Java > Open Source Codes > org > xml > sax > helpers > XMLFilterImpl


1 // XMLFilterImpl.java - base SAX2 filter implementation.
2 // http://www.saxproject.org
3 // Written by David Megginson
4 // NO WARRANTY! This class is in the Public Domain.
5 // $Id: XMLFilterImpl.java,v 1.2.22.1 2004/05/01 08:34:46 jsuttor Exp $
6
7 package org.xml.sax.helpers;
8
9 import java.io.IOException ;
10
11 import org.xml.sax.XMLReader ;
12 import org.xml.sax.XMLFilter ;
13 import org.xml.sax.InputSource ;
14 import org.xml.sax.Locator ;
15 import org.xml.sax.Attributes ;
16 import org.xml.sax.EntityResolver ;
17 import org.xml.sax.DTDHandler ;
18 import org.xml.sax.ContentHandler ;
19 import org.xml.sax.ErrorHandler ;
20 import org.xml.sax.SAXException ;
21 import org.xml.sax.SAXParseException ;
22 import org.xml.sax.SAXNotSupportedException ;
23 import org.xml.sax.SAXNotRecognizedException ;
24
25
26 /**
27  * Base class for deriving an XML filter.
28  *
29  * <blockquote>
30  * <em>This module, both source code and documentation, is in the
31  * Public Domain, and comes with <strong>NO WARRANTY</strong>.</em>
32  * See <a HREF='http://www.saxproject.org'>http://www.saxproject.org</a>
33  * for further information.
34  * </blockquote>
35  *
36  * <p>This class is designed to sit between an {@link org.xml.sax.XMLReader
37  * XMLReader} and the client application's event handlers. By default, it
38  * does nothing but pass requests up to the reader and events
39  * on to the handlers unmodified, but subclasses can override
40  * specific methods to modify the event stream or the configuration
41  * requests as they pass through.</p>
42  *
43  * @since SAX 2.0
44  * @author David Megginson
45  * @version 2.0.1 (sax2r2)
46  * @see org.xml.sax.XMLFilter
47  * @see org.xml.sax.XMLReader
48  * @see org.xml.sax.EntityResolver
49  * @see org.xml.sax.DTDHandler
50  * @see org.xml.sax.ContentHandler
51  * @see org.xml.sax.ErrorHandler
52  */
53 public class XMLFilterImpl
54     implements XMLFilter , EntityResolver , DTDHandler , ContentHandler , ErrorHandler
55 {
56
57 
58     ////////////////////////////////////////////////////////////////////
59 // Constructors.
60 ////////////////////////////////////////////////////////////////////
61
62
63     /**
64      * Construct an empty XML filter, with no parent.
65      *
66      * <p>This filter will have no parent: you must assign a parent
67      * before you start a parse or do any configuration with
68      * setFeature or setProperty, unless you use this as a pure event
69      * consumer rather than as an {@link XMLReader}.</p>
70      *
71      * @see org.xml.sax.XMLReader#setFeature
72      * @see org.xml.sax.XMLReader#setProperty
73      * @see #setParent
74      */
75     public XMLFilterImpl ()
76     {
77     super();
78     }
79
80
81     /**
82      * Construct an XML filter with the specified parent.
83      *
84      * @see #setParent
85      * @see #getParent
86      */
87     public XMLFilterImpl (XMLReader parent)
88     {
89         super();
90     setParent(parent);
91     }
92
93
94 
95     ////////////////////////////////////////////////////////////////////
96 // Implementation of org.xml.sax.XMLFilter.
97 ////////////////////////////////////////////////////////////////////
98
99
100     /**
101      * Set the parent reader.
102      *
103      * <p>This is the {@link org.xml.sax.XMLReader XMLReader} from which
104      * this filter will obtain its events and to which it will pass its
105      * configuration requests. The parent may itself be another filter.</p>
106      *
107      * <p>If there is no parent reader set, any attempt to parse
108      * or to set or get a feature or property will fail.</p>
109      *
110      * @param parent The parent XML reader.
111      * @see #getParent
112      */
113     public void setParent (XMLReader parent)
114     {
115     this.parent = parent;
116     }
117
118
119     /**
120      * Get the parent reader.
121      *
122      * @return The parent XML reader, or null if none is set.
123      * @see #setParent
124      */
125     public XMLReader getParent ()
126     {
127     return parent;
128     }
129
130
131 
132     ////////////////////////////////////////////////////////////////////
133 // Implementation of org.xml.sax.XMLReader.
134 ////////////////////////////////////////////////////////////////////
135
136
137     /**
138      * Set the value of a feature.
139      *
140      * <p>This will always fail if the parent is null.</p>
141      *
142      * @param name The feature name.
143      * @param value The requested feature value.
144      * @exception org.xml.sax.SAXNotRecognizedException If the feature
145      * value can't be assigned or retrieved from the parent.
146      * @exception org.xml.sax.SAXNotSupportedException When the
147      * parent recognizes the feature name but
148      * cannot set the requested value.
149      */
150     public void setFeature (String name, boolean value)
151     throws SAXNotRecognizedException , SAXNotSupportedException
152     {
153     if (parent != null) {
154         parent.setFeature(name, value);
155     } else {
156         throw new SAXNotRecognizedException ("Feature: " + name);
157     }
158     }
159
160
161     /**
162      * Look up the value of a feature.
163      *
164      * <p>This will always fail if the parent is null.</p>
165      *
166      * @param name The feature name.
167      * @return The current value of the feature.
168      * @exception org.xml.sax.SAXNotRecognizedException If the feature
169      * value can't be assigned or retrieved from the parent.
170      * @exception org.xml.sax.SAXNotSupportedException When the
171      * parent recognizes the feature name but
172      * cannot determine its value at this time.
173      */
174     public boolean getFeature (String name)
175     throws SAXNotRecognizedException , SAXNotSupportedException
176     {
177     if (parent != null) {
178         return parent.getFeature(name);
179     } else {
180         throw new SAXNotRecognizedException ("Feature: " + name);
181     }
182     }
183
184
185     /**
186      * Set the value of a property.
187      *
188      * <p>This will always fail if the parent is null.</p>
189      *
190      * @param name The property name.
191      * @param value The requested property value.
192      * @exception org.xml.sax.SAXNotRecognizedException If the property
193      * value can't be assigned or retrieved from the parent.
194      * @exception org.xml.sax.SAXNotSupportedException When the
195      * parent recognizes the property name but
196      * cannot set the requested value.
197      */
198     public void setProperty (String name, Object value)
199     throws SAXNotRecognizedException , SAXNotSupportedException
200     {
201     if (parent != null) {
202         parent.setProperty(name, value);
203     } else {
204         throw new SAXNotRecognizedException ("Property: " + name);
205     }
206     }
207
208
209     /**
210      * Look up the value of a property.
211      *
212      * @param name The property name.
213      * @return The current value of the property.
214      * @exception org.xml.sax.SAXNotRecognizedException If the property
215      * value can't be assigned or retrieved from the parent.
216      * @exception org.xml.sax.SAXNotSupportedException When the
217      * parent recognizes the property name but
218      * cannot determine its value at this time.
219      */
220     public Object getProperty (String name)
221     throws SAXNotRecognizedException , SAXNotSupportedException
222     {
223     if (parent != null) {
224         return parent.getProperty(name);
225     } else {
226         throw new SAXNotRecognizedException ("Property: " + name);
227     }
228     }
229
230
231     /**
232      * Set the entity resolver.
233      *
234      * @param resolver The new entity resolver.
235      */
236     public void setEntityResolver (EntityResolver resolver)
237     {
238     entityResolver = resolver;
239     }
240
241
242     /**
243      * Get the current entity resolver.
244      *
245      * @return The current entity resolver, or null if none was set.
246      */
247     public EntityResolver getEntityResolver ()
248     {
249     return entityResolver;
250     }
251
252
253     /**
254      * Set the DTD event handler.
255      *
256      * @param handler the new DTD handler
257      */
258     public void setDTDHandler (DTDHandler handler)
259     {
260     dtdHandler = handler;
261     }
262
263
264     /**
265      * Get the current DTD event handler.
266      *
267      * @return The current DTD handler, or null if none was set.
268      */
269     public DTDHandler getDTDHandler ()
270     {
271     return dtdHandler;
272     }
273
274
275     /**
276      * Set the content event handler.
277      *
278      * @param handler the new content handler
279      */
280     public void setContentHandler (ContentHandler handler)
281     {
282     contentHandler = handler;
283     }
284
285
286     /**
287      * Get the content event handler.
288      *
289      * @return The current content handler, or null if none was set.
290      */
291     public ContentHandler getContentHandler ()
292     {
293     return contentHandler;
294     }
295
296
297     /**
298      * Set the error event handler.
299      *
300      * @param handler the new error handler
301      */
302     public void setErrorHandler (ErrorHandler handler)
303     {
304     errorHandler = handler;
305     }
306
307
308     /**
309      * Get the current error event handler.
310      *
311      * @return The current error handler, or null if none was set.
312      */
313     public ErrorHandler getErrorHandler ()
314     {
315     return errorHandler;
316     }
317
318
319     /**
320      * Parse a document.
321      *
322      * @param input The input source for the document entity.
323      * @exception org.xml.sax.SAXException Any SAX exception, possibly
324      * wrapping another exception.
325      * @exception java.io.IOException An IO exception from the parser,
326      * possibly from a byte stream or character stream
327      * supplied by the application.
328      */
329     public void parse (InputSource input)
330     throws SAXException , IOException
331     {
332     setupParse();
333     parent.parse(input);
334     }
335
336
337     /**
338      * Parse a document.
339      *
340      * @param systemId The system identifier as a fully-qualified URI.
341      * @exception org.xml.sax.SAXException Any SAX exception, possibly
342      * wrapping another exception.
343      * @exception java.io.IOException An IO exception from the parser,
344      * possibly from a byte stream or character stream
345      * supplied by the application.
346      */
347     public void parse (String systemId)
348     throws SAXException , IOException
349     {
350     parse(new InputSource (systemId));
351     }
352
353
354 
355     ////////////////////////////////////////////////////////////////////
356 // Implementation of org.xml.sax.EntityResolver.
357 ////////////////////////////////////////////////////////////////////
358
359
360     /**
361      * Filter an external entity resolution.
362      *
363      * @param publicId The entity's public identifier, or null.
364      * @param systemId The entity's system identifier.
365      * @return A new InputSource or null for the default.
366      * @exception org.xml.sax.SAXException The client may throw
367      * an exception during processing.
368      * @exception java.io.IOException The client may throw an
369      * I/O-related exception while obtaining the
370      * new InputSource.
371      */
372     public InputSource resolveEntity (String publicId, String systemId)
373     throws SAXException , IOException
374     {
375     if (entityResolver != null) {
376         return entityResolver.resolveEntity(publicId, systemId);
377     } else {
378         return null;
379     }
380     }
381
382
383 
384     ////////////////////////////////////////////////////////////////////
385 // Implementation of org.xml.sax.DTDHandler.
386 ////////////////////////////////////////////////////////////////////
387
388     
389     /**
390      * Filter a notation declaration event.
391      *
392      * @param name The notation name.
393      * @param publicId The notation's public identifier, or null.
394      * @param systemId The notation's system identifier, or null.
395      * @exception org.xml.sax.SAXException The client may throw
396      * an exception during processing.
397      */
398     public void notationDecl (String name, String publicId, String systemId)
399     throws SAXException
400     {
401     if (dtdHandler != null) {
402         dtdHandler.notationDecl(name, publicId, systemId);
403     }
404     }
405
406     
407     /**
408      * Filter an unparsed entity declaration event.
409      *
410      * @param name The entity name.
411      * @param publicId The entity's public identifier, or null.
412      * @param systemId The entity's system identifier, or null.
413      * @param notationName The name of the associated notation.
414      * @exception org.xml.sax.SAXException The client may throw
415      * an exception during processing.
416      */
417     public void unparsedEntityDecl (String name, String publicId,
418                     String systemId, String notationName)
419     throws SAXException
420     {
421     if (dtdHandler != null) {
422         dtdHandler.unparsedEntityDecl(name, publicId, systemId,
423                       notationName);
424     }
425     }
426
427
428 
429     ////////////////////////////////////////////////////////////////////
430 // Implementation of org.xml.sax.ContentHandler.
431 ////////////////////////////////////////////////////////////////////
432
433
434     /**
435      * Filter a new document locator event.
436      *
437      * @param locator The document locator.
438      */
439     public void setDocumentLocator (Locator locator)
440     {
441     this.locator = locator;
442     if (contentHandler != null) {
443         contentHandler.setDocumentLocator(locator);
444     }
445     }
446
447
448     /**
449      * Filter a start document event.
450      *
451      * @exception org.xml.sax.SAXException The client may throw
452      * an exception during processing.
453      */
454     public void startDocument ()
455     throws SAXException
456     {
457     if (contentHandler != null) {
458         contentHandler.startDocument();
459     }
460     }
461
462
463     /**
464      * Filter an end document event.
465      *
466      * @exception org.xml.sax.SAXException The client may throw
467      * an exception during processing.
468      */
469     public void endDocument ()
470     throws SAXException
471     {
472     if (contentHandler != null) {
473         contentHandler.endDocument();
474     }
475     }
476
477
478     /**
479      * Filter a start Namespace prefix mapping event.
480      *
481      * @param prefix The Namespace prefix.
482      * @param uri The Namespace URI.
483      * @exception org.xml.sax.SAXException The client may throw
484      * an exception during processing.
485      */
486     public void startPrefixMapping (String prefix, String uri)
487     throws SAXException
488     {
489     if (contentHandler != null) {
490         contentHandler.startPrefixMapping(prefix, uri);
491     }
492     }
493
494
495     /**
496      * Filter an end Namespace prefix mapping event.
497      *
498      * @param prefix The Namespace prefix.
499      * @exception org.xml.sax.SAXException The client may throw
500      * an exception during processing.
501      */
502     public void endPrefixMapping (String prefix)
503     throws SAXException
504     {
505     if (contentHandler != null) {
506         contentHandler.endPrefixMapping(prefix);
507     }
508     }
509
510
511     /**
512      * Filter a start element event.
513      *
514      * @param uri The element's Namespace URI, or the empty string.
515      * @param localName The element's local name, or the empty string.
516      * @param qName The element's qualified (prefixed) name, or the empty
517      * string.
518      * @param atts The element's attributes.
519      * @exception org.xml.sax.SAXException The client may throw
520      * an exception during processing.
521      */
522     public void startElement (String uri, String localName, String qName,
523                   Attributes atts)
524     throws SAXException
525     {
526     if (contentHandler != null) {
527         contentHandler.startElement(uri, localName, qName, atts);
528     }
529     }
530
531
532     /**
533      * Filter an end element event.
534      *
535      * @param uri The element's Namespace URI, or the empty string.
536      * @param localName The element's local name, or the empty string.
537      * @param qName The element's qualified (prefixed) name, or the empty
538      * string.
539      * @exception org.xml.sax.SAXException The client may throw
540      * an exception during processing.
541      */
542     public void endElement (String uri, String localName, String qName)
543     throws SAXException
544     {
545     if (contentHandler != null) {
546         contentHandler.endElement(uri, localName, qName);
547     }
548     }
549
550
551     /**
552      * Filter a character data event.
553      *
554      * @param ch An array of characters.
555      * @param start The starting position in the array.
556      * @param length The number of characters to use from the array.
557      * @exception org.xml.sax.SAXException The client may throw
558      * an exception during processing.
559      */
560     public void characters (char ch[], int start, int length)
561     throws SAXException
562     {
563     if (contentHandler != null) {
564         contentHandler.characters(ch, start, length);
565     }
566     }
567
568
569     /**
570      * Filter an ignorable whitespace event.
571      *
572      * @param ch An array of characters.
573      * @param start The starting position in the array.
574      * @param length The number of characters to use from the array.
575      * @exception org.xml.sax.SAXException The client may throw
576      * an exception during processing.
577      */
578     public void ignorableWhitespace (char ch[], int start, int length)
579     throws SAXException
580     {
581     if (contentHandler != null) {
582         contentHandler.ignorableWhitespace(ch, start, length);
583     }
584     }
585
586
587     /**
588      * Filter a processing instruction event.
589      *
590      * @param target The processing instruction target.
591      * @param data The text following the target.
592      * @exception org.xml.sax.SAXException The client may throw
593      * an exception during processing.
594      */
595     public void processingInstruction (String target, String data)
596     throws SAXException
597     {
598     if (contentHandler != null) {
599         contentHandler.processingInstruction(target, data);
600     }
601     }
602
603
604     /**
605      * Filter a skipped entity event.
606      *
607      * @param name The name of the skipped entity.
608      * @exception org.xml.sax.SAXException The client may throw
609      * an exception during processing.
610      */
611     public void skippedEntity (String name)
612     throws SAXException
613     {
614     if (contentHandler != null) {
615         contentHandler.skippedEntity(name);
616     }
617     }
618
619
620 
621     ////////////////////////////////////////////////////////////////////
622 // Implementation of org.xml.sax.ErrorHandler.
623 ////////////////////////////////////////////////////////////////////
624
625
626     /**
627      * Filter a warning event.
628      *
629      * @param e The warning as an exception.
630      * @exception org.xml.sax.SAXException The client may throw
631      * an exception during processing.
632      */
633     public void warning (SAXParseException e)
634     throws SAXException
635     {
636     if (errorHandler != null) {
637         errorHandler.warning(e);
638     }
639     }
640
641
642     /**
643      * Filter an error event.
644      *
645      * @param e The error as an exception.
646      * @exception org.xml.sax.SAXException The client may throw
647      * an exception during processing.
648      */
649     public void error (SAXParseException e)
650     throws SAXException
651     {
652     if (errorHandler != null) {
653         errorHandler.error(e);
654     }
655     }
656
657
658     /**
659      * Filter a fatal error event.
660      *
661      * @param e The error as an exception.
662      * @exception org.xml.sax.SAXException The client may throw
663      * an exception during processing.
664      */
665     public void fatalError (SAXParseException e)
666     throws SAXException
667     {
668     if (errorHandler != null) {
669         errorHandler.fatalError(e);
670     }
671     }
672
673
674 
675     ////////////////////////////////////////////////////////////////////
676 // Internal methods.
677 ////////////////////////////////////////////////////////////////////
678
679
680     /**
681      * Set up before a parse.
682      *
683      * <p>Before every parse, check whether the parent is
684      * non-null, and re-register the filter for all of the
685      * events.</p>
686      */
687     private void setupParse ()
688     {
689     if (parent == null) {
690         throw new NullPointerException ("No parent for filter");
691     }
692     parent.setEntityResolver(this);
693     parent.setDTDHandler(this);
694     parent.setContentHandler(this);
695     parent.setErrorHandler(this);
696     }
697
698
699 
700     ////////////////////////////////////////////////////////////////////
701 // Internal state.
702 ////////////////////////////////////////////////////////////////////
703
704     private XMLReader parent = null;
705     private Locator locator = null;
706     private EntityResolver entityResolver = null;
707     private DTDHandler dtdHandler = null;
708     private ContentHandler contentHandler = null;
709     private ErrorHandler errorHandler = null;
710
711 }
712
713 // end of XMLFilterImpl.java
714

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