String prefix, String uri)
244 throws SAXException
245 {
246 // no op
247 }
248
249
250 /**
251 * Receive notification of the end of a Namespace mapping.
252 *
253 * <p>By default, do nothing. Application writers may override this
254 * method in a subclass to take specific actions at the end of
255 * each prefix mapping.</p>
256 *
257 * @param prefix The Namespace prefix being declared.
258 * @throws org.xml.sax.SAXException Any SAX exception, possibly
259 * wrapping another exception.
260 * @see org.xml.sax.ContentHandler#endPrefixMapping
261 */
262 @Override
263 public void endPrefixMapping (String prefix)
264 throws SAXException
265 {
266 // no op
267 }
268
269
270 /**
271 * Receive notification of the start of an element.
272 *
273 * <p>By default, do nothing. Application writers may override this
274 * method in a subclass to take specific actions at the start of
275 * each element (such as allocating a new tree node or writing
276 * output to a file).</p>
277 *
278 * @param uri The Namespace URI, or the empty string if the
279 * element has no Namespace URI or if Namespace
280 * processing is not being performed.
281 * @param localName The local name (without prefix), or the
282 * empty string if Namespace processing is not being
283 * performed.
284 * @param qName The qualified name (with prefix), or the
285 * empty string if qualified names are not available.
286 * @param attributes The attributes attached to the element. If
287 * there are no attributes, it shall be an empty
288 * Attributes object.
289 * @throws org.xml.sax.SAXException Any SAX exception, possibly
290 * wrapping another exception.
291 * @see org.xml.sax.ContentHandler#startElement
292 */
293 @Override
294 public void startElement (String uri, String localName,
295 String qName, Attributes attributes)
296 throws SAXException
297 {
298 // no op
299 }
300
301
302 /**
303 * Receive notification of the end of an element.
304 *
305 * <p>By default, do nothing. Application writers may override this
306 * method in a subclass to take specific actions at the end of
307 * each element (such as finalising a tree node or writing
308 * output to a file).</p>
309 *
310 * @param uri The Namespace URI, or the empty string if the
311 * element has no Namespace URI or if Namespace
312 * processing is not being performed.
313 * @param localName The local name (without prefix), or the
314 * empty string if Namespace processing is not being
315 * performed.
316 * @param qName The qualified name (with prefix), or the
317 * empty string if qualified names are not available.
318 * @throws org.xml.sax.SAXException Any SAX exception, possibly
319 * wrapping another exception.
320 * @see org.xml.sax.ContentHandler#endElement
321 */
322 @Override
323 public void endElement (String uri, String localName, String qName)
324 throws SAXException
325 {
326 // no op
327 }
328
329
330 /**
331 * Receive notification of character data inside an element.
332 *
333 * <p>By default, do nothing. Application writers may override this
334 * method to take specific actions for each chunk of character data
335 * (such as adding the data to a node or buffer, or printing it to
336 * a file).</p>
337 *
338 * @param ch The characters.
339 * @param start The start position in the character array.
340 * @param length The number of characters to use from the
341 * character array.
342 * @throws org.xml.sax.SAXException Any SAX exception, possibly
343 * wrapping another exception.
344 * @see org.xml.sax.ContentHandler#characters
345 */
346 @Override
347 public void characters (char ch[], int start, int length)
348 throws SAXException
349 {
350 // no op
351 }
352
353
354 /**
355 * Receive notification of ignorable whitespace in element content.
356 *
357 * <p>By default, do nothing. Application writers may override this
358 * method to take specific actions for each chunk of ignorable
359 * whitespace (such as adding data to a node or buffer, or printing
360 * it to a file).</p>
361 *
362 * @param ch The whitespace characters.
363 * @param start The start position in the character array.
364 * @param length The number of characters to use from the
365 * character array.
366 * @throws org.xml.sax.SAXException Any SAX exception, possibly
367 * wrapping another exception.
368 * @see org.xml.sax.ContentHandler#ignorableWhitespace
369 */
370 @Override
371 public void ignorableWhitespace (char ch[], int start, int length)
372 throws SAXException
373 {
374 // no op
375 }
376
377
378 /**
379 * Receive notification of a processing instruction.
380 *
381 * <p>By default, do nothing. Application writers may override this
382 * method in a subclass to take specific actions for each
383 * processing instruction, such as setting status variables or
384 * invoking other methods.</p>
385 *
386 * @param target The processing instruction target.
387 * @param data The processing instruction data, or null if
388 * none is supplied.
389 * @throws org.xml.sax.SAXException Any SAX exception, possibly
390 * wrapping another exception.
391 * @see org.xml.sax.ContentHandler#processingInstruction
392 */
393 @Override
394 public void processingInstruction (String target, String data)
395 throws SAXException
396 {
397 // no op
398 }
399
400
401 /**
402 * Receive notification of a skipped entity.
403 *
404 * <p>By default, do nothing. Application writers may override this
405 * method in a subclass to take specific actions for each
406 * processing instruction, such as setting status variables or
407 * invoking other methods.</p>
408 *
409 * @param name The name of the skipped entity.
410 * @throws org.xml.sax.SAXException Any SAX exception, possibly
411 * wrapping another exception.
412 * @see org.xml.sax.ContentHandler#processingInstruction
413 */
414 @Override
415 public void skippedEntity (String name)
416 throws SAXException
417 {
418 // no op
419 }
420
421
422
423 ////////////////////////////////////////////////////////////////////
424 // Default implementation of the ErrorHandler interface.
425 ////////////////////////////////////////////////////////////////////
426
427
428 /**
429 * Receive notification of a parser warning.
430 *
431 * <p>The default implementation does nothing. Application writers
432 * may override this method in a subclass to take specific actions
433 * for each warning, such as inserting the message in a log file or
434 * printing it to the console.</p>
435 *
436 * @param e The warning information encoded as an exception.
437 * @throws org.xml.sax.SAXException Any SAX exception, possibly
438 * wrapping another exception.
439 * @see org.xml.sax.ErrorHandler#warning
440 * @see org.xml.sax.SAXParseException
441 */
442 @Override
443 public void warning (SAXParseException e)
444 throws SAXException
445 {
446 // no op
447 }
448
449
450 /**
451 * Receive notification of a recoverable parser error.
452 *
453 * <p>The default implementation does nothing. Application writers
454 * may override this method in a subclass to take specific actions
455 * for each error, such as inserting the message in a log file or
456 * printing it to the console.</p>
457 *
458 * @param e The error information encoded as an exception.
459 * @throws org.xml.sax.SAXException Any SAX exception, possibly
460 * wrapping another exception.
461 * @see org.xml.sax.ErrorHandler#warning
462 * @see org.xml.sax.SAXParseException
463 */
464 @Override
465 public void error (SAXParseException e)
466 throws SAXException
467 {
468 // no op
469 }
470
471
472 /**
473 * Report a fatal XML parsing error.
474 *
475 * <p>The default implementation throws a SAXParseException.
476 * Application writers may override this method in a subclass if
477 * they need to take specific actions for each fatal error (such as
478 * collecting all of the errors into a single report): in any case,
479 * the application must stop all regular processing when this
480 * method is invoked, since the document is no longer reliable, and
481 * the parser may no longer report parsing events.</p>
482 *
483 * @param e The error information encoded as an exception.
484 * @throws org.xml.sax.SAXException Any SAX exception, possibly
485 * wrapping another exception.
486 * @see org.xml.sax.ErrorHandler#fatalError
487 * @see org.xml.sax.SAXParseException
488 */
489 @Override
490 public void fatalError (SAXParseException e)
491 throws SAXException
492 {
493 throw e;
494 }
495
496 }
497
498 // end of DefaultHandler.java