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From wer...@apache.org
Subject svn commit: r355717 - /webservices/commons/trunk/policy/src/org/apache/ws/policy/util/Loader.java
Date Sat, 10 Dec 2005 08:31:35 GMT
Author: werner
Date: Sat Dec 10 00:31:29 2005
New Revision: 355717

URL: http://svn.apache.org/viewcvs?rev=355717&view=rev
Log:
Chckin the Loader.

Added:
    webservices/commons/trunk/policy/src/org/apache/ws/policy/util/Loader.java

Added: webservices/commons/trunk/policy/src/org/apache/ws/policy/util/Loader.java
URL: http://svn.apache.org/viewcvs/webservices/commons/trunk/policy/src/org/apache/ws/policy/util/Loader.java?rev=355717&view=auto
==============================================================================
--- webservices/commons/trunk/policy/src/org/apache/ws/policy/util/Loader.java (added)
+++ webservices/commons/trunk/policy/src/org/apache/ws/policy/util/Loader.java Sat Dec 10
00:31:29 2005
@@ -0,0 +1,164 @@
+/*
+ * Copyright  2003-2004 The Apache Software Foundation.
+ *
+ *  Licensed 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.ws.policy.util;
+
+import org.apache.commons.logging.Log;
+import org.apache.commons.logging.LogFactory;
+
+import java.lang.reflect.InvocationTargetException;
+import java.net.URL;
+
+/**
+ * Load resources (or images) from various sources.
+ * <p/>
+ *
+ * @author Davanum Srinivas (dims@yahoo.com).
+ */
+public class Loader {
+    private static Log log = LogFactory.getLog(Loader.class.getName());
+
+    /**
+     * This method will search for <code>resource</code> in different
+     * places. The rearch 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>).
+     * <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>
+     * <p/>
+     *
+     * @param resource
+     * @return TODO
+     */
+    static public URL getResource(String resource) {
+        ClassLoader classLoader = null;
+        URL url = null;
+        try {
+            // We could not find resource. Ler us now try with the
+            // classloader that loaded this class.
+            classLoader = getTCL();
+            if (classLoader != null) {
+                log.debug("Trying to find [" + resource + "] using " + classLoader + " class
loader.");
+                url = classLoader.getResource(resource);
+                if (url != null) {
+                    return url;
+                }
+            }
+        } catch (Throwable t) {
+            log.warn("Caught Exception while in Loader.getResource. This may be innocuous.",
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.
+        log.debug("Trying to find [" + resource + "] using ClassLoader.getSystemResource().");
+        return ClassLoader.getSystemResource(resource);
+    }
+    
+
+    /**
+     * Try to get the resource with the specified class loader
+     * <p/>
+     *
+     * @param cl
+     * @param clazz
+     * @return Class
+     * @throws ClassNotFoundException
+     */
+    static public URL getResource(ClassLoader loader, String resource) throws ClassNotFoundException
{
+        URL url = null;
+        try {
+            if (loader != null) {
+                log.debug("Trying to find [" + resource + "] using " + loader + " class loader.");
+                url = loader.getResource(resource);
+                if (url != null) {
+                    return url;
+                }
+            }
+        } catch (Throwable t) {
+            log.warn("Caught Exception while in Loader.getResource. This may be innocuous.",
t);
+        }
+        return getResource(resource);
+    }
+
+    /**
+     * Get the Thread context class loader.
+     * <p/>
+     *
+     * @return
+     * @throws IllegalAccessException
+     * @throws InvocationTargetException
+     */
+    static public ClassLoader getTCL() throws IllegalAccessException, InvocationTargetException
{
+        return Thread.currentThread().getContextClassLoader();
+    }
+
+    /**
+     * Try the specified classloader and then fall back to the loadClass
+     * <p/>
+     *
+     * @param cl
+     * @param clazz
+     * @return Class
+     * @throws ClassNotFoundException
+     */
+    static public Class loadClass(ClassLoader loader, String clazz) throws ClassNotFoundException
{
+        try {
+            if(loader != null) {
+                Class c = loader.loadClass(clazz);
+                if (c != null)
+                    return c;
+            }
+        } catch (Throwable e) {
+        }
+        return loadClass(clazz);
+    }
+
+    /**
+     * If running under JDK 1.2 load the specified class using the
+     * <code>Thread</code> <code>contextClassLoader</code> if that
+     * fails try Class.forname.
+     * <p/>
+     *
+     * @param clazz
+     * @return TODO
+     * @throws ClassNotFoundException
+     */
+    static public Class loadClass(String clazz) throws ClassNotFoundException {
+        try {
+            ClassLoader tcl = getTCL();	
+            
+            if(tcl != null) {
+                Class c = tcl.loadClass(clazz);
+                if (c != null)
+                    return c;
+            }
+        } 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);
+    }
+}



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