/* * Licensed to the Apache Software Foundation (ASF) under one or more * contributor license agreements.  See the NOTICE file distributed with * this work for additional information regarding copyright ownership. * The ASF licenses this file to You under the Apache License, Version 2.0 * (the "License"); you may not use this file except in compliance with * the License.  You may obtain a copy of the License at *  *      http://www.apache.org/licenses/LICENSE-2.0 *  * Unless required by applicable law or agreed to in writing, software * distributed under the License is distributed on an "AS IS" BASIS, * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. * See the License for the specific language governing permissions and * limitations under the License. */package org.apache.log4j.helpers;import java.net.URL;import java.lang.IllegalAccessException;import java.lang.reflect.Method;import java.lang.reflect.InvocationTargetException;/**   Load resources (or images) from various sources.   @author Ceki G&uuml;lc&uuml; */public class Loader  {   static final String TSTR = "Caught Exception while in Loader.getResource. This may be innocuous.";  // We conservatively assume that we are running under Java 1.x  static private boolean java1 = true;    static private boolean ignoreTCL = false;    static {    String prop = OptionConverter.getSystemProperty("java.version", null);        if(prop != null) {      int i = prop.indexOf('.');      if(i != -1) {		if(prop.charAt(i+1) != '1')	  java1 = false;      }     }    String ignoreTCLProp = OptionConverter.getSystemProperty("log4j.ignoreTCL", null);    if(ignoreTCLProp != null) {      ignoreTCL = OptionConverter.toBoolean(ignoreTCLProp, true);          }     }    /**   *  Get a resource by delegating to getResource(String).   *  @param resource resource name   *  @param clazz class, ignored.   *  @return URL to resource or null.   *  @deprecated as of 1.2.   */  public static URL getResource(String resource, Class clazz) {      return getResource(resource);  }  /**     This method will search for <code>resource</code> in different     places. The search order is as follows:     <ol>     <p><li>Search for <code>resource</code> using the thread context     class loader under Java2. If that fails, search for     <code>resource</code> using the class loader that loaded this     class (<code>Loader</code>). Under JDK 1.1, only the the class     loader that loaded this class (<code>Loader</code>) is used.     <p><li>Try one last time with     <code>ClassLoader.getSystemResource(resource)</code>, that is is     using the system class loader in JDK 1.2 and virtual machine's     built-in class loader in JDK 1.1.     </ol>  */  static public URL getResource(String resource) {    ClassLoader classLoader = null;    URL url = null;        try {  	if(!java1) {  	  classLoader = getTCL();  	  if(classLoader != null) {  	    LogLog.debug("Trying to find ["+resource+"] using context classloader "  			 +classLoader+".");  	    url = classLoader.getResource(resource);        	    if(url != null) {  	      return url;  	    }  	  }  	}  	  	// We could not find resource. Ler us now try with the  	// classloader that loaded this class.  	classLoader = Loader.class.getClassLoader();   	if(classLoader != null) {  	  LogLog.debug("Trying to find ["+resource+"] using "+classLoader  		       +" class loader.");  	  url = classLoader.getResource(resource);  	  if(url != null) {  	    return url;  	  }  	}    } catch(Throwable t) {  	LogLog.warn(TSTR, t);    }        // Last ditch attempt: get the resource from the class path. It    // may be the case that clazz was loaded by the Extentsion class    // loader which the parent of the system class loader. Hence the    // code below.    LogLog.debug("Trying to find ["+resource+  		   "] using ClassLoader.getSystemResource().");    return ClassLoader.getSystemResource(resource);  }     /**     Are we running under JDK 1.x?          */  public  static  boolean isJava1() {    return java1;  }    /**    * Get the Thread Context Loader which is a JDK 1.2 feature. If we    * are running under JDK 1.1 or anything else goes wrong the method    * returns <code>null<code>.    *    *  */  private static ClassLoader getTCL() throws IllegalAccessException,     InvocationTargetException {    // Are we running on a JDK 1.2 or later system?    Method method = null;    try {      method = Thread.class.getMethod("getContextClassLoader", null);    } catch (NoSuchMethodException e) {      // We are running on JDK 1.1      return null;    }        return (ClassLoader) method.invoke(Thread.currentThread(), null);  }    /**   * If running under JDK 1.2 load the specified class using the   *  <code>Thread</code> <code>contextClassLoader</code> if that   *  fails try Class.forname. Under JDK 1.1 only Class.forName is   *  used.   *   */  static public Class loadClass (String clazz) throws ClassNotFoundException {    // Just call Class.forName(clazz) if we are running under JDK 1.1    // or if we are instructed to ignore the TCL.    if(java1 || ignoreTCL) {      return Class.forName(clazz);    } else {      try {	return getTCL().loadClass(clazz);      } catch(Throwable e) {	// we reached here because tcl was null or because of a	// security exception, or because clazz could not be loaded...	// In any case we now try one more time	return Class.forName(clazz);      }    }  } }