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