1 /*
   2  * Copyright (c) 2000, 2006, 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  *
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  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 /**
  29  * <p>A TransformerFactory instance can be used to create
  30  * {@link javax.xml.transform.Transformer} and
  31  * {@link javax.xml.transform.Templates} objects.</p>
  32  *
  33  * <p>The system property that determines which Factory implementation
  34  * to create is named <code>"javax.xml.transform.TransformerFactory"</code>.
  35  * This property names a concrete subclass of the
  36  * <code>TransformerFactory</code> abstract class. If the property is not
  37  * defined, a platform default is be used.</p>
  38  *
  39  * @author <a href="mailto:Jeff.Suttor@Sun.com">Jeff Suttor</a>
  40  * @author <a href="mailto:Neeraj.Bajaj@sun.com">Neeraj Bajaj</a>
  41  *
  42  * @since 1.5
  43  */
  44 public abstract class TransformerFactory {
  45 
  46     /**
  47      * Default constructor is protected on purpose.
  48      */
  49     protected TransformerFactory() { }
  50 
  51 
  52 
  53     /**
  54      * <p>Obtain a new instance of a <code>TransformerFactory</code>.
  55      * This static method creates a new factory instance
  56      * This method uses the following ordered lookup procedure to determine
  57      * the <code>TransformerFactory</code> implementation class to
  58      * load:</p>
  59      * <ul>
  60      * <li>
  61      * Use the <code>javax.xml.transform.TransformerFactory</code> system
  62      * property.
  63      * </li>
  64      * <li>
  65      * Use the properties file "lib/jaxp.properties" in the JRE directory.
  66      * This configuration file is in standard <code>java.util.Properties
  67      * </code> format and contains the fully qualified name of the
  68      * implementation class with the key being the system property defined
  69      * above.
  70      *
  71      * The jaxp.properties file is read only once by the JAXP implementation
  72      * and it's values are then cached for future use.  If the file does not exist
  73      * when the first attempt is made to read from it, no further attempts are
  74      * made to check for its existence.  It is not possible to change the value
  75      * of any property in jaxp.properties after it has been read for the first time.
  76      * </li>
  77      * <li>
  78      * Use the Services API (as detailed in the JAR specification), if
  79      * available, to determine the classname. The Services API will look
  80      * for a classname in the file
  81      * <code>META-INF/services/javax.xml.transform.TransformerFactory</code>
  82      * in jars available to the runtime.
  83      * </li>
  84      * <li>
  85      * Platform default <code>TransformerFactory</code> instance.
  86      * </li>
  87      * </ul>
  88      *
  89      * <p>Once an application has obtained a reference to a <code>
  90      * TransformerFactory</code> it can use the factory to configure
  91      * and obtain transformer instances.</p>
  92      *
  93      * @return new TransformerFactory instance, never null.
  94      *
  95      * @throws TransformerFactoryConfigurationError Thrown if the implementation
  96      *    is not available or cannot be instantiated.
  97      */
  98     public static TransformerFactory newInstance()
  99         throws TransformerFactoryConfigurationError {
 100         try {
 101             return (TransformerFactory) FactoryFinder.find(
 102             /* The default property name according to the JAXP spec */
 103             "javax.xml.transform.TransformerFactory",
 104             /* The fallback implementation class name, XSLTC */
 105             "com.sun.org.apache.xalan.internal.xsltc.trax.TransformerFactoryImpl");
 106         } catch (FactoryFinder.ConfigurationError e) {
 107             throw new TransformerFactoryConfigurationError(
 108                 e.getException(),
 109                 e.getMessage());
 110         }
 111     }
 112 
 113     /**
 114      * <p>Obtain a new instance of a <code>TransformerFactory</code> from factory class name.
 115      * This function is useful when there are multiple providers in the classpath.
 116      * It gives more control to the application as it can specify which provider
 117      * should be loaded.</p>
 118      *
 119      * <p>Once an application has obtained a reference to a <code>
 120      * TransformerFactory</code> it can use the factory to configure
 121      * and obtain transformer instances.</p>
 122      *
 123      * <h2>Tip for Trouble-shooting</h2>
 124      * <p>Setting the <code>jaxp.debug</code> system property will cause
 125      * this method to print a lot of debug messages
 126      * to <code>System.err</code> about what it is doing and where it is looking at.</p>
 127      *
 128      * <p> If you have problems try:</p>
 129      * <pre>
 130      * java -Djaxp.debug=1 YourProgram ....
 131      * </pre>
 132      *
 133      * @param factoryClassName fully qualified factory class name that provides implementation of <code>javax.xml.transform.TransformerFactory</code>.
 134      *
 135      * @param classLoader <code>ClassLoader</code> used to load the factory class. If <code>null</code>
 136      *                     current <code>Thread</code>'s context classLoader is used to load the factory class.
 137      *
 138      * @return new TransformerFactory instance, never null.
 139      *
 140      * @throws TransformerFactoryConfigurationError
 141      *                    if <code>factoryClassName</code> is <code>null</code>, or
 142      *                   the factory class cannot be loaded, instantiated.
 143      *
 144      * @see #newInstance()
 145      *
 146      * @since 1.6
 147      */
 148     public static TransformerFactory newInstance(String factoryClassName, ClassLoader classLoader)
 149         throws TransformerFactoryConfigurationError{
 150         try {
 151             //do not fallback if given classloader can't find the class, throw exception
 152             return (TransformerFactory) FactoryFinder.newInstance(factoryClassName, classLoader, false);
 153         } catch (FactoryFinder.ConfigurationError e) {
 154             throw new TransformerFactoryConfigurationError(
 155                 e.getException(),
 156                 e.getMessage());
 157         }
 158     }
 159     /**
 160      * <p>Process the <code>Source</code> into a <code>Transformer</code>
 161      * <code>Object</code>.  The <code>Source</code> is an XSLT document that
 162      * conforms to <a href="http://www.w3.org/TR/xslt">
 163      * XSL Transformations (XSLT) Version 1.0</a>.  Care must
 164      * be taken not to use this <code>Transformer</code> in multiple
 165      * <code>Thread</code>s running concurrently.
 166      * Different <code>TransformerFactories</code> can be used concurrently by
 167      * different <code>Thread</code>s.</p>
 168      *
 169      * @param source <code>Source </code> of XSLT document used to create
 170      *   <code>Transformer</code>.
 171      *   Examples of XML <code>Source</code>s include
 172      *   {@link javax.xml.transform.dom.DOMSource DOMSource},
 173      *   {@link javax.xml.transform.sax.SAXSource SAXSource}, and
 174      *   {@link javax.xml.transform.stream.StreamSource StreamSource}.
 175      *
 176      * @return A <code>Transformer</code> object that may be used to perform
 177      *   a transformation in a single <code>Thread</code>, never
 178      *   <code>null</code>.
 179      *
 180      * @throws TransformerConfigurationException Thrown if there are errors when
 181      *    parsing the <code>Source</code> or it is not possible to create a
 182      *   <code>Transformer</code> instance.
 183      *
 184      * @see <a href="http://www.w3.org/TR/xslt">
 185      *   XSL Transformations (XSLT) Version 1.0</a>
 186      */
 187     public abstract Transformer newTransformer(Source source)
 188         throws TransformerConfigurationException;
 189 
 190     /**
 191      * <p>Create a new <code>Transformer</code> that performs a copy
 192      * of the <code>Source</code> to the <code>Result</code>.
 193      * i.e. the "<em>identity transform</em>".</p>
 194      *
 195      * @return A Transformer object that may be used to perform a transformation
 196      * in a single thread, never null.
 197      *
 198      * @throws TransformerConfigurationException When it is not
 199      *   possible to create a <code>Transformer</code> instance.
 200      */
 201     public abstract Transformer newTransformer()
 202         throws TransformerConfigurationException;
 203 
 204     /**
 205      * Process the Source into a Templates object, which is a
 206      * a compiled representation of the source. This Templates object
 207      * may then be used concurrently across multiple threads.  Creating
 208      * a Templates object allows the TransformerFactory to do detailed
 209      * performance optimization of transformation instructions, without
 210      * penalizing runtime transformation.
 211      *
 212      * @param source An object that holds a URL, input stream, etc.
 213      *
 214      * @return A Templates object capable of being used for transformation
 215      *   purposes, never <code>null</code>.
 216      *
 217      * @throws TransformerConfigurationException When parsing to
 218      *   construct the Templates object fails.
 219      */
 220     public abstract Templates newTemplates(Source source)
 221         throws TransformerConfigurationException;
 222 
 223     /**
 224      * <p>Get the stylesheet specification(s) associated with the
 225      * XML <code>Source</code> document via the
 226      * <a href="http://www.w3.org/TR/xml-stylesheet/">
 227      * xml-stylesheet processing instruction</a> that match the given criteria.
 228      * Note that it is possible to return several stylesheets, in which case
 229      * they are applied as if they were a list of imports or cascades in a
 230      * single stylesheet.</p>
 231      *
 232      * @param source The XML source document.
 233      * @param media The media attribute to be matched.  May be null, in which
 234      *      case the prefered templates will be used (i.e. alternate = no).
 235      * @param title The value of the title attribute to match.  May be null.
 236      * @param charset The value of the charset attribute to match.  May be null.
 237      *
 238      * @return A <code>Source</code> <code>Object</code> suitable for passing
 239      *   to the <code>TransformerFactory</code>.
 240      *
 241      * @throws TransformerConfigurationException An <code>Exception</code>
 242      *   is thrown if an error occurings during parsing of the
 243      *   <code>source</code>.
 244      *
 245      * @see <a href="http://www.w3.org/TR/xml-stylesheet/">
 246      *   Associating Style Sheets with XML documents Version 1.0</a>
 247      */
 248     public abstract Source getAssociatedStylesheet(
 249         Source source,
 250         String media,
 251         String title,
 252         String charset)
 253         throws TransformerConfigurationException;
 254 
 255     /**
 256      * Set an object that is used by default during the transformation
 257      * to resolve URIs used in document(), xsl:import, or xsl:include.
 258      *
 259      * @param resolver An object that implements the URIResolver interface,
 260      * or null.
 261      */
 262     public abstract void setURIResolver(URIResolver resolver);
 263 
 264     /**
 265      * Get the object that is used by default during the transformation
 266      * to resolve URIs used in document(), xsl:import, or xsl:include.
 267      *
 268      * @return The URIResolver that was set with setURIResolver.
 269      */
 270     public abstract URIResolver getURIResolver();
 271 
 272     //======= CONFIGURATION METHODS =======
 273 
 274         /**
 275          * <p>Set a feature for this <code>TransformerFactory</code> and <code>Transformer</code>s
 276          * or <code>Template</code>s created by this factory.</p>
 277          *
 278          * <p>
 279          * Feature names are fully qualified {@link java.net.URI}s.
 280          * Implementations may define their own features.
 281          * An {@link TransformerConfigurationException} is thrown if this <code>TransformerFactory</code> or the
 282          * <code>Transformer</code>s or <code>Template</code>s it creates cannot support the feature.
 283          * It is possible for an <code>TransformerFactory</code> to expose a feature value but be unable to change its state.
 284          * </p>
 285          *
 286          * <p>All implementations are required to support the {@link javax.xml.XMLConstants#FEATURE_SECURE_PROCESSING} feature.
 287          * When the feature is:</p>
 288          * <ul>
 289          *   <li>
 290          *     <code>true</code>: the implementation will limit XML processing to conform to implementation limits
 291          *     and behave in a secure fashion as defined by the implementation.
 292          *     Examples include resolving user defined style sheets and functions.
 293          *     If XML processing is limited for security reasons, it will be reported via a call to the registered
 294          *     {@link ErrorListener#fatalError(TransformerException exception)}.
 295          *     See {@link  #setErrorListener(ErrorListener listener)}.
 296          *   </li>
 297          *   <li>
 298          *     <code>false</code>: the implementation will processing XML according to the XML specifications without
 299          *     regard to possible implementation limits.
 300          *   </li>
 301          * </ul>
 302          *
 303          * @param name Feature name.
 304          * @param value Is feature state <code>true</code> or <code>false</code>.
 305          *
 306          * @throws TransformerConfigurationException if this <code>TransformerFactory</code>
 307          *   or the <code>Transformer</code>s or <code>Template</code>s it creates cannot support this feature.
 308      * @throws NullPointerException If the <code>name</code> parameter is null.
 309          */
 310         public abstract void setFeature(String name, boolean value)
 311                 throws TransformerConfigurationException;
 312 
 313     /**
 314      * Look up the value of a feature.
 315      *
 316          * <p>
 317          * Feature names are fully qualified {@link java.net.URI}s.
 318          * Implementations may define their own features.
 319          * <code>false</code> is returned if this <code>TransformerFactory</code> or the
 320          * <code>Transformer</code>s or <code>Template</code>s it creates cannot support the feature.
 321          * It is possible for an <code>TransformerFactory</code> to expose a feature value but be unable to change its state.
 322          * </p>
 323          *
 324          * @param name Feature name.
 325          *
 326      * @return The current state of the feature, <code>true</code> or <code>false</code>.
 327      *
 328      * @throws NullPointerException If the <code>name</code> parameter is null.
 329      */
 330     public abstract boolean getFeature(String name);
 331 
 332     /**
 333      * Allows the user to set specific attributes on the underlying
 334      * implementation.  An attribute in this context is defined to
 335      * be an option that the implementation provides.
 336      * An <code>IllegalArgumentException</code> is thrown if the underlying
 337      * implementation doesn't recognize the attribute.
 338      *
 339      * @param name The name of the attribute.
 340      * @param value The value of the attribute.
 341      *
 342      * @throws IllegalArgumentException When implementation does not
 343      *   recognize the attribute.
 344      */
 345     public abstract void setAttribute(String name, Object value);
 346 
 347     /**
 348      * Allows the user to retrieve specific attributes on the underlying
 349      * implementation.
 350      * An <code>IllegalArgumentException</code> is thrown if the underlying
 351      * implementation doesn't recognize the attribute.
 352      *
 353      * @param name The name of the attribute.
 354      *
 355      * @return value The value of the attribute.
 356      *
 357      * @throws IllegalArgumentException When implementation does not
 358      *   recognize the attribute.
 359      */
 360     public abstract Object getAttribute(String name);
 361 
 362     /**
 363      * Set the error event listener for the TransformerFactory, which
 364      * is used for the processing of transformation instructions,
 365      * and not for the transformation itself.
 366      * An <code>IllegalArgumentException</code> is thrown if the
 367      * <code>ErrorListener</code> listener is <code>null</code>.
 368      *
 369      * @param listener The new error listener.
 370      *
 371      * @throws IllegalArgumentException When <code>listener</code> is
 372      *   <code>null</code>
 373      */
 374     public abstract void setErrorListener(ErrorListener listener);
 375 
 376     /**
 377      * Get the error event handler for the TransformerFactory.
 378      *
 379      * @return The current error handler, which should never be null.
 380      */
 381     public abstract ErrorListener getErrorListener();
 382 
 383 }