src/javax/xml/stream/FactoryFinder.java

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rev 406 : 8005954: JAXP Plugability Layer should use java.util.ServiceLoader
Summary: This fix replaces manual processing of files under META-INF/services in JAXP factories by calls to java.util.ServiceLoader.
Reviewed-by: alanb, joehw, mchung
   1 /*
   2  * Copyright (c) 2005, 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  *
  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.stream;
  27 
  28 import java.io.BufferedReader;
  29 import java.io.File;
  30 import java.io.IOException;
  31 import java.io.InputStream;
  32 import java.io.InputStreamReader;
  33 import java.util.Properties;


  34 
  35 /**
  36  * <p>Implements pluggable Datatypes.</p>
  37  *
  38  * <p>This class is duplicated for each JAXP subpackage so keep it in
  39  * sync.  It is package private for secure class loading.</p>
  40  *
  41  * @author Santiago.PericasGeertsen@sun.com
  42  */
  43 class FactoryFinder {
  44     // Check we have access to package.
  45     private static final String DEFAULT_PACKAGE = "com.sun.xml.internal.";
  46 
  47     /**
  48      * Internal debug flag.
  49      */
  50     private static boolean debug = false;
  51 
  52     /**
  53      * Cache for properties in java.home/lib/jaxp.properties
  54      */
  55     static Properties cacheProps = new Properties();
  56 
  57     /**
  58      * Flag indicating if properties from java.home/lib/jaxp.properties
  59      * have been cached.
  60      */
  61     static volatile boolean firstTime = true;
  62 
  63     /**
  64      * Security support class use to check access control before
  65      * getting certain system resources.
  66      */
  67     static SecuritySupport ss = new SecuritySupport();
  68 
  69     // Define system property "jaxp.debug" to get output
  70     static {
  71         // Use try/catch block to support applets, which throws
  72         // SecurityException out of this code.
  73         try {
  74             String val = ss.getSystemProperty("jaxp.debug");
  75             // Allow simply setting the prop to turn on debug
  76             debug = val != null && !"false".equals(val);
  77         }
  78         catch (SecurityException se) {
  79             debug = false;
  80         }
  81     }
  82 
  83     private static void dPrint(String msg) {
  84         if (debug) {
  85             System.err.println("JAXP: " + msg);
  86         }
  87     }
  88 
  89     /**
  90      * Attempt to load a class using the class loader supplied. If that fails
  91      * and fall back is enabled, the current (i.e. bootstrap) class loader is
  92      * tried.
  93      *
  94      * If the class loader supplied is <code>null</code>, first try using the
  95      * context class loader followed by the current (i.e. bootstrap) class
  96      * loader.
  97      *
  98      * Use bootstrap classLoader if cl = null and useBSClsLoader is true
  99      */
 100     static private Class getProviderClass(String className, ClassLoader cl,
 101             boolean doFallback, boolean useBSClsLoader) throws ClassNotFoundException
 102     {
 103         try {
 104             if (cl == null) {
 105                 if (useBSClsLoader) {
 106                     return Class.forName(className, true, FactoryFinder.class.getClassLoader());
 107                 } else {
 108                     cl = ss.getContextClassLoader();
 109                     if (cl == null) {
 110                         throw new ClassNotFoundException();
 111                     }
 112                     else {
 113                         return cl.loadClass(className);
 114                     }
 115                 }
 116             }
 117             else {
 118                 return cl.loadClass(className);
 119             }
 120         }
 121         catch (ClassNotFoundException e1) {
 122             if (doFallback) {
 123                 // Use current class loader - should always be bootstrap CL
 124                 return Class.forName(className, true, FactoryFinder.class.getClassLoader());
 125             }
 126             else {
 127                 throw e1;
 128             }
 129         }
 130     }
 131 
 132     /**
 133      * Create an instance of a class. Delegates to method
 134      * <code>getProviderClass()</code> in order to load the class.
 135      *



 136      * @param className Name of the concrete class corresponding to the
 137      * service provider
 138      *
 139      * @param cl <code>ClassLoader</code> used to load the factory class. If <code>null</code>
 140      * current <code>Thread</code>'s context classLoader is used to load the factory class.
 141      *
 142      * @param doFallback True if the current ClassLoader should be tried as
 143      * a fallback if the class is not found using cl
 144      */
 145     static Object newInstance(String className, ClassLoader cl, boolean doFallback)
 146         throws ConfigurationError
 147     {
 148         return newInstance(className, cl, doFallback, false);
 149     }
 150 
 151     /**
 152      * Create an instance of a class. Delegates to method
 153      * <code>getProviderClass()</code> in order to load the class.
 154      *



 155      * @param className Name of the concrete class corresponding to the
 156      * service provider
 157      *
 158      * @param cl <code>ClassLoader</code> used to load the factory class. If <code>null</code>
 159      * current <code>Thread</code>'s context classLoader is used to load the factory class.
 160      *
 161      * @param doFallback True if the current ClassLoader should be tried as
 162      * a fallback if the class is not found using cl
 163      *
 164      * @param useBSClsLoader True if cl=null actually meant bootstrap classLoader. This parameter
 165      * is needed since DocumentBuilderFactory/SAXParserFactory defined null as context classLoader.
 166      */
 167     static Object newInstance(String className, ClassLoader cl, boolean doFallback, boolean useBSClsLoader)
 168         throws ConfigurationError

 169     {


 170         // make sure we have access to restricted packages
 171         if (System.getSecurityManager() != null) {
 172             if (className != null && className.startsWith(DEFAULT_PACKAGE)) {
 173                 cl = null;
 174                 useBSClsLoader = true;
 175             }
 176         }
 177 
 178         try {
 179             Class providerClass = getProviderClass(className, cl, doFallback, useBSClsLoader);



 180             Object instance = providerClass.newInstance();
 181             if (debug) {    // Extra check to avoid computing cl strings
 182                 dPrint("created new instance of " + providerClass +
 183                        " using ClassLoader: " + cl);
 184             }
 185             return instance;
 186         }
 187         catch (ClassNotFoundException x) {
 188             throw new ConfigurationError(
 189                 "Provider " + className + " not found", x);
 190         }
 191         catch (Exception x) {
 192             throw new ConfigurationError(
 193                 "Provider " + className + " could not be instantiated: " + x,
 194                 x);
 195         }
 196     }
 197 
 198     /**
 199      * Finds the implementation Class object in the specified order.
 200      *
 201      * @return Class object of factory, never null
 202      *
 203      * @param factoryId             Name of the factory to find, same as
 204      *                              a property name

 205      * @param fallbackClassName     Implementation class name, if nothing else
 206      *                              is found.  Use null to mean no fallback.
 207      *
 208      * Package private so this code can be shared.
 209      */
 210     static Object find(String factoryId, String fallbackClassName)
 211         throws ConfigurationError
 212     {
 213         return find(factoryId, null, fallbackClassName);
 214     }
 215 
 216     /**
 217      * Finds the implementation Class object in the specified order.  Main
 218      * entry point.
 219      * @return Class object of factory, never null
 220      *



 221      * @param factoryId             Name of the factory to find, same as
 222      *                              a property name
 223      *
 224      * @param cl                    ClassLoader to be used to load the class, null means to use
 225      * the bootstrap ClassLoader
 226      *
 227      * @param fallbackClassName     Implementation class name, if nothing else
 228      *                              is found.  Use null to mean no fallback.
 229      *
 230      * Package private so this code can be shared.
 231      */
 232     static Object find(String factoryId, ClassLoader cl, String fallbackClassName)
 233         throws ConfigurationError
 234     {
 235         dPrint("find factoryId =" + factoryId);
 236 
 237         // Use the system property first
 238         try {
 239             String systemProp = ss.getSystemProperty(factoryId);
 240             if (systemProp != null) {
 241                 dPrint("found system property, value=" + systemProp);
 242                 return newInstance(systemProp, null, true);


 243             }
 244         }
 245         catch (SecurityException se) {
 246             if (debug) se.printStackTrace();
 247         }
 248 
 249         // Try read $java.home/lib/stax.properties followed by
 250         // $java.home/lib/jaxp.properties if former not present
 251         String configFile = null;
 252         try {
 253             String factoryClassName = null;
 254             if (firstTime) {
 255                 synchronized (cacheProps) {
 256                     if (firstTime) {
 257                         configFile = ss.getSystemProperty("java.home") + File.separator +
 258                             "lib" + File.separator + "stax.properties";
 259                         File f = new File(configFile);
 260                         firstTime = false;
 261                         if (ss.doesFileExist(f)) {
 262                             dPrint("Read properties file "+f);
 263                             cacheProps.load(ss.getFileInputStream(f));
 264                         }
 265                         else {
 266                             configFile = ss.getSystemProperty("java.home") + File.separator +
 267                                 "lib" + File.separator + "jaxp.properties";
 268                             f = new File(configFile);
 269                             if (ss.doesFileExist(f)) {
 270                                 dPrint("Read properties file "+f);
 271                                 cacheProps.load(ss.getFileInputStream(f));
 272                     }
 273                 }
 274             }
 275                 }
 276             }
 277             factoryClassName = cacheProps.getProperty(factoryId);
 278 
 279             if (factoryClassName != null) {
 280                 dPrint("found in " + configFile + " value=" + factoryClassName);
 281                 return newInstance(factoryClassName, null, true);


 282             }
 283         }
 284         catch (Exception ex) {
 285             if (debug) ex.printStackTrace();
 286         }
 287 

 288         // Try Jar Service Provider Mechanism
 289         Object provider = findJarServiceProvider(factoryId);
 290         if (provider != null) {
 291             return provider;
 292         }






 293         if (fallbackClassName == null) {
 294             throw new ConfigurationError(
 295                 "Provider for " + factoryId + " cannot be found", null);
 296         }
 297 
 298         dPrint("loaded from fallback value: " + fallbackClassName);
 299         return newInstance(fallbackClassName, cl, true);
 300     }
 301 
 302     /*
 303      * Try to find provider using Jar Service Provider Mechanism


 304      *
 305      * @return instance of provider class if found or null
 306      */
 307     private static Object findJarServiceProvider(String factoryId)
 308         throws ConfigurationError
 309     {
 310         String serviceId = "META-INF/services/" + factoryId;
 311         InputStream is = null;
 312 
 313         // First try the Context ClassLoader
 314         ClassLoader cl = ss.getContextClassLoader();
 315         boolean useBSClsLoader = false;
 316         if (cl != null) {
 317             is = ss.getResourceAsStream(cl, serviceId);
 318 
 319             // If no provider found then try the current ClassLoader
 320             if (is == null) {
 321                 cl = FactoryFinder.class.getClassLoader();
 322                 is = ss.getResourceAsStream(cl, serviceId);
 323                 useBSClsLoader = true;
 324             }
 325         } else {
 326             // No Context ClassLoader, try the current ClassLoader
 327             cl = FactoryFinder.class.getClassLoader();
 328             is = ss.getResourceAsStream(cl, serviceId);
 329             useBSClsLoader = true;
 330         }
 331 
 332         if (is == null) {
 333             // No provider found
 334             return null;
 335         }
 336 
 337         if (debug) {    // Extra check to avoid computing cl strings
 338             dPrint("found jar resource=" + serviceId + " using ClassLoader: " + cl);
 339         }
 340 
 341         BufferedReader rd;
 342         try {
 343             rd = new BufferedReader(new InputStreamReader(is, "UTF-8"));
 344         }
 345         catch (java.io.UnsupportedEncodingException e) {
 346             rd = new BufferedReader(new InputStreamReader(is));
 347         }
 348 
 349         String factoryClassName = null;
 350         try {
 351             // XXX Does not handle all possible input as specified by the
 352             // Jar Service Provider specification
 353             factoryClassName = rd.readLine();
 354             rd.close();
 355         } catch (IOException x) {
 356             // No provider found
 357             return null;
 358         }
 359 
 360         if (factoryClassName != null && !"".equals(factoryClassName)) {
 361             dPrint("found in resource, value=" + factoryClassName);
 362 
 363             // Note: here we do not want to fall back to the current
 364             // ClassLoader because we want to avoid the case where the
 365             // resource file was found using one ClassLoader and the
 366             // provider class was instantiated using a different one.
 367             return newInstance(factoryClassName, cl, false, useBSClsLoader);
 368         }
 369 
 370         // No provider found
 371         return null;
 372     }
 373 
 374     static class ConfigurationError extends Error {
 375         private Exception exception;
 376 
 377         /**
 378          * Construct a new instance with the specified detail string and
 379          * exception.
 380          */
 381         ConfigurationError(String msg, Exception x) {
 382             super(msg);
 383             this.exception = x;
 384         }
 385 
 386         Exception getException() {
 387             return exception;
 388         }
 389         /**
 390         * use the exception chaining mechanism of JDK1.4
 391         */
 392         @Override
 393         public Throwable getCause() {
 394             return exception;




 395         }
 396     }
 397 
 398 }
   1 /*
   2  * Copyright (c) 2005, 2013, 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.stream;
  27 

  28 import java.io.File;
  29 import java.security.AccessController;
  30 import java.security.PrivilegedAction;
  31 import java.util.Iterator;
  32 import java.util.Properties;
  33 import java.util.ServiceConfigurationError;
  34 import java.util.ServiceLoader;
  35 
  36 /**
  37  * <p>Implements pluggable streams.</p>
  38  *
  39  * <p>This class is duplicated for each JAXP subpackage so keep it in
  40  * sync.  It is package private for secure class loading.</p>
  41  *
  42  * @author Santiago.PericasGeertsen@sun.com
  43  */
  44 class FactoryFinder {
  45     // Check we have access to package.
  46     private static final String DEFAULT_PACKAGE = "com.sun.xml.internal.";
  47 
  48     /**
  49      * Internal debug flag.
  50      */
  51     private static boolean debug = false;
  52 
  53     /**
  54      * Cache for properties in java.home/lib/jaxp.properties
  55      */
  56     final private static Properties cacheProps = new Properties();
  57 
  58     /**
  59      * Flag indicating if properties from java.home/lib/jaxp.properties
  60      * have been cached.
  61      */
  62     private static volatile boolean firstTime = true;
  63 
  64     /**
  65      * Security support class use to check access control before
  66      * getting certain system resources.
  67      */
  68     final private static SecuritySupport ss = new SecuritySupport();
  69 
  70     // Define system property "jaxp.debug" to get output
  71     static {
  72         // Use try/catch block to support applets, which throws
  73         // SecurityException out of this code.
  74         try {
  75             String val = ss.getSystemProperty("jaxp.debug");
  76             // Allow simply setting the prop to turn on debug
  77             debug = val != null && !"false".equals(val);
  78         }
  79         catch (SecurityException se) {
  80             debug = false;
  81         }
  82     }
  83 
  84     private static void dPrint(String msg) {
  85         if (debug) {
  86             System.err.println("JAXP: " + msg);
  87         }
  88     }
  89 
  90     /**
  91      * Attempt to load a class using the class loader supplied. If that fails
  92      * and fall back is enabled, the current (i.e. bootstrap) class loader is
  93      * tried.
  94      *
  95      * If the class loader supplied is <code>null</code>, first try using the
  96      * context class loader followed by the current (i.e. bootstrap) class
  97      * loader.
  98      *
  99      * Use bootstrap classLoader if cl = null and useBSClsLoader is true
 100      */
 101     static private Class getProviderClass(String className, ClassLoader cl,
 102             boolean doFallback, boolean useBSClsLoader) throws ClassNotFoundException
 103     {
 104         try {
 105             if (cl == null) {
 106                 if (useBSClsLoader) {
 107                     return Class.forName(className, false, FactoryFinder.class.getClassLoader());
 108                 } else {
 109                     cl = ss.getContextClassLoader();
 110                     if (cl == null) {
 111                         throw new ClassNotFoundException();
 112                     }
 113                     else {
 114                         return Class.forName(className, false, cl);
 115                     }
 116                 }
 117             }
 118             else {
 119                 return Class.forName(className, false, cl);
 120             }
 121         }
 122         catch (ClassNotFoundException e1) {
 123             if (doFallback) {
 124                 // Use current class loader - should always be bootstrap CL
 125                 return Class.forName(className, false, FactoryFinder.class.getClassLoader());
 126             }
 127             else {
 128                 throw e1;
 129             }
 130         }
 131     }
 132 
 133     /**
 134      * Create an instance of a class. Delegates to method
 135      * <code>getProviderClass()</code> in order to load the class.
 136      *
 137      * @param type Base class / Service interface  of the factory to
 138      *             instantiate.
 139      *
 140      * @param className Name of the concrete class corresponding to the
 141      * service provider
 142      *
 143      * @param cl <code>ClassLoader</code> used to load the factory class. If <code>null</code>
 144      * current <code>Thread</code>'s context classLoader is used to load the factory class.
 145      *
 146      * @param doFallback True if the current ClassLoader should be tried as
 147      * a fallback if the class is not found using cl
 148      */
 149     static <T> T newInstance(Class<T> type, String className, ClassLoader cl, boolean doFallback)
 150         throws FactoryConfigurationError
 151     {
 152         return newInstance(type, className, cl, doFallback, false);
 153     }
 154 
 155     /**
 156      * Create an instance of a class. Delegates to method
 157      * <code>getProviderClass()</code> in order to load the class.
 158      *
 159      * @param type Base class / Service interface  of the factory to
 160      *             instantiate.
 161      *
 162      * @param className Name of the concrete class corresponding to the
 163      * service provider
 164      *
 165      * @param cl <code>ClassLoader</code> used to load the factory class. If <code>null</code>
 166      * current <code>Thread</code>'s context classLoader is used to load the factory class.
 167      *
 168      * @param doFallback True if the current ClassLoader should be tried as
 169      * a fallback if the class is not found using cl
 170      *
 171      * @param useBSClsLoader True if cl=null actually meant bootstrap classLoader. This parameter
 172      * is needed since DocumentBuilderFactory/SAXParserFactory defined null as context classLoader.
 173      */
 174     static <T> T newInstance(Class<T> type, String className, ClassLoader cl,
 175                               boolean doFallback, boolean useBSClsLoader)
 176         throws FactoryConfigurationError
 177     {
 178         assert type != null;
 179 
 180         // make sure we have access to restricted packages
 181         if (System.getSecurityManager() != null) {
 182             if (className != null && className.startsWith(DEFAULT_PACKAGE)) {
 183                 cl = null;
 184                 useBSClsLoader = true;
 185             }
 186         }
 187 
 188         try {
 189             Class<?> providerClass = getProviderClass(className, cl, doFallback, useBSClsLoader);
 190             if (!type.isAssignableFrom(providerClass)) {
 191                 throw new ClassCastException(className + " cannot be cast to " + type.getName());
 192             }
 193             Object instance = providerClass.newInstance();
 194             if (debug) {    // Extra check to avoid computing cl strings
 195                 dPrint("created new instance of " + providerClass +
 196                        " using ClassLoader: " + cl);
 197             }
 198             return type.cast(instance);
 199         }
 200         catch (ClassNotFoundException x) {
 201             throw new FactoryConfigurationError(
 202                 "Provider " + className + " not found", x);
 203         }
 204         catch (Exception x) {
 205             throw new FactoryConfigurationError(
 206                 "Provider " + className + " could not be instantiated: " + x,
 207                 x);
 208         }
 209     }
 210 
 211     /**
 212      * Finds the implementation Class object in the specified order.
 213      *
 214      * @return Class object of factory, never null
 215      *
 216      * @param type                  Base class / Service interface  of the
 217      *                              factory to find.
 218      *
 219      * @param fallbackClassName     Implementation class name, if nothing else
 220      *                              is found.  Use null to mean no fallback.
 221      *
 222      * Package private so this code can be shared.
 223      */
 224     static <T> T find(Class<T> type, String fallbackClassName)
 225         throws FactoryConfigurationError
 226     {
 227         return find(type, type.getName(), null, fallbackClassName);
 228     }
 229 
 230     /**
 231      * Finds the implementation Class object in the specified order.  Main
 232      * entry point.
 233      * @return Class object of factory, never null
 234      *
 235      * @param type                  Base class / Service interface  of the
 236      *                              factory to find.
 237      *
 238      * @param factoryId             Name of the factory to find, same as
 239      *                              a property name
 240      *
 241      * @param cl                    ClassLoader to be used to load the class, null means to use
 242      * the bootstrap ClassLoader
 243      *
 244      * @param fallbackClassName     Implementation class name, if nothing else
 245      *                              is found.  Use null to mean no fallback.
 246      *
 247      * Package private so this code can be shared.
 248      */
 249     static <T> T find(Class<T> type, String factoryId, ClassLoader cl, String fallbackClassName)
 250         throws FactoryConfigurationError
 251     {
 252         dPrint("find factoryId =" + factoryId);
 253 
 254         // Use the system property first
 255         try {
 256             String systemProp = ss.getSystemProperty(factoryId);
 257             if (systemProp != null) {
 258                 dPrint("found system property, value=" + systemProp);
 259                 // There's a bug here - because 'cl' is ignored.
 260                 // This will be handled separately.
 261                 return newInstance(type, systemProp, null, true);
 262             }
 263         }
 264         catch (SecurityException se) {
 265             if (debug) se.printStackTrace();
 266         }
 267 
 268         // Try read $java.home/lib/stax.properties followed by
 269         // $java.home/lib/jaxp.properties if former not present
 270         String configFile = null;
 271         try {

 272             if (firstTime) {
 273                 synchronized (cacheProps) {
 274                     if (firstTime) {
 275                         configFile = ss.getSystemProperty("java.home") + File.separator +
 276                             "lib" + File.separator + "stax.properties";
 277                         File f = new File(configFile);
 278                         firstTime = false;
 279                         if (ss.doesFileExist(f)) {
 280                             dPrint("Read properties file "+f);
 281                             cacheProps.load(ss.getFileInputStream(f));
 282                         }
 283                         else {
 284                             configFile = ss.getSystemProperty("java.home") + File.separator +
 285                                 "lib" + File.separator + "jaxp.properties";
 286                             f = new File(configFile);
 287                             if (ss.doesFileExist(f)) {
 288                                 dPrint("Read properties file "+f);
 289                                 cacheProps.load(ss.getFileInputStream(f));
 290                             }
 291                         }
 292                     }
 293                 }
 294             }
 295             final String factoryClassName = cacheProps.getProperty(factoryId);
 296 
 297             if (factoryClassName != null) {
 298                 dPrint("found in " + configFile + " value=" + factoryClassName);
 299                 // There's a bug here - because 'cl' is ignored.
 300                 // This will be handled separately.
 301                 return newInstance(type, factoryClassName, null, true);
 302             }
 303         }
 304         catch (Exception ex) {
 305             if (debug) ex.printStackTrace();
 306         }
 307 
 308         if (type.getName().equals(factoryId)) {
 309             // Try Jar Service Provider Mechanism
 310             final T provider = findServiceProvider(type);
 311             if (provider != null) {
 312                 return provider;
 313             }
 314         } else {
 315             // We're in the case where a 'custom' factoryId was provided,
 316             // and in every case where that happens, we expect that
 317             // fallbackClassName will be null.
 318             assert fallbackClassName == null;
 319         }
 320         if (fallbackClassName == null) {
 321             throw new FactoryConfigurationError(
 322                 "Provider for " + factoryId + " cannot be found", null);
 323         }
 324 
 325         dPrint("loaded from fallback value: " + fallbackClassName);
 326         return newInstance(type, fallbackClassName, cl, true);
 327     }
 328 
 329     /*
 330      * Try to find provider using the ServiceLoader API
 331      *
 332      * @param type Base class / Service interface  of the factory to find.
 333      *
 334      * @return instance of provider class if found or null
 335      */
 336     private static <T> T findServiceProvider(final Class<T> type) {










































 337         try {
 338             return AccessController.doPrivileged(new PrivilegedAction<T>() {
 339                 @Override
 340                 public T run() {
 341                     final ServiceLoader<T> serviceLoader = ServiceLoader.load(type);
 342                     final Iterator<T> iterator = serviceLoader.iterator();
 343                     if (iterator.hasNext()) {
 344                         return iterator.next();
 345                     } else {












 346                         return null;
 347                     }











 348                 }
 349             });
 350         } catch(ServiceConfigurationError e) {
 351             // It is not possible to wrap an error directly in
 352             // FactoryConfigurationError - so we need to wrap the
 353             // ServiceConfigurationError in a RuntimeException.
 354             // The alternative would be to modify the logic in
 355             // FactoryConfigurationError to allow setting a
 356             // Throwable as the cause, but that could cause
 357             // compatibility issues down the road.
 358             final RuntimeException x = new RuntimeException(
 359                     "Provider for " + type + " cannot be created", e);
 360             final FactoryConfigurationError error =
 361                     new FactoryConfigurationError(x, x.getMessage());
 362             throw error;
 363           }
 364       }
 365 
 366 }