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  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).
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  25 
  26 package javax.xml.transform;
  27 
  28 import com.sun.org.apache.xalan.internal.xsltc.trax.TransformerFactoryImpl;
  29 
  30 /**
  31  * <p>A TransformerFactory instance can be used to create
  32  * {@link javax.xml.transform.Transformer} and
  33  * {@link javax.xml.transform.Templates} objects.
  34  *
  35  * <p>The system property that determines which Factory implementation
  36  * to create is named {@code "javax.xml.transform.TransformerFactory"}.
  37  * This property names a concrete subclass of the
  38  * {@code TransformerFactory} abstract class. If the property is not
  39  * defined, a platform default is be used.
  40  *
  41  * @author Jeff Suttor
  42  * @author Neeraj Bajaj
  43  *
  44  * @since 1.5
  45  */
  46 public abstract class TransformerFactory {
  47 
  48     /**
  49      * Default constructor is protected on purpose.
  50      */
  51     protected TransformerFactory() { }
  52 
  53 
  54 
  55     /**
  56      * Creates a new instance of the {@code TransformerFactory} builtin
  57      * system-default implementation.
  58      *
  59      * @return A new instance of the {@code TransformerFactory} builtin
  60      *         system-default implementation.
  61      *
  62      * @since 9
  63      */
  64     public static TransformerFactory newDefaultInstance() {
  65         return new TransformerFactoryImpl();
  66     }
  67 
  68     /**
  69      * Obtain a new instance of a {@code TransformerFactory}.
  70      * This static method creates a new factory instance.
  71      * <p>
  72      * This method uses the following ordered lookup procedure to determine
  73      * the {@code TransformerFactory} implementation class to load:
  74      * <ul>
  75      * <li>
  76      * Use the {@code javax.xml.transform.TransformerFactory} system
  77      * property.
  78      * </li>
  79      * <li>
  80      * <p>
  81      * Use the configuration file "jaxp.properties". The file is in standard
  82      * {@link java.util.Properties} format and typically located in the
  83      * {@code conf} directory of the Java installation. It contains the fully qualified
  84      * name of the implementation class with the key being the system property
  85      * defined above.
  86      * <p>
  87      * The jaxp.properties file is read only once by the JAXP implementation
  88      * and its values are then cached for future use.  If the file does not exist
  89      * when the first attempt is made to read from it, no further attempts are
  90      * made to check for its existence.  It is not possible to change the value
  91      * of any property in jaxp.properties after it has been read for the first time.
  92      * </li>
  93      * <li>
  94      * <p>
  95      * Use the service-provider loading facility, defined by the
  96      *   {@link java.util.ServiceLoader} class, to attempt to locate and load an
  97      *   implementation of the service using the {@linkplain
  98      *   java.util.ServiceLoader#load(java.lang.Class) default loading mechanism}:
  99      *   the service-provider loading facility will use the {@linkplain
 100      *   java.lang.Thread#getContextClassLoader() current thread's context class loader}
 101      *   to attempt to load the service. If the context class
 102      *   loader is null, the {@linkplain
 103      *   ClassLoader#getSystemClassLoader() system class loader} will be used.
 104      * </li>
 105      * <li>
 106      * <p>
 107      *   Otherwise, the {@linkplain #newDefaultInstance() system-default}
 108      *   implementation is returned.
 109      * </li>
 110      * </ul>
 111      *
 112      * <p>
 113      * Once an application has obtained a reference to a
 114      * {@code TransformerFactory} it can use the factory to configure
 115      * and obtain transformer instances.
 116      *
 117      * @return new TransformerFactory instance, never null.
 118      *
 119      * @throws TransformerFactoryConfigurationError Thrown in case of {@linkplain
 120      * java.util.ServiceConfigurationError service configuration error} or if
 121      * the implementation is not available or cannot be instantiated.
 122      */
 123     public static TransformerFactory newInstance()
 124         throws TransformerFactoryConfigurationError {
 125 
 126         return FactoryFinder.find(
 127             /* The default property name according to the JAXP spec */
 128             TransformerFactory.class,
 129             /* The fallback implementation class name, XSLTC */
 130             "com.sun.org.apache.xalan.internal.xsltc.trax.TransformerFactoryImpl");
 131     }
 132 
 133     /**
 134      * Obtain a new instance of a {@code TransformerFactory} from factory class name.
 135      * This function is useful when there are multiple providers in the classpath.
 136      * It gives more control to the application as it can specify which provider
 137      * should be loaded.
 138      *
 139      * <p>Once an application has obtained a reference to a
 140      * {@code TransformerFactory} it can use the factory to configure
 141      * and obtain transformer instances.
 142      *
 143      * <h2>Tip for Trouble-shooting</h2>
 144      * <p>Setting the {@code jaxp.debug} system property will cause
 145      * this method to print a lot of debug messages
 146      * to {@code System.err} about what it is doing and where it is looking at.
 147      *
 148      * <p> If you have problems try:
 149      * <pre>
 150      * java -Djaxp.debug=1 YourProgram ....
 151      * </pre>
 152      *
 153      * @param factoryClassName fully qualified factory class name that provides implementation of {@code javax.xml.transform.TransformerFactory}.
 154      *
 155      * @param classLoader {@code ClassLoader} used to load the factory class. If {@code null}
 156      *                     current {@code Thread}'s context classLoader is used to load the factory class.
 157      *
 158      * @return new TransformerFactory instance, never null.
 159      *
 160      * @throws TransformerFactoryConfigurationError
 161      *                    if {@code factoryClassName} is {@code null}, or
 162      *                   the factory class cannot be loaded, instantiated.
 163      *
 164      * @see #newInstance()
 165      *
 166      * @since 1.6
 167      */
 168     public static TransformerFactory newInstance(String factoryClassName, ClassLoader classLoader)
 169         throws TransformerFactoryConfigurationError{
 170 
 171         //do not fallback if given classloader can't find the class, throw exception
 172         return  FactoryFinder.newInstance(TransformerFactory.class,
 173                     factoryClassName, classLoader, false);
 174     }
 175     /**
 176      * Process the {@code Source} into a {@code Transformer}
 177      * {@code Object}.  The {@code Source} is an XSLT document that
 178      * conforms to <a href="http://www.w3.org/TR/xslt">
 179      * XSL Transformations (XSLT) Version 1.0</a>.  Care must
 180      * be taken not to use this {@code Transformer} in multiple
 181      * {@code Thread}s running concurrently.
 182      * Different {@code TransformerFactories} can be used concurrently by
 183      * different {@code Thread}s.
 184      *
 185      * @param source {@code Source } of XSLT document used to create
 186      *   {@code Transformer}.
 187      *   Examples of XML {@code Source}s include
 188      *   {@link javax.xml.transform.dom.DOMSource DOMSource},
 189      *   {@link javax.xml.transform.sax.SAXSource SAXSource}, and
 190      *   {@link javax.xml.transform.stream.StreamSource StreamSource}.
 191      *
 192      * @return A {@code Transformer} object that may be used to perform
 193      *   a transformation in a single {@code Thread}, never
 194      *   {@code null}.
 195      *
 196      * @throws TransformerConfigurationException Thrown if there are errors when
 197      *    parsing the {@code Source} or it is not possible to create a
 198      *   {@code Transformer} instance.
 199      *
 200      * @see <a href="http://www.w3.org/TR/xslt">
 201      *   XSL Transformations (XSLT) Version 1.0</a>
 202      */
 203     public abstract Transformer newTransformer(Source source)
 204         throws TransformerConfigurationException;
 205 
 206     /**
 207      * Create a new {@code Transformer} that performs a copy
 208      * of the {@code Source} to the {@code Result}.
 209      * i.e. the "<em>identity transform</em>".
 210      *
 211      * @return A Transformer object that may be used to perform a transformation
 212      * in a single thread, never null.
 213      *
 214      * @throws TransformerConfigurationException When it is not
 215      *   possible to create a {@code Transformer} instance.
 216      */
 217     public abstract Transformer newTransformer()
 218         throws TransformerConfigurationException;
 219 
 220     /**
 221      * Process the Source into a Templates object, which is a
 222      * a compiled representation of the source. This Templates object
 223      * may then be used concurrently across multiple threads.  Creating
 224      * a Templates object allows the TransformerFactory to do detailed
 225      * performance optimization of transformation instructions, without
 226      * penalizing runtime transformation.
 227      *
 228      * @param source An object that holds a URL, input stream, etc.
 229      *
 230      * @return A Templates object capable of being used for transformation
 231      *   purposes, never {@code null}.
 232      *
 233      * @throws TransformerConfigurationException When parsing to
 234      *   construct the Templates object fails.
 235      */
 236     public abstract Templates newTemplates(Source source)
 237         throws TransformerConfigurationException;
 238 
 239     /**
 240      * Get the stylesheet specification(s) associated with the
 241      * XML {@code Source} document via the
 242      * <a href="http://www.w3.org/TR/xml-stylesheet/">
 243      * xml-stylesheet processing instruction</a> that match the given criteria.
 244      * Note that it is possible to return several stylesheets, in which case
 245      * they are applied as if they were a list of imports or cascades in a
 246      * single stylesheet.
 247      *
 248      * @param source The XML source document.
 249      * @param media The media attribute to be matched.  May be null, in which
 250      *      case the prefered templates will be used (i.e. alternate = no).
 251      * @param title The value of the title attribute to match.  May be null.
 252      * @param charset The value of the charset attribute to match.  May be null.
 253      *
 254      * @return A {@code Source} {@code Object} suitable for passing
 255      *   to the {@code TransformerFactory}.
 256      *
 257      * @throws TransformerConfigurationException An {@code Exception}
 258      *   is thrown if an error occurings during parsing of the
 259      *   {@code source}.
 260      *
 261      * @see <a href="http://www.w3.org/TR/xml-stylesheet/">
 262      *   Associating Style Sheets with XML documents Version 1.0</a>
 263      */
 264     public abstract Source getAssociatedStylesheet(
 265         Source source,
 266         String media,
 267         String title,
 268         String charset)
 269         throws TransformerConfigurationException;
 270 
 271     /**
 272      * Set an object that is used by default during the transformation
 273      * to resolve URIs used in document(), xsl:import, or xsl:include.
 274      *
 275      * @param resolver An object that implements the URIResolver interface,
 276      * or null.
 277      */
 278     public abstract void setURIResolver(URIResolver resolver);
 279 
 280     /**
 281      * Get the object that is used by default during the transformation
 282      * to resolve URIs used in document(), xsl:import, or xsl:include.
 283      *
 284      * @return The URIResolver that was set with setURIResolver.
 285      */
 286     public abstract URIResolver getURIResolver();
 287 
 288     //======= CONFIGURATION METHODS =======
 289 
 290         /**
 291          * <p>Set a feature for this {@code TransformerFactory} and {@code Transformer}s
 292          * or {@code Template}s created by this factory.
 293          *
 294          * <p>
 295          * Feature names are fully qualified {@link java.net.URI}s.
 296          * Implementations may define their own features.
 297          * An {@link TransformerConfigurationException} is thrown if this {@code TransformerFactory} or the
 298          * {@code Transformer}s or {@code Template}s it creates cannot support the feature.
 299          * It is possible for an {@code TransformerFactory} to expose a feature value but be unable to change its state.
 300          *
 301          * <p>All implementations are required to support the {@link javax.xml.XMLConstants#FEATURE_SECURE_PROCESSING} feature.
 302          * When the feature is:
 303          * <ul>
 304          *   <li>
 305          *     {@code true}: the implementation will limit XML processing to conform to implementation limits
 306          *     and behave in a secure fashion as defined by the implementation.
 307          *     Examples include resolving user defined style sheets and functions.
 308          *     If XML processing is limited for security reasons, it will be reported via a call to the registered
 309          *     {@link ErrorListener#fatalError(TransformerException exception)}.
 310          *     See {@link  #setErrorListener(ErrorListener listener)}.
 311          *   </li>
 312          *   <li>
 313          *     {@code false}: the implementation will processing XML according to the XML specifications without
 314          *     regard to possible implementation limits.
 315          *   </li>
 316          * </ul>
 317          *
 318          * @param name Feature name.
 319          * @param value Is feature state {@code true} or {@code false}.
 320          *
 321          * @throws TransformerConfigurationException if this {@code TransformerFactory}
 322          *   or the {@code Transformer}s or {@code Template}s it creates cannot support this feature.
 323      * @throws NullPointerException If the {@code name} parameter is null.
 324          */
 325         public abstract void setFeature(String name, boolean value)
 326                 throws TransformerConfigurationException;
 327 
 328     /**
 329      * Look up the value of a feature.
 330      *
 331          * <p>
 332          * Feature names are fully qualified {@link java.net.URI}s.
 333          * Implementations may define their own features.
 334          * {@code false} is returned if this {@code TransformerFactory} or the
 335          * {@code Transformer}s or {@code Template}s it creates cannot support the feature.
 336          * It is possible for an {@code TransformerFactory} to expose a feature value but be unable to change its state.
 337          *
 338          * @param name Feature name.
 339          *
 340      * @return The current state of the feature, {@code true} or {@code false}.
 341      *
 342      * @throws NullPointerException If the {@code name} parameter is null.
 343      */
 344     public abstract boolean getFeature(String name);
 345 
 346     /**
 347      * Allows the user to set specific attributes on the underlying
 348      * implementation.  An attribute in this context is defined to
 349      * be an option that the implementation provides.
 350      * An {@code IllegalArgumentException} is thrown if the underlying
 351      * implementation doesn't recognize the attribute.
 352      * <p>
 353      * All implementations that implement JAXP 1.5 or newer are required to
 354      * support the {@link javax.xml.XMLConstants#ACCESS_EXTERNAL_DTD}  and
 355      * {@link javax.xml.XMLConstants#ACCESS_EXTERNAL_STYLESHEET} properties.
 356      *
 357      * <ul>
 358      *   <li>
 359      *      <p>
 360      *      Access to external DTDs in the source file is restricted to the protocols
 361      *      specified by the {@link javax.xml.XMLConstants#ACCESS_EXTERNAL_DTD} property.
 362      *      If access is denied during transformation due to the restriction of this property,
 363      *      {@link javax.xml.transform.TransformerException} will be thrown by
 364      *      {@link javax.xml.transform.Transformer#transform(Source, Result)}.
 365      *
 366      *      <p>
 367      *      Access to external DTDs in the stylesheet is restricted to the protocols
 368      *      specified by the {@link javax.xml.XMLConstants#ACCESS_EXTERNAL_DTD} property.
 369      *      If access is denied during the creation of a new transformer due to the
 370      *      restriction of this property,
 371      *      {@link javax.xml.transform.TransformerConfigurationException} will be thrown
 372      *      by the {@link #newTransformer(Source)} method.
 373      *
 374      *      <p>
 375      *      Access to external reference set by the stylesheet processing instruction,
 376      *      Import and Include element is restricted to the protocols specified by the
 377      *      {@link javax.xml.XMLConstants#ACCESS_EXTERNAL_STYLESHEET} property.
 378      *      If access is denied during the creation of a new transformer due to the
 379      *      restriction of this property,
 380      *      {@link javax.xml.transform.TransformerConfigurationException} will be thrown
 381      *      by the {@link #newTransformer(Source)} method.
 382      *
 383      *      <p>
 384      *      Access to external document through XSLT document function is restricted
 385      *      to the protocols specified by the property. If access is denied during
 386      *      the transformation due to the restriction of this property,
 387      *      {@link javax.xml.transform.TransformerException} will be thrown by the
 388      *      {@link javax.xml.transform.Transformer#transform(Source, Result)} method.
 389      *
 390      *   </li>
 391      * </ul>
 392      *
 393      * @param name The name of the attribute.
 394      * @param value The value of the attribute.
 395      *
 396      * @throws IllegalArgumentException When implementation does not
 397      *   recognize the attribute.
 398      */
 399     public abstract void setAttribute(String name, Object value);
 400 
 401     /**
 402      * Allows the user to retrieve specific attributes on the underlying
 403      * implementation.
 404      * An {@code IllegalArgumentException} is thrown if the underlying
 405      * implementation doesn't recognize the attribute.
 406      *
 407      * @param name The name of the attribute.
 408      *
 409      * @return value The value of the attribute.
 410      *
 411      * @throws IllegalArgumentException When implementation does not
 412      *   recognize the attribute.
 413      */
 414     public abstract Object getAttribute(String name);
 415 
 416     /**
 417      * Set the error event listener for the TransformerFactory, which
 418      * is used for the processing of transformation instructions,
 419      * and not for the transformation itself.
 420      * An {@code IllegalArgumentException} is thrown if the
 421      * {@code ErrorListener} listener is {@code null}.
 422      *
 423      * @param listener The new error listener.
 424      *
 425      * @throws IllegalArgumentException When {@code listener} is
 426      *   {@code null}
 427      */
 428     public abstract void setErrorListener(ErrorListener listener);
 429 
 430     /**
 431      * Get the error event handler for the TransformerFactory.
 432      *
 433      * @return The current error handler, which should never be null.
 434      */
 435     public abstract ErrorListener getErrorListener();
 436 
 437 }