View Javadoc
1   /*
2    * Copyright (c) 2000, 2005, 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 javax.xml.transform;
27  
28  import java.util.Properties;
29  
30  /**
31   * An instance of this abstract class can transform a
32   * source tree into a result tree.
33   *
34   * <p>An instance of this class can be obtained with the
35   * {@link TransformerFactory#newTransformer TransformerFactory.newTransformer}
36   * method. This instance may then be used to process XML from a
37   * variety of sources and write the transformation output to a
38   * variety of sinks.</p>
39   *
40   * <p>An object of this class may not be used in multiple threads
41   * running concurrently.  Different Transformers may be used
42   * concurrently by different threads.</p>
43   *
44   * <p>A <code>Transformer</code> may be used multiple times.  Parameters and
45   * output properties are preserved across transformations.</p>
46   *
47   * @author <a href="Jeff.Suttor@Sun.com">Jeff Suttor</a>
48   */
49  public abstract class Transformer {
50  
51      /**
52       * Default constructor is protected on purpose.
53       */
54      protected Transformer() { }
55  
56          /**
57           * <p>Reset this <code>Transformer</code> to its original configuration.</p>
58           *
59           * <p><code>Transformer</code> is reset to the same state as when it was created with
60           * {@link TransformerFactory#newTransformer()},
61           * {@link TransformerFactory#newTransformer(Source source)} or
62           * {@link Templates#newTransformer()}.
63           * <code>reset()</code> is designed to allow the reuse of existing <code>Transformer</code>s
64           * thus saving resources associated with the creation of new <code>Transformer</code>s.</p>
65           *
66           * <p>The reset <code>Transformer</code> is not guaranteed to have the same {@link URIResolver}
67           * or {@link ErrorListener} <code>Object</code>s, e.g. {@link Object#equals(Object obj)}.
68           * It is guaranteed to have a functionally equal <code>URIResolver</code>
69           * and <code>ErrorListener</code>.</p>
70       *
71       * @throws UnsupportedOperationException When implementation does not
72       *   override this method.
73           *
74           * @since 1.5
75           */
76          public void reset() {
77  
78                  // implementors should override this method
79                  throw new UnsupportedOperationException(
80                          "This Transformer, \"" + this.getClass().getName() + "\", does not support the reset functionality."
81                          + "  Specification \"" + this.getClass().getPackage().getSpecificationTitle() + "\""
82                          + " version \"" + this.getClass().getPackage().getSpecificationVersion() + "\""
83                          );
84          }
85  
86      /**
87       * <p>Transform the XML <code>Source</code> to a <code>Result</code>.
88       * Specific transformation behavior is determined by the settings of the
89       * <code>TransformerFactory</code> in effect when the
90       * <code>Transformer</code> was instantiated and any modifications made to
91       * the <code>Transformer</code> instance.</p>
92       *
93       * <p>An empty <code>Source</code> is represented as an empty document
94       * as constructed by {@link javax.xml.parsers.DocumentBuilder#newDocument()}.
95       * The result of transforming an empty <code>Source</code> depends on
96       * the transformation behavior; it is not always an empty
97       * <code>Result</code>.</p>
98       *
99       * @param xmlSource The XML input to transform.
100      * @param outputTarget The <code>Result</code> of transforming the
101      *   <code>xmlSource</code>.
102      *
103      * @throws TransformerException If an unrecoverable error occurs
104      *   during the course of the transformation.
105      */
106     public abstract void transform(Source xmlSource, Result outputTarget)
107         throws TransformerException;
108 
109     /**
110      * Add a parameter for the transformation.
111      *
112      * <p>Pass a qualified name as a two-part string, the namespace URI
113      * enclosed in curly braces ({}), followed by the local name. If the
114      * name has a null URL, the String only contain the local name. An
115      * application can safely check for a non-null URI by testing to see if the
116      * first character of the name is a '{' character.</p>
117      * <p>For example, if a URI and local name were obtained from an element
118      * defined with &lt;xyz:foo
119      * xmlns:xyz="http://xyz.foo.com/yada/baz.html"/&gt;,
120      * then the qualified name would be "{http://xyz.foo.com/yada/baz.html}foo".
121      * Note that no prefix is used.</p>
122      *
123      * @param name The name of the parameter, which may begin with a
124      * namespace URI in curly braces ({}).
125      * @param value The value object.  This can be any valid Java object. It is
126      * up to the processor to provide the proper object coersion or to simply
127      * pass the object on for use in an extension.
128      *
129      * @throws NullPointerException If value is null.
130      */
131      public abstract void setParameter(String name, Object value);
132 
133     /**
134      * Get a parameter that was explicitly set with setParameter.
135      *
136      * <p>This method does not return a default parameter value, which
137      * cannot be determined until the node context is evaluated during
138      * the transformation process.
139      *
140      * @param name of <code>Object</code> to get
141      *
142      * @return A parameter that has been set with setParameter.
143      */
144     public abstract Object getParameter(String name);
145 
146     /**
147      * <p>Set a list of parameters.</p>
148      *
149      * <p>Note that the list of parameters is specified as a
150      * <code>Properties</code> <code>Object</code> which limits the parameter
151      * values to <code>String</code>s.  Multiple calls to
152      * {@link #setParameter(String name, Object value)} should be used when the
153      * desired values are non-<code>String</code> <code>Object</code>s.
154      * The parameter names should conform as specified in
155      * {@link #setParameter(String name, Object value)}.
156      * An <code>IllegalArgumentException</code> is thrown if any names do not
157      * conform.</p>
158      *
159      * <p>New parameters in the list are added to any existing parameters.
160      * If the name of a new parameter is equal to the name of an existing
161      * parameter as determined by {@link java.lang.Object#equals(Object obj)},
162      *  the existing parameter is set to the new value.</p>
163      *
164      * @param params Parameters to set.
165      *
166      * @throws IllegalArgumentException If any parameter names do not conform
167      *   to the naming rules.
168      */
169 
170     /**
171      * Clear all parameters set with setParameter.
172      */
173     public abstract void clearParameters();
174 
175     /**
176      * Set an object that will be used to resolve URIs used in
177      * document().
178      *
179      * <p>If the resolver argument is null, the URIResolver value will
180      * be cleared and the transformer will no longer have a resolver.</p>
181      *
182      * @param resolver An object that implements the URIResolver interface,
183      * or null.
184      */
185     public abstract void setURIResolver(URIResolver resolver);
186 
187     /**
188      * Get an object that will be used to resolve URIs used in
189      * document().
190      *
191      * @return An object that implements the URIResolver interface,
192      * or null.
193      */
194     public abstract URIResolver getURIResolver();
195 
196     /**
197      * Set the output properties for the transformation.  These
198      * properties will override properties set in the Templates
199      * with xsl:output.
200      *
201      * <p>If argument to this function is null, any properties
202      * previously set are removed, and the value will revert to the value
203      * defined in the templates object.</p>
204      *
205      * <p>Pass a qualified property key name as a two-part string, the namespace
206      * URI enclosed in curly braces ({}), followed by the local name. If the
207      * name has a null URL, the String only contain the local name. An
208      * application can safely check for a non-null URI by testing to see if the
209      * first character of the name is a '{' character.</p>
210      * <p>For example, if a URI and local name were obtained from an element
211      * defined with &lt;xyz:foo
212      * xmlns:xyz="http://xyz.foo.com/yada/baz.html"/&gt;,
213      * then the qualified name would be "{http://xyz.foo.com/yada/baz.html}foo".
214      * Note that no prefix is used.</p>
215      * An <code>IllegalArgumentException</code> is thrown  if any of the
216      * argument keys are not recognized and are not namespace qualified.
217      *
218      * @param oformat A set of output properties that will be
219      *   used to override any of the same properties in affect
220      *   for the transformation.
221      *
222      * @throws IllegalArgumentException When keys are not recognized and
223      *   are not namespace qualified.
224      *
225      * @see javax.xml.transform.OutputKeys
226      * @see java.util.Properties
227      *
228      */
229     public abstract void setOutputProperties(Properties oformat);
230 
231     /**
232      * <p>Get a copy of the output properties for the transformation.</p>
233      *
234      * <p>The properties returned should contain properties set by the user,
235      * and properties set by the stylesheet, and these properties
236      * are "defaulted" by default properties specified by
237      * <a href="http://www.w3.org/TR/xslt#output">section 16 of the
238      * XSL Transformations (XSLT) W3C Recommendation</a>.  The properties that
239      * were specifically set by the user or the stylesheet should be in the base
240      * Properties list, while the XSLT default properties that were not
241      * specifically set should be the default Properties list.  Thus,
242      * getOutputProperties().getProperty(String key) will obtain any
243      * property in that was set by {@link #setOutputProperty},
244      * {@link #setOutputProperties}, in the stylesheet, <em>or</em> the default
245      * properties, while
246      * getOutputProperties().get(String key) will only retrieve properties
247      * that were explicitly set by {@link #setOutputProperty},
248      * {@link #setOutputProperties}, or in the stylesheet.</p>
249      *
250      * <p>Note that mutation of the Properties object returned will not
251      * effect the properties that the transformer contains.</p>
252      *
253      * <p>If any of the argument keys are not recognized and are not
254      * namespace qualified, the property will be ignored and not returned.
255      * In other words the behaviour is not orthogonal with
256      * {@link #setOutputProperties setOutputProperties}.</p>
257      *
258      * @return A copy of the set of output properties in effect for
259      *   the next transformation.
260      *
261      * @see javax.xml.transform.OutputKeys
262      * @see java.util.Properties
263      * @see <a href="http://www.w3.org/TR/xslt#output">
264      *   XSL Transformations (XSLT) Version 1.0</a>
265      */
266     public abstract Properties getOutputProperties();
267 
268     /**
269      * Set an output property that will be in effect for the
270      * transformation.
271      *
272      * <p>Pass a qualified property name as a two-part string, the namespace URI
273      * enclosed in curly braces ({}), followed by the local name. If the
274      * name has a null URL, the String only contain the local name. An
275      * application can safely check for a non-null URI by testing to see if the
276      * first character of the name is a '{' character.</p>
277      * <p>For example, if a URI and local name were obtained from an element
278      * defined with &lt;xyz:foo
279      * xmlns:xyz="http://xyz.foo.com/yada/baz.html"/&gt;,
280      * then the qualified name would be "{http://xyz.foo.com/yada/baz.html}foo".
281      * Note that no prefix is used.</p>
282      *
283      * <p>The Properties object that was passed to {@link #setOutputProperties}
284      * won't be effected by calling this method.</p>
285      *
286      * @param name A non-null String that specifies an output
287      * property name, which may be namespace qualified.
288      * @param value The non-null string value of the output property.
289      *
290      * @throws IllegalArgumentException If the property is not supported, and is
291      * not qualified with a namespace.
292      *
293      * @see javax.xml.transform.OutputKeys
294      */
295     public abstract void setOutputProperty(String name, String value)
296         throws IllegalArgumentException;
297 
298     /**
299      * <p>Get an output property that is in effect for the transformer.</p>
300      *
301      * <p>If a property has been set using {@link #setOutputProperty},
302      * that value will be returned. Otherwise, if a property is explicitly
303      * specified in the stylesheet, that value will be returned. If
304      * the value of the property has been defaulted, that is, if no
305      * value has been set explicitly either with {@link #setOutputProperty} or
306      * in the stylesheet, the result may vary depending on
307      * implementation and input stylesheet.</p>
308      *
309      * @param name A non-null String that specifies an output
310      * property name, which may be namespace qualified.
311      *
312      * @return The string value of the output property, or null
313      * if no property was found.
314      *
315      * @throws IllegalArgumentException If the property is not supported.
316      *
317      * @see javax.xml.transform.OutputKeys
318      */
319     public abstract String getOutputProperty(String name)
320         throws IllegalArgumentException;
321 
322     /**
323      * Set the error event listener in effect for the transformation.
324      *
325      * @param listener The new error listener.
326      *
327      * @throws IllegalArgumentException if listener is null.
328      */
329     public abstract void setErrorListener(ErrorListener listener)
330         throws IllegalArgumentException;
331 
332     /**
333      * Get the error event handler in effect for the transformation.
334      * Implementations must provide a default error listener.
335      *
336      * @return The current error handler, which should never be null.
337      */
338     public abstract ErrorListener getErrorListener();
339 }