HandlerBase


1   // SAX default handler base class.
2   // http://www.saxproject.org
3   // No warranty; no copyright -- use this as you will.
4   // $Id: HandlerBase.java,v 1.1.24.1 2004/05/01 08:34:39 jsuttor Exp $
5   
6   package org.xml.sax;
7   
8   /**
9    * Default base class for handlers.
10   *
11   * <blockquote>
12   * <em>This module, both source code and documentation, is in the
13   * Public Domain, and comes with <strong>NO WARRANTY</strong>.</em>
14   * See <a HREF='http://www.saxproject.org'>http://www.saxproject.org</a>
15   * for further information.
16   * </blockquote>
17   *
18   * <p>This class implements the default behaviour for four SAX1
19   * interfaces: EntityResolver, DTDHandler, DocumentHandler,
20   * and ErrorHandler.  It is now obsolete, but is included in SAX2 to
21   * support legacy SAX1 applications.  SAX2 applications should use
22   * the {@link org.xml.sax.helpers.DefaultHandler DefaultHandler}
23   * class instead.</p>
24   *
25   * <p>Application writers can extend this class when they need to
26   * implement only part of an interface; parser writers can
27   * instantiate this class to provide default handlers when the
28   * application has not supplied its own.</p>
29   *
30   * <p>Note that the use of this class is optional.</p>
31   *
32   * @deprecated This class works with the deprecated
33   *             {@link org.xml.sax.DocumentHandler DocumentHandler}
34   *             interface.  It has been replaced by the SAX2
35   *             {@link org.xml.sax.helpers.DefaultHandler DefaultHandler}
36   *             class.
37   * @since SAX 1.0
38   * @author David Megginson
39   * @version 2.0.1 (sax2r2)
40   * @see org.xml.sax.EntityResolver
41   * @see org.xml.sax.DTDHandler
42   * @see org.xml.sax.DocumentHandler
43   * @see org.xml.sax.ErrorHandler
44   */
45  public class HandlerBase
46      implements EntityResolver  , DTDHandler  , DocumentHandler  , ErrorHandler  
47  {
48      
49  
50      ////////////////////////////////////////////////////////////////////
51      // Default implementation of the EntityResolver interface.
52      ////////////////////////////////////////////////////////////////////
53      
54      /**
55       * Resolve an external entity.
56       *
57       * <p>Always return null, so that the parser will use the system
58       * identifier provided in the XML document.  This method implements
59       * the SAX default behaviour: application writers can override it
60       * in a subclass to do special translations such as catalog lookups
61       * or URI redirection.</p>
62       *
63       * @param publicId The public identifer, or null if none is
64       *                 available.
65       * @param systemId The system identifier provided in the XML 
66       *                 document.
67       * @return The new input source, or null to require the
68       *         default behaviour.
69       * @exception org.xml.sax.SAXException Any SAX exception, possibly
70       *            wrapping another exception.
71       * @see org.xml.sax.EntityResolver#resolveEntity
72       */
73      public InputSource   resolveEntity (String   publicId, String   systemId)
74      throws SAXException  
75      {
76      return null;
77      }
78      
79      
80  
81      ////////////////////////////////////////////////////////////////////
82      // Default implementation of DTDHandler interface.
83      ////////////////////////////////////////////////////////////////////
84      
85      
86      /**
87       * Receive notification of a notation declaration.
88       *
89       * <p>By default, do nothing.  Application writers may override this
90       * method in a subclass if they wish to keep track of the notations
91       * declared in a document.</p>
92       *
93       * @param name The notation name.
94       * @param publicId The notation public identifier, or null if not
95       *                 available.
96       * @param systemId The notation system identifier.
97       * @see org.xml.sax.DTDHandler#notationDecl
98       */
99      public void notationDecl (String   name, String   publicId, String   systemId)
100     {
101     // no op
102     }
103     
104     
105     /**
106      * Receive notification of an unparsed entity declaration.
107      *
108      * <p>By default, do nothing.  Application writers may override this
109      * method in a subclass to keep track of the unparsed entities
110      * declared in a document.</p>
111      *
112      * @param name The entity name.
113      * @param publicId The entity public identifier, or null if not
114      *                 available.
115      * @param systemId The entity system identifier.
116      * @param notationName The name of the associated notation.
117      * @see org.xml.sax.DTDHandler#unparsedEntityDecl
118      */
119     public void unparsedEntityDecl (String   name, String   publicId,
120                     String   systemId, String   notationName)
121     {
122     // no op
123     }
124     
125     
126 
127     ////////////////////////////////////////////////////////////////////
128     // Default implementation of DocumentHandler interface.
129     ////////////////////////////////////////////////////////////////////
130     
131     
132     /**
133      * Receive a Locator object for document events.
134      *
135      * <p>By default, do nothing.  Application writers may override this
136      * method in a subclass if they wish to store the locator for use
137      * with other document events.</p>
138      *
139      * @param locator A locator for all SAX document events.
140      * @see org.xml.sax.DocumentHandler#setDocumentLocator
141      * @see org.xml.sax.Locator
142      */
143     public void setDocumentLocator (Locator   locator)
144     {
145     // no op
146     }
147     
148     
149     /**
150      * Receive notification of the beginning of the document.
151      *
152      * <p>By default, do nothing.  Application writers may override this
153      * method in a subclass to take specific actions at the beginning
154      * of a document (such as allocating the root node of a tree or
155      * creating an output file).</p>
156      *
157      * @exception org.xml.sax.SAXException Any SAX exception, possibly
158      *            wrapping another exception.
159      * @see org.xml.sax.DocumentHandler#startDocument
160      */
161     public void startDocument ()
162     throws SAXException  
163     {
164     // no op
165     }
166     
167     
168     /**
169      * Receive notification of the end of the document.
170      *
171      * <p>By default, do nothing.  Application writers may override this
172      * method in a subclass to take specific actions at the beginning
173      * of a document (such as finalising a tree or closing an output
174      * file).</p>
175      *
176      * @exception org.xml.sax.SAXException Any SAX exception, possibly
177      *            wrapping another exception.
178      * @see org.xml.sax.DocumentHandler#endDocument
179      */
180     public void endDocument ()
181     throws SAXException  
182     {
183     // no op
184     }
185     
186     
187     /**
188      * Receive notification of the start of an element.
189      *
190      * <p>By default, do nothing.  Application writers may override this
191      * method in a subclass to take specific actions at the start of
192      * each element (such as allocating a new tree node or writing
193      * output to a file).</p>
194      *
195      * @param name The element type name.
196      * @param attributes The specified or defaulted attributes.
197      * @exception org.xml.sax.SAXException Any SAX exception, possibly
198      *            wrapping another exception.
199      * @see org.xml.sax.DocumentHandler#startElement
200      */
201     public void startElement (String   name, AttributeList   attributes)
202     throws SAXException  
203     {
204     // no op
205     }
206     
207     
208     /**
209      * Receive notification of the end of an element.
210      *
211      * <p>By default, do nothing.  Application writers may override this
212      * method in a subclass to take specific actions at the end of
213      * each element (such as finalising a tree node or writing
214      * output to a file).</p>
215      *
216      * @param name the element name
217      * @exception org.xml.sax.SAXException Any SAX exception, possibly
218      *            wrapping another exception.
219      * @see org.xml.sax.DocumentHandler#endElement
220      */
221     public void endElement (String   name)
222     throws SAXException  
223     {
224     // no op
225     }
226     
227     
228     /**
229      * Receive notification of character data inside an element.
230      *
231      * <p>By default, do nothing.  Application writers may override this
232      * method to take specific actions for each chunk of character data
233      * (such as adding the data to a node or buffer, or printing it to
234      * a file).</p>
235      *
236      * @param ch The characters.
237      * @param start The start position in the character array.
238      * @param length The number of characters to use from the
239      *               character array.
240      * @exception org.xml.sax.SAXException Any SAX exception, possibly
241      *            wrapping another exception.
242      * @see org.xml.sax.DocumentHandler#characters
243      */
244     public void characters (char ch[], int start, int length)
245     throws SAXException  
246     {
247     // no op
248     }
249     
250     
251     /**
252      * Receive notification of ignorable whitespace in element content.
253      *
254      * <p>By default, do nothing.  Application writers may override this
255      * method to take specific actions for each chunk of ignorable
256      * whitespace (such as adding data to a node or buffer, or printing
257      * it to a file).</p>
258      *
259      * @param ch The whitespace characters.
260      * @param start The start position in the character array.
261      * @param length The number of characters to use from the
262      *               character array.
263      * @exception org.xml.sax.SAXException Any SAX exception, possibly
264      *            wrapping another exception.
265      * @see org.xml.sax.DocumentHandler#ignorableWhitespace
266      */
267     public void ignorableWhitespace (char ch[], int start, int length)
268     throws SAXException  
269     {
270     // no op
271     }
272     
273     
274     /**
275      * Receive notification of a processing instruction.
276      *
277      * <p>By default, do nothing.  Application writers may override this
278      * method in a subclass to take specific actions for each
279      * processing instruction, such as setting status variables or
280      * invoking other methods.</p>
281      *
282      * @param target The processing instruction target.
283      * @param data The processing instruction data, or null if
284      *             none is supplied.
285      * @exception org.xml.sax.SAXException Any SAX exception, possibly
286      *            wrapping another exception.
287      * @see org.xml.sax.DocumentHandler#processingInstruction
288      */
289     public void processingInstruction (String   target, String   data)
290     throws SAXException  
291     {
292     // no op
293     }
294     
295     
296 
297     ////////////////////////////////////////////////////////////////////
298     // Default implementation of the ErrorHandler interface.
299     ////////////////////////////////////////////////////////////////////
300     
301     
302     /**
303      * Receive notification of a parser warning.
304      *
305      * <p>The default implementation does nothing.  Application writers
306      * may override this method in a subclass to take specific actions
307      * for each warning, such as inserting the message in a log file or
308      * printing it to the console.</p>
309      *
310      * @param e The warning information encoded as an exception.
311      * @exception org.xml.sax.SAXException Any SAX exception, possibly
312      *            wrapping another exception.
313      * @see org.xml.sax.ErrorHandler#warning
314      * @see org.xml.sax.SAXParseException
315      */
316     public void warning (SAXParseException   e)
317     throws SAXException  
318     {
319     // no op
320     }
321     
322     
323     /**
324      * Receive notification of a recoverable parser error.
325      *
326      * <p>The default implementation does nothing.  Application writers
327      * may override this method in a subclass to take specific actions
328      * for each error, such as inserting the message in a log file or
329      * printing it to the console.</p>
330      *
331      * @param e The warning information encoded as an exception.
332      * @exception org.xml.sax.SAXException Any SAX exception, possibly
333      *            wrapping another exception.
334      * @see org.xml.sax.ErrorHandler#warning
335      * @see org.xml.sax.SAXParseException
336      */
337     public void error (SAXParseException   e)
338     throws SAXException  
339     {
340     // no op
341     }
342     
343     
344     /**
345      * Report a fatal XML parsing error.
346      *
347      * <p>The default implementation throws a SAXParseException.
348      * Application writers may override this method in a subclass if
349      * they need to take specific actions for each fatal error (such as
350      * collecting all of the errors into a single report): in any case,
351      * the application must stop all regular processing when this
352      * method is invoked, since the document is no longer reliable, and
353      * the parser may no longer report parsing events.</p>
354      *
355      * @param e The error information encoded as an exception.
356      * @exception org.xml.sax.SAXException Any SAX exception, possibly
357      *            wrapping another exception.
358      * @see org.xml.sax.ErrorHandler#fatalError
359      * @see org.xml.sax.SAXParseException
360      */
361     public void fatalError (SAXParseException   e)
362     throws SAXException  
363     {
364     throw e;
365     }
366     
367 }
368 
369 // end of HandlerBase.java
370
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