XPathFactory.java revision 1038:ccad0993fc67
1114402Sru/* 2114402Sru * Copyright (c) 2003, 2016, Oracle and/or its affiliates. All rights reserved. 3114402Sru * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. 4114402Sru * 5114402Sru * This code is free software; you can redistribute it and/or modify it 6114402Sru * under the terms of the GNU General Public License version 2 only, as 7114402Sru * published by the Free Software Foundation. Oracle designates this 8114402Sru * particular file as subject to the "Classpath" exception as provided 9114402Sru * by Oracle in the LICENSE file that accompanied this code. 10114402Sru * 11114402Sru * This code is distributed in the hope that it will be useful, but WITHOUT 12114402Sru * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or 13114402Sru * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License 14114402Sru * version 2 for more details (a copy is included in the LICENSE file that 15114402Sru * accompanied this code). 16114402Sru * 17114402Sru * You should have received a copy of the GNU General Public License version 18114402Sru * 2 along with this work; if not, write to the Free Software Foundation, 19114402Sru * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. 20151497Sru * 21114402Sru * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA 22114402Sru * or visit www.oracle.com if you need additional information or have any 23114402Sru * questions. 24114402Sru */ 25114402Sru 26114402Srupackage javax.xml.xpath; 27114402Sru 28114402Sruimport com.sun.org.apache.xpath.internal.jaxp.XPathFactoryImpl; 29114402Sru 30114402Sru/** 31114402Sru * <p>An {@code XPathFactory} instance can be used to create 32114402Sru * {@link javax.xml.xpath.XPath} objects.</p> 33114402Sru * 34114402Sru *<p>See {@link #newInstance(String uri)} for lookup mechanism.</p> 35114402Sru * 36114402Sru * <p>The {@link XPathFactory} class is not thread-safe. In other words, 37114402Sru * it is the application's responsibility to ensure that at most 38114402Sru * one thread is using a {@link XPathFactory} object at any 39114402Sru * given moment. Implementations are encouraged to mark methods 40114402Sru * as <code>synchronized</code> to protect themselves from broken clients. 41114402Sru * 42114402Sru * <p>{@link XPathFactory} is not re-entrant. While one of the 43114402Sru * <code>newInstance</code> methods is being invoked, applications 44114402Sru * may not attempt to recursively invoke a <code>newInstance</code> method, 45114402Sru * even from the same thread. 46114402Sru * 47114402Sru * @author <a href="mailto:Norman.Walsh@Sun.com">Norman Walsh</a> 48114402Sru * @author <a href="mailto:Jeff.Suttor@Sun.com">Jeff Suttor</a> 49114402Sru * 50114402Sru * @since 1.5 51114402Sru */ 52114402Srupublic abstract class XPathFactory { 53114402Sru 54114402Sru 55114402Sru /** 56114402Sru * <p>The default property name according to the JAXP spec.</p> 57114402Sru */ 58114402Sru public static final String DEFAULT_PROPERTY_NAME = "javax.xml.xpath.XPathFactory"; 59114402Sru 60114402Sru /** 61114402Sru * <p>Default Object Model URI.</p> 62114402Sru */ 63114402Sru public static final String DEFAULT_OBJECT_MODEL_URI = "http://java.sun.com/jaxp/xpath/dom"; 64114402Sru 65114402Sru /** 66114402Sru *<p> Take care of restrictions imposed by java security model </p> 67114402Sru */ 68114402Sru private static SecuritySupport ss = new SecuritySupport() ; 69114402Sru 70114402Sru /** 71114402Sru * <p>Protected constructor as {@link #newInstance()} or {@link #newInstance(String uri)} 72114402Sru * or {@link #newInstance(String uri, String factoryClassName, ClassLoader classLoader)} 73114402Sru * should be used to create a new instance of an {@code XPathFactory}.</p> 74114402Sru */ 75114402Sru protected XPathFactory() { 76114402Sru } 77114402Sru 78114402Sru /** 79114402Sru * Creates a new instance of the {@code XPathFactory} builtin 80114402Sru * system-default implementation. 81114402Sru * 82114402Sru * @implSpec The {@code XPathFactory} builtin 83114402Sru * system-default implementation is only required to support the 84114402Sru * {@link #DEFAULT_OBJECT_MODEL_URI default object model}, the 85114402Sru * {@linkplain org.w3c.dom W3C DOM}, but may support additional 86114402Sru * object models. 87114402Sru * 88114402Sru * @return A new instance of the {@code XPathFactory} builtin 89114402Sru * system-default implementation. 90114402Sru * 91114402Sru * @since 9 92114402Sru */ 93114402Sru public static XPathFactory newDefaultInstance() { 94114402Sru return XPathFactoryImpl.newXPathFactoryNoServiceLoader(); 95114402Sru } 96114402Sru 97114402Sru /** 98114402Sru * <p>Get a new {@code XPathFactory} instance using the default object model, 99114402Sru * {@link #DEFAULT_OBJECT_MODEL_URI}, 100114402Sru * the W3C DOM.</p> 101114402Sru * 102114402Sru * <p>This method is functionally equivalent to:</p> 103114402Sru * <pre> 104114402Sru * newInstance(DEFAULT_OBJECT_MODEL_URI) 105114402Sru * </pre> 106114402Sru * 107114402Sru * <p>Since the implementation for the W3C DOM is always available, this method will never fail.</p> 108114402Sru * 109114402Sru * @return Instance of an {@code XPathFactory}. 110114402Sru * 111114402Sru * @throws RuntimeException When there is a failure in creating an 112114402Sru * {@code XPathFactory} for the default object model. 113114402Sru */ 114114402Sru public static XPathFactory newInstance() { 115114402Sru 116114402Sru try { 117114402Sru return newInstance(DEFAULT_OBJECT_MODEL_URI); 118114402Sru } catch (XPathFactoryConfigurationException e) { 119114402Sru throw new RuntimeException( 120114402Sru "XPathFactory#newInstance() failed to create an XPathFactory for the default object model: " 121114402Sru + DEFAULT_OBJECT_MODEL_URI 122114402Sru + " with the XPathFactoryConfigurationException: " 123114402Sru + e.getMessage(), e 124114402Sru ); 125114402Sru } 126114402Sru } 127114402Sru 128114402Sru /** 129114402Sru * <p>Get a new {@code XPathFactory} instance using the specified object model.</p> 130114402Sru * 131114402Sru * <p>To find a {@code XPathFactory} object, 132114402Sru * this method looks the following places in the following order where "the class loader" refers to the context class loader:</p> 133114402Sru * <ol> 134114402Sru * <li> 135114402Sru * <p> 136114402Sru * If the system property {@link #DEFAULT_PROPERTY_NAME} + ":uri" is present, 137114402Sru * where uri is the parameter to this method, then its value is read as a class name. 138114402Sru * The method will try to create a new instance of this class by using the class loader, 139114402Sru * and returns it if it is successfully created. 140114402Sru * </li> 141114402Sru * <li> 142114402Sru * <p> 143114402Sru * Use the configuration file "jaxp.properties". The file is in standard 144114402Sru * {@link java.util.Properties} format and typically located in the 145114402Sru * conf directory of the Java installation. It contains the fully qualified 146114402Sru * name of the implementation class with the key being the system property 147114402Sru * defined above. 148114402Sru * <p> 149114402Sru * The jaxp.properties file is read only once by the JAXP implementation 150114402Sru * and its values are then cached for future use. If the file does not exist 151114402Sru * when the first attempt is made to read from it, no further attempts are 152114402Sru * made to check for its existence. It is not possible to change the value 153114402Sru * of any property in jaxp.properties after it has been read for the first time. 154114402Sru * </li> 155114402Sru * <li> 156114402Sru * <p> 157114402Sru * Use the service-provider loading facility, defined by the 158114402Sru * {@link java.util.ServiceLoader} class, to attempt to locate and load an 159114402Sru * implementation of the service using the {@linkplain 160114402Sru * java.util.ServiceLoader#load(java.lang.Class) default loading mechanism}: 161114402Sru * the service-provider loading facility will use the {@linkplain 162114402Sru * java.lang.Thread#getContextClassLoader() current thread's context class loader} 163114402Sru * to attempt to load the service. If the context class 164114402Sru * loader is null, the {@linkplain 165114402Sru * ClassLoader#getSystemClassLoader() system class loader} will be used. 166114402Sru * <br> 167114402Sru * Each potential service provider is required to implement the method 168114402Sru * {@link #isObjectModelSupported(String objectModel)}. 169114402Sru * The first service provider found that supports the specified object 170114402Sru * model is returned. 171114402Sru * <br> 172114402Sru * In case of {@link java.util.ServiceConfigurationError} an 173114402Sru * {@link XPathFactoryConfigurationException} will be thrown. 174114402Sru * </li> 175114402Sru * <li> 176114402Sru * <p> 177114402Sru * Platform default {@code XPathFactory} is located in a platform 178114402Sru * specific way. 179114402Sru * There must be a {@linkplain #newDefaultInstance() platform default} 180114402Sru * {@code XPathFactory} for the W3C DOM, i.e. 181114402Sru * {@link #DEFAULT_OBJECT_MODEL_URI}. 182114402Sru * </li> 183114402Sru * </ol> 184114402Sru * <p>If everything fails, an {@code XPathFactoryConfigurationException} will be thrown. 185114402Sru * 186114402Sru * <p>Tip for Trouble-shooting: 187114402Sru * <p>See {@link java.util.Properties#load(java.io.InputStream)} for exactly how a property file is parsed. 188114402Sru * In particular, colons ':' need to be escaped in a property file, so make sure the URIs are properly escaped in it. 189114402Sru * For example: 190114402Sru * <pre> 191114402Sru * http\://java.sun.com/jaxp/xpath/dom=org.acme.DomXPathFactory 192114402Sru * </pre> 193114402Sru * 194114402Sru * @param uri Identifies the underlying object model. 195114402Sru * The specification only defines the URI {@link #DEFAULT_OBJECT_MODEL_URI}, 196114402Sru * <code>http://java.sun.com/jaxp/xpath/dom</code> for the W3C DOM, 197114402Sru * the org.w3c.dom package, and implementations are free to introduce other URIs for other object models. 198114402Sru * 199114402Sru * @return Instance of an {@code XPathFactory}. 200114402Sru * 201114402Sru * @throws XPathFactoryConfigurationException If the specified object model 202114402Sru * is unavailable, or if there is a configuration error. 203114402Sru * @throws NullPointerException If <code>uri</code> is <code>null</code>. 204114402Sru * @throws IllegalArgumentException If <code>uri</code> is <code>null</code> 205114402Sru * or <code>uri.length() == 0</code>. 206114402Sru */ 207114402Sru public static XPathFactory newInstance(final String uri) 208114402Sru throws XPathFactoryConfigurationException { 209114402Sru 210114402Sru if (uri == null) { 211114402Sru throw new NullPointerException( 212114402Sru "XPathFactory#newInstance(String uri) cannot be called with uri == null"); 213114402Sru } 214114402Sru 215114402Sru if (uri.length() == 0) { 216114402Sru throw new IllegalArgumentException( 217114402Sru "XPathFactory#newInstance(String uri) cannot be called with uri == \"\""); 218114402Sru } 219114402Sru 220114402Sru ClassLoader classLoader = ss.getContextClassLoader(); 221114402Sru 222114402Sru if (classLoader == null) { 223114402Sru //use the current class loader 224114402Sru classLoader = XPathFactory.class.getClassLoader(); 225114402Sru } 226114402Sru 227114402Sru XPathFactory xpathFactory = new XPathFactoryFinder(classLoader).newFactory(uri); 228114402Sru 229114402Sru if (xpathFactory == null) { 230114402Sru throw new XPathFactoryConfigurationException( 231114402Sru "No XPathFactory implementation found for the object model: " 232114402Sru + uri); 233114402Sru } 234114402Sru 235114402Sru return xpathFactory; 236114402Sru } 237114402Sru 238114402Sru /** 239114402Sru * <p>Obtain a new instance of a {@code XPathFactory} from a factory class name. {@code XPathFactory} 240114402Sru * is returned if specified factory class supports the specified object model. 241114402Sru * This function is useful when there are multiple providers in the classpath. 242114402Sru * It gives more control to the application as it can specify which provider 243114402Sru * should be loaded.</p> 244114402Sru * 245114402Sru * 246114402Sru * <h2>Tip for Trouble-shooting</h2> 247114402Sru * <p>Setting the <code>jaxp.debug</code> system property will cause 248114402Sru * this method to print a lot of debug messages 249114402Sru * to <code>System.err</code> about what it is doing and where it is looking at.</p> 250114402Sru * 251114402Sru * <p> If you have problems try:</p> 252114402Sru * <pre> 253114402Sru * java -Djaxp.debug=1 YourProgram .... 254114402Sru * </pre> 255114402Sru * 256114402Sru * @param uri Identifies the underlying object model. The specification only defines the URI 257114402Sru * {@link #DEFAULT_OBJECT_MODEL_URI},<code>http://java.sun.com/jaxp/xpath/dom</code> 258114402Sru * for the W3C DOM, the org.w3c.dom package, and implementations are free to introduce 259114402Sru * other URIs for other object models. 260114402Sru * 261114402Sru * @param factoryClassName fully qualified factory class name that provides implementation of <code>javax.xml.xpath.XPathFactory</code>. 262114402Sru * 263114402Sru * @param classLoader <code>ClassLoader</code> used to load the factory class. If <code>null</code> 264114402Sru * current <code>Thread</code>'s context classLoader is used to load the factory class. 265114402Sru * 266114402Sru * 267114402Sru * @return New instance of a {@code XPathFactory} 268114402Sru * 269114402Sru * @throws XPathFactoryConfigurationException 270114402Sru * if <code>factoryClassName</code> is <code>null</code>, or 271114402Sru * the factory class cannot be loaded, instantiated 272114402Sru * or the factory class does not support the object model specified 273114402Sru * in the <code>uri</code> parameter. 274114402Sru * 275114402Sru * @throws NullPointerException If <code>uri</code> is <code>null</code>. 276114402Sru * @throws IllegalArgumentException If <code>uri</code> is <code>null</code> 277114402Sru * or <code>uri.length() == 0</code>. 278114402Sru * 279114402Sru * @see #newInstance() 280114402Sru * @see #newInstance(String uri) 281114402Sru * 282114402Sru * @since 1.6 283114402Sru */ 284114402Sru public static XPathFactory newInstance(String uri, String factoryClassName, ClassLoader classLoader) 285114402Sru throws XPathFactoryConfigurationException{ 286114402Sru ClassLoader cl = classLoader; 287114402Sru 288114402Sru if (uri == null) { 289114402Sru throw new NullPointerException( 290114402Sru "XPathFactory#newInstance(String uri) cannot be called with uri == null"); 291114402Sru } 292114402Sru 293114402Sru if (uri.length() == 0) { 294114402Sru throw new IllegalArgumentException( 295114402Sru "XPathFactory#newInstance(String uri) cannot be called with uri == \"\""); 296114402Sru } 297114402Sru 298114402Sru if (cl == null) { 299114402Sru cl = ss.getContextClassLoader(); 300114402Sru } 301114402Sru 302114402Sru XPathFactory f = new XPathFactoryFinder(cl).createInstance(factoryClassName); 303114402Sru 304114402Sru if (f == null) { 305114402Sru throw new XPathFactoryConfigurationException( 306114402Sru "No XPathFactory implementation found for the object model: " 307114402Sru + uri); 308114402Sru } 309114402Sru //if this factory supports the given schemalanguage return this factory else thrown exception 310114402Sru if (f.isObjectModelSupported(uri)) { 311114402Sru return f; 312114402Sru } else { 313114402Sru throw new XPathFactoryConfigurationException("Factory " 314114402Sru + factoryClassName + " doesn't support given " + uri 315114402Sru + " object model"); 316114402Sru } 317114402Sru 318114402Sru } 319114402Sru 320114402Sru /** 321114402Sru * <p>Is specified object model supported by this {@code XPathFactory}?</p> 322114402Sru * 323114402Sru * @param objectModel Specifies the object model which the returned {@code XPathFactory} will understand. 324114402Sru * 325114402Sru * @return <code>true</code> if {@code XPathFactory} supports <code>objectModel</code>, else <code>false</code>. 326114402Sru * 327114402Sru * @throws NullPointerException If <code>objectModel</code> is <code>null</code>. 328114402Sru * @throws IllegalArgumentException If <code>objectModel.length() == 0</code>. 329114402Sru */ 330114402Sru public abstract boolean isObjectModelSupported(String objectModel); 331114402Sru 332114402Sru /** 333114402Sru * <p>Set a feature for this {@code XPathFactory} and 334114402Sru * <code>XPath</code>s created by this factory.</p> 335114402Sru * 336114402Sru * <p> 337114402Sru * Feature names are fully qualified {@link java.net.URI}s. 338114402Sru * Implementations may define their own features. 339114402Sru * An {@link XPathFactoryConfigurationException} is thrown if this 340114402Sru * {@code XPathFactory} or the <code>XPath</code>s 341114402Sru * it creates cannot support the feature. 342114402Sru * It is possible for an {@code XPathFactory} to expose a feature value 343114402Sru * but be unable to change its state. 344114402Sru * </p> 345114402Sru * 346114402Sru * <p> 347114402Sru * All implementations are required to support the {@link javax.xml.XMLConstants#FEATURE_SECURE_PROCESSING} feature. 348114402Sru * When the feature is <code>true</code>, any reference to an external function is an error. 349114402Sru * Under these conditions, the implementation must not call the {@link XPathFunctionResolver} 350114402Sru * and must throw an {@link XPathFunctionException}. 351114402Sru * </p> 352114402Sru * 353114402Sru * @param name Feature name. 354114402Sru * @param value Is feature state <code>true</code> or <code>false</code>. 355114402Sru * 356114402Sru * @throws XPathFactoryConfigurationException if this {@code XPathFactory} or the <code>XPath</code>s 357114402Sru * it creates cannot support this feature. 358114402Sru * @throws NullPointerException if <code>name</code> is <code>null</code>. 359114402Sru */ 360114402Sru public abstract void setFeature(String name, boolean value) 361114402Sru throws XPathFactoryConfigurationException; 362114402Sru 363114402Sru /** 364114402Sru * <p>Get the state of the named feature.</p> 365114402Sru * 366114402Sru * <p> 367114402Sru * Feature names are fully qualified {@link java.net.URI}s. 368114402Sru * Implementations may define their own features. 369114402Sru * An {@link XPathFactoryConfigurationException} is thrown if this 370114402Sru * {@code XPathFactory} or the <code>XPath</code>s 371114402Sru * it creates cannot support the feature. 372114402Sru * It is possible for an {@code XPathFactory} to expose a feature value 373114402Sru * but be unable to change its state. 374114402Sru * </p> 375114402Sru * 376114402Sru * @param name Feature name. 377114402Sru * 378114402Sru * @return State of the named feature. 379114402Sru * 380114402Sru * @throws XPathFactoryConfigurationException if this 381114402Sru * {@code XPathFactory} or the <code>XPath</code>s 382114402Sru * it creates cannot support this feature. 383114402Sru * @throws NullPointerException if <code>name</code> is <code>null</code>. 384114402Sru */ 385114402Sru public abstract boolean getFeature(String name) 386114402Sru throws XPathFactoryConfigurationException; 387114402Sru 388114402Sru /** 389114402Sru * <p>Establish a default variable resolver.</p> 390114402Sru * 391114402Sru * <p>Any <code>XPath</code> objects constructed from this factory will use 392114402Sru * the specified resolver by default.</p> 393114402Sru * 394114402Sru * <p>A <code>NullPointerException</code> is thrown if <code>resolver</code> 395114402Sru * is <code>null</code>.</p> 396114402Sru * 397114402Sru * @param resolver Variable resolver. 398114402Sru * 399114402Sru * @throws NullPointerException If <code>resolver</code> is 400114402Sru * <code>null</code>. 401114402Sru */ 402114402Sru public abstract void setXPathVariableResolver(XPathVariableResolver resolver); 403114402Sru 404114402Sru /** 405114402Sru * <p>Establish a default function resolver.</p> 406114402Sru * 407114402Sru * <p>Any <code>XPath</code> objects constructed from this factory will 408114402Sru * use the specified resolver by default.</p> 409114402Sru * 410114402Sru * <p>A <code>NullPointerException</code> is thrown if 411114402Sru * <code>resolver</code> is <code>null</code>.</p> 412114402Sru * 413114402Sru * @param resolver XPath function resolver. 414114402Sru * 415114402Sru * @throws NullPointerException If <code>resolver</code> is 416114402Sru * <code>null</code>. 417114402Sru */ 418114402Sru public abstract void setXPathFunctionResolver(XPathFunctionResolver resolver); 419114402Sru 420114402Sru /** 421114402Sru * <p>Return a new <code>XPath</code> using the underlying object 422114402Sru * model determined when the {@code XPathFactory} was instantiated.</p> 423114402Sru * 424114402Sru * @return New instance of an <code>XPath</code>. 425114402Sru */ 426114402Sru public abstract XPath newXPath(); 427114402Sru} 428114402Sru