001    /*
002     * $Id: Unmarshaller.java,v 1.28 2003/02/28 21:44:24 ryans Exp $
003     *
004     * Copyright 2001 Sun Microsystems, Inc. All Rights Reserved.
005     * 
006     * This software is the proprietary information of Sun Microsystems, Inc.  
007     * Use is subject to license terms.
008     * 
009     */
010    
011    package javax.xml.bind;
012    
013    /**
014     * The <tt>Unmarshaller</tt> class governs the process of deserializing XML 
015     * data into newly created Java content trees, optionally validating the XML 
016     * data as it is unmarshalled.  It provides the basic unmarshalling methods:
017     *    
018     * <p>
019     * Unmarshalling from a File:
020     * <blockquote>
021     *    <pre>
022     *       JAXBContext jc = JAXBContext.newInstance( "com.acme.foo" );
023     *       Unmarshaller u = jc.createUnmarshaller();
024     *       Object o = u.unmarshal( new File( "nosferatu.xml" ) );
025     *    </pre>
026     * </blockquote>
027     *
028     *  
029     * <p>
030     * Unmarshalling from an InputStream:
031     * <blockquote>
032     *    <pre>
033     *       InputStream is = new FileInputStream( "nosferatu.xml" );
034     *       JAXBContext jc = JAXBContext.newInstance( "com.acme.foo" );
035     *       Unmarshaller u = jc.createUnmarshaller();
036     *       Object o = u.unmarshal( is );
037     *    </pre>
038     * </blockquote>
039     *
040     * <p>
041     * Unmarshalling from a URL:
042     * <blockquote>
043     *    <pre>
044     *       JAXBContext jc = JAXBContext.newInstance( "com.acme.foo" );
045     *       Unmarshaller u = jc.createUnmarshaller();
046     *       URL url = new URL( "http://beaker.east/nosferatu.xml" );
047     *       Object o = u.unmarshal( url );
048     *    </pre>
049     * </blockquote>
050     *
051     * <p>
052     * Unmarshalling from a StringBuffer using a 
053     * <tt>javax.xml.transform.stream.StreamSource</tt>:
054     * <blockquote>
055     *    <pre>
056     *       JAXBContext jc = JAXBContext.newInstance( "com.acme.foo" );
057     *       Unmarshaller u = jc.createUnmarshaller();
058     *       StringBuffer xmlStr = new StringBuffer( "&lt;?xml version=&quot;1.0&quot;?&gt;..." );
059     *       Object o = u.unmarshal( new StreamSource( new StringReader( xmlStr.toString() ) ) );
060     *    </pre>
061     * </blockquote>
062     *
063     * <p>
064     * Unmarshalling from a <tt>org.w3c.dom.Node</tt>:
065     * <blockquote>
066     *    <pre>
067     *       JAXBContext jc = JAXBContext.newInstance( "com.acme.foo" );
068     *       Unmarshaller u = jc.createUnmarshaller();
069     * 
070     *       DocumentBuilderFactory dbf = DocumentBuilderFactory.newInstance();
071     *       dbf.setNamespaceAware(true);
072     *       DocumentBuilder db = dbf.newDocumentBuilder();
073     *       Document doc = db.parse(new File( "nosferatu.xml"));
074    
075     *       Object o = u.unmarshal( doc );
076     *    </pre>
077     * </blockquote>
078     * 
079     * <p>
080     * Unmarshalling from a <tt>javax.xml.transform.sax.SAXSource</tt> using a
081     * client specified validating SAX2.0 parser:
082     * <blockquote>
083     *    <pre>
084     *       // configure a validating SAX2.0 parser (Xerces2)
085     *       static final String JAXP_SCHEMA_LANGUAGE =
086     *           "http://java.sun.com/xml/jaxp/properties/schemaLanguage";
087     *       static final String JAXP_SCHEMA_LOCATION =
088     *           "http://java.sun.com/xml/jaxp/properties/schemaSource";
089     *       static final String W3C_XML_SCHEMA =
090     *           "http://www.w3.org/2001/XMLSchema";
091     *
092     *       System.setProperty( "javax.xml.parsers.SAXParserFactory",
093     *                           "org.apache.xerces.jaxp.SAXParserFactoryImpl" );
094     *
095     *       SAXParserFactory spf = SAXParserFactory.newInstance();
096     *       spf.setNamespaceAware(true);
097     *       spf.setValidating(true);
098     *       SAXParser saxParser = spf.newSAXParser();
099     *       
100     *       try {
101     *           saxParser.setProperty(JAXP_SCHEMA_LANGUAGE, W3C_XML_SCHEMA);
102     *           saxParser.setProperty(JAXP_SCHEMA_LOCATION, "http://....");
103     *       } catch (SAXNotRecognizedException x) {
104     *           // exception handling omitted
105     *       }
106     *
107     *       XMLReader xmlReader = saxParser.getXMLReader();
108     *       SAXSource source = 
109     *           new SAXSource( xmlReader, new InputSource( "http://..." ) );
110     *
111     *       // Setup JAXB to unmarshal
112     *       JAXBContext jc = JAXBContext.newInstance( "com.acme.foo" );
113     *       Unmarshaller u = jc.createUnmarshaller();
114     *       ValidationEventCollector vec = new ValidationEventCollector();
115     *       u.setEventHandler( vec );
116     *       
117     *       // turn off the JAXB provider's default validation mechanism to 
118     *       // avoid duplicate validation
119     *       u.setValidating( false )
120     *
121     *       // unmarshal
122     *       Object o = u.unmarshal( source );
123     *
124     *       // check for events
125     *       if( vec.hasEvents() ) {
126     *          // iterate over events
127     *       }
128     *    </pre>
129     * </blockquote>
130     *
131     * <p>
132     * <a name="unmarshalEx"></a>
133     * <b>Unmarshalling XML Data</b><br>
134     * <blockquote>
135     * The <tt>JAXBContext</tt> object used to create this <tt>Unmarshaller</tt>
136     * was initialized with a <tt>contextPath</tt> which determines the schema
137     * derived content available to the <tt>Marshaller</tt>, <tt>Unmarshaller</tt>,
138     * and <tt>Validator</tt> objects it produces.  If the <tt>JAXBContext</tt> 
139     * object that was used to create this <tt>Unmarshaller</tt> does not have 
140     * enough information to know how to unmarshal the XML content from the 
141     * specified source, then the unmarshal operation will abort immediately by 
142     * throwing a {@link UnmarshalException UnmarshalException}.
143     * </blockquote>
144     *
145     * <p>
146     * <b>Support for SAX2.0 Compliant Parsers</b><br>
147     * <blockquote>
148     * A client application has the ability to select the SAX2.0 compliant parser
149     * of their choice.  If a SAX parser is not selected, then the JAXB Provider's
150     * default parser will be used.  Eventhough the JAXB Provider's default parser
151     * is not required to be SAX2.0 compliant, all providers are required to allow
152     * a client application to specify their own SAX2.0 parser.  Some providers may
153     * require the client application to specify the SAX2.0 parser at schema compile
154     * time. See {@link #unmarshal(javax.xml.transform.Source) unmarshal(Source)} 
155     * for more detail.
156     * </blockquote>
157     *
158     * <p>
159     * <b>Validation and Well-Formedness</b><br>
160     * <blockquote>
161     * <p>
162     * A client application can enable or disable the provider's default validation
163     * mechanism via the <tt>setValidating</tt> API.  Sophisticated clients can 
164     * specify their own validating SAX 2.0 compliant parser and bypass the 
165     * provider's default validation mechanism using the 
166     * {@link #unmarshal(javax.xml.transform.Source) unmarshal(Source)}  API.
167     * 
168     * <p>
169     * For a more detailed definition of how validation errors and warnings are
170     * handled, see the {@link Validator Validator} javadoc.
171     * </blockquote>
172     *
173     * <p>
174     * <a name="supportedProps"></a>
175     * <b>Supported Properties</b><br>
176     * <blockquote>
177     * <p>
178     * There currently are not any properties required to be supported by all 
179     * JAXB Providers on Unmarshaller.  However, some providers may support 
180     * their own set of provider specific properties.
181     * </blockquote>
182     * 
183     * 
184     * @author <ul><li>Ryan Shoemaker, Sun Microsystems, Inc.</li><li>Kohsuke Kawaguchi, Sun Microsystems, Inc.</li><li>Joe Fialli, Sun Microsystems, Inc.</li></ul>
185     * @version $Revision: 1.28 $ $Date: 2003/02/28 21:44:24 $
186     * @see JAXBContext
187     * @see Marshaller
188     * @see Validator
189     * @since JAXB1.0
190     */
191    public interface Unmarshaller {
192        
193        /**
194         * Unmarshal XML data from the specified file and return the resulting
195         * content tree.
196         *
197         * @param f the file to unmarshal XML data from
198         * @return the newly created root object of the java content tree 
199         *
200         * @throws JAXBException 
201         *     If any unexpected errors occur while unmarshalling
202         * @throws UnmarshalException
203         *     If the {@link ValidationEventHandler ValidationEventHandler}
204         *     returns false from its <tt>handleEvent</tt> method or the 
205         *     <tt>Unmarshaller</tt> is unable to perform the XML to Java
206         *     binding.  See <a href="#unmarshalEx">Unmarshalling XML Data</a>
207         * @throws IllegalArgumentException
208         *      If the file parameter is null
209         */
210        public Object unmarshal( java.io.File f ) throws JAXBException;
211        
212        /**
213         * Unmarshal XML data from the specified InputStream and return the 
214         * resulting content tree.  Validation event location information may
215         * be incomplete when using this form of the unmarshal API.
216         *
217         * @param is the InputStream to unmarshal XML data from
218         * @return the newly created root object of the java content tree 
219         *
220         * @throws JAXBException 
221         *     If any unexpected errors occur while unmarshalling
222         * @throws UnmarshalException
223         *     If the {@link ValidationEventHandler ValidationEventHandler}
224         *     returns false from its <tt>handleEvent</tt> method or the 
225         *     <tt>Unmarshaller</tt> is unable to perform the XML to Java
226         *     binding.  See <a href="#unmarshalEx">Unmarshalling XML Data</a>
227         * @throws IllegalArgumentException
228         *      If the InputStream parameter is null
229         */
230        public Object unmarshal( java.io.InputStream is ) throws JAXBException;
231    
232        /**
233         * Unmarshal XML data from the specified URL and return the resulting
234         * content tree.
235         *
236         * @param url the url to unmarshal XML data from
237         * @return the newly created root object of the java content tree 
238         *
239         * @throws JAXBException 
240         *     If any unexpected errors occur while unmarshalling
241         * @throws UnmarshalException
242         *     If the {@link ValidationEventHandler ValidationEventHandler}
243         *     returns false from its <tt>handleEvent</tt> method or the 
244         *     <tt>Unmarshaller</tt> is unable to perform the XML to Java
245         *     binding.  See <a href="#unmarshalEx">Unmarshalling XML Data</a>
246         * @throws IllegalArgumentException
247         *      If the URL parameter is null
248         */
249        public Object unmarshal( java.net.URL url ) throws JAXBException;
250        
251        /**
252         * Unmarshal XML data from the specified SAX InputSource and return the
253         * resulting content tree.
254         *
255         * @param source the input source to unmarshal XML data from
256         * @return the newly created root object of the java content tree 
257         *
258         * @throws JAXBException 
259         *     If any unexpected errors occur while unmarshalling
260         * @throws UnmarshalException
261         *     If the {@link ValidationEventHandler ValidationEventHandler}
262         *     returns false from its <tt>handleEvent</tt> method or the 
263         *     <tt>Unmarshaller</tt> is unable to perform the XML to Java
264         *     binding.  See <a href="#unmarshalEx">Unmarshalling XML Data</a>
265         * @throws IllegalArgumentException
266         *      If the InputSource parameter is null
267         */
268        public Object unmarshal( org.xml.sax.InputSource source ) throws JAXBException;
269        
270        /**
271         * Unmarshal XML data from the specified DOM tree and return the resulting
272         * content tree.
273         *
274         * @param node
275         *      the document/element to unmarshal XML data from.
276         *      The caller must support at least Document and Element.
277         * @return the newly created root object of the java content tree 
278         *
279         * @throws JAXBException 
280         *     If any unexpected errors occur while unmarshalling
281         * @throws UnmarshalException
282         *     If the {@link ValidationEventHandler ValidationEventHandler}
283         *     returns false from its <tt>handleEvent</tt> method or the 
284         *     <tt>Unmarshaller</tt> is unable to perform the XML to Java
285         *     binding.  See <a href="#unmarshalEx">Unmarshalling XML Data</a>
286         * @throws IllegalArgumentException
287         *      If the Node parameter is null
288         */
289        public Object unmarshal( org.w3c.dom.Node node ) throws JAXBException;
290        
291        /**
292         * Unmarshal XML data from the specified XML Source and return the 
293         * resulting content tree.  
294         * <p>
295         * <b>SAX 2.0 Parser Pluggability</b>
296         * <p>
297         * A client application can choose not to use the default parser mechanism
298         * supplied with their JAXB provider.  Any SAX 2.0 compliant parser can be
299         * substituted for the JAXB provider's default mechanism.  To do so, the
300         * client application must properly configure a <tt>SAXSource</tt> containing 
301         * an <tt>XMLReader</tt> implemented by the SAX 2.0 parser provider.  If the
302         * <tt>XMLReader</tt> has an <tt>org.xml.sax.ErrorHandler</tt> registered
303         * on it, it will be replaced by the JAXB Provider so that validation errors
304         * can be reported via the <tt>ValidationEventHandler</tt> mechanism of
305         * JAXB.  If the <tt>SAXSource</tt> does not contain an <tt>XMLReader</tt>, 
306         * then the JAXB provider's default parser mechanism will be used.
307         * <p>
308         * This parser replacement mechanism can also be used to replace the JAXB
309         * provider's unmarshal-time validation engine.  The client application 
310         * must properly configure their SAX 2.0 compliant parser to perform
311         * validation (as shown in the example above).  Any <tt>SAXParserExceptions
312         * </tt> encountered by the parser during the unmarshal operation will be 
313         * processed by the JAXB provider and converted into JAXB 
314         * <tt>ValidationEvent</tt> objects which will be reported back to the 
315         * client via the <tt>ValidationEventHandler</tt> registered with the 
316         * <tt>Unmarshaller</tt>.  <i>Note:</i> specifying a substitute validating 
317         * SAX 2.0 parser for unmarshalling does not necessarily replace the 
318         * validation engine used by the JAXB provider for performing on-demand 
319         * validation.
320         * <p>
321         * The only way for a client application to specify an alternate parser
322         * mechanism to be used during unmarshal is via the 
323         * <tt>unmarshal(SAXSource)</tt> API.  All other forms of the unmarshal 
324         * method (File, URL, Node, etc) will use the JAXB provider's default 
325         * parser and validator mechanisms.
326         *
327         * @param source the XML Source to unmarshal XML data from (providers are
328         *        only required to support SAXSource, DOMSource, and StreamSource)
329         * @return the newly created root object of the java content tree
330         *
331         * @throws JAXBException 
332         *     If any unexpected errors occur while unmarshalling
333         * @throws UnmarshalException
334         *     If the {@link ValidationEventHandler ValidationEventHandler}
335         *     returns false from its <tt>handleEvent</tt> method or the 
336         *     <tt>Unmarshaller</tt> is unable to perform the XML to Java
337         *     binding.  See <a href="#unmarshalEx">Unmarshalling XML Data</a>
338         * @throws IllegalArgumentException
339         *      If the Source parameter is null
340         */
341        public Object unmarshal( javax.xml.transform.Source source )
342            throws JAXBException;
343         
344        /**
345         * Get an unmarshaller handler object that can be used as a component in
346         * an XML pipeline.
347         * 
348         * <p>
349         * The JAXB Provider can return the same handler object for multiple 
350         * invocations of this method. In other words, this method does not 
351         * necessarily create a new instance of <tt>UnmarshallerHandler</tt>. If the 
352         * application needs to use more than one <tt>UnmarshallerHandler</tt>, it 
353         * should create more than one <tt>Unmarshaller</tt>.
354         *
355         * @return the unmarshaller handler object
356         * @see UnmarshallerHandler
357         */
358        public UnmarshallerHandler getUnmarshallerHandler();
359        
360        /**
361         * Specifies whether or not the default validation mechanism of the
362         * <tt>Unmarshaller</tt> should validate during unmarshal operations.  
363         * By default, the <tt>Unmarshaller</tt> does not validate.
364         * <p>
365         * This method may only be invoked before or after calling one of the
366         * unmarshal methods.
367         * <p>
368         * This method only controls the JAXB Provider's default unmarshal-time
369         * validation mechanism - it has no impact on clients that specify their 
370         * own validating SAX 2.0 compliant parser.  Clients that specify their
371         * own unmarshal-time validation mechanism may wish to turn off the JAXB
372         * Provider's default validation mechanism via this API to avoid "double
373         * validation".
374         * 
375         * @param validating true if the Unmarshaller should validate during 
376         *        unmarshal, false otherwise
377         * @throws JAXBException if an error occurred while enabling or disabling
378                   validation at unmarshal time
379         */
380        public void setValidating( boolean validating ) 
381            throws JAXBException;
382        
383        /**
384         * Indicates whether or not the <tt>Unmarshaller</tt> is configured to 
385         * validate during unmarshal operations.
386         *
387         * <p>
388         * This API returns the state of the JAXB Provider's default unmarshal-time
389         * validation mechanism. 
390         *
391         * @return true if the Unmarshaller is configured to validate during 
392         *         unmarshal operations, false otherwise
393         * @throws JAXBException if an error occurs while retrieving the validating
394         *         flag
395         */
396        public boolean isValidating() 
397            throws JAXBException;
398        
399        /**
400         * Allow an application to register a <tt>ValidationEventHandler</tt>.
401         * <p>
402         * The <tt>ValidationEventHandler</tt> will be called by the JAXB Provider 
403         * if any validation errors are encountered during calls to any of the 
404         * unmarshal methods.  If the client application does not register a 
405         * <tt>ValidationEventHandler</tt> before invoking the unmarshal methods, 
406         * then <tt>ValidationEvents</tt> will be handled by the default event 
407         * handler which will terminate the unmarshal operation after the first 
408         * error or fatal error is encountered.
409         * <p>
410         * Calling this method with a null parameter will cause the Unmarshaller
411         * to revert back to the default vefault event handler.
412         *
413         * @param handler the validation event handler
414         * @throws JAXBException if an error was encountered while setting the
415         *         event handler
416         */
417        public void setEventHandler( ValidationEventHandler handler )
418            throws JAXBException;
419    
420        /**
421         * Return the current event handler or the default event handler if one
422         * hasn't been set.
423         *
424         * @return the current ValidationEventHandler or the default event handler
425         *         if it hasn't been set
426         * @throws JAXBException if an error was encountered while getting the 
427         *         current event handler
428         */
429        public ValidationEventHandler getEventHandler()
430            throws JAXBException;
431    
432        /**
433         * Set the particular property in the underlying implementation of 
434         * <tt>Unarshaller</tt>.  This method can only be used to set one of
435         * the standard JAXB defined properties above or a provider specific
436         * property.  Attempting to set an undefined property will result in
437         * a PropertyException being thrown.  See <a href="#supportedProps">
438         * Supported Properties</a>.
439         *
440         * @param name the name of the property to be set. This value can either
441         *              be specified using one of the constant fields or a user 
442         *              supplied string.
443         * @param value the value of the property to be set
444         *
445         * @throws PropertyException when there is an error processing the given
446         *                            property or value
447         * @throws IllegalArgumentException
448         *      If the name parameter is null
449         */
450        public void setProperty( String name, Object value ) 
451            throws PropertyException;
452        
453        /**
454         * Get the particular property in the underlying implementation of 
455         * <tt>Unmarshaller</tt>.  This method can only be used to get one of
456         * the standard JAXB defined properties above or a provider specific
457         * property.  Attempting to get an undefined property will result in
458         * a PropertyException being thrown.  See <a href="#supportedProps">
459         * Supported Properties</a>.
460         *
461         * @param name the name of the property to retrieve
462         * @return the value of the requested property
463         *
464         * @throws PropertyException
465         *      when there is an error retrieving the given property or value
466         *      property name
467         * @throws IllegalArgumentException
468         *      If the name parameter is null
469         */
470        public Object getProperty( String name ) throws PropertyException;
471        
472            
473    }