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The Apache WSS4J project provides a Java implementation of the primary security standards
for Web Services, namely the OASIS Web Services Security (WS-Security) specifications
from the OASIS Web Services Security TC.
/*
* 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.security.util;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import java.lang.reflect.InvocationTargetException;
import java.net.URL;
import java.security.AccessController;
import java.security.PrivilegedAction;
/**
* Load resources (or images) from various sources.
*
*
* @author Davanum Srinivas ([email protected]).
*/
public class Loader {
private static Log log = LogFactory.getLog(Loader.class.getName());
/**
* This method will search for resource in different
* places. The search order is as follows:
*
* - Search for
resource using the thread context
* class loader under Java2.
* - Try one last time with
*
ClassLoader.getSystemResource(resource), that is is
* using the system class loader in JDK 1.2 and virtual machine's
* built-in class loader in JDK 1.1.
*
*
*
* @param resource
* @return TODO
*/
public static URL getResource(String resource) {
ClassLoader classLoader = null;
URL url = null;
try {
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 Extension 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);
}
/**
* This method will search for resource in different
* places. The search order is as follows:
*
* - Search for
resource using the supplied class loader.
* If that fails, search for resource using the thread context
* class loader.
* - Try one last time with
*
ClassLoader.getSystemResource(resource), that is is
* using the system class loader in JDK 1.2 and virtual machine's
* built-in class loader in JDK 1.1.
*
*
*
* @param resource
* @return TODO
*/
public static URL getResource(ClassLoader loader, String resource) {
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.
*
*
* @return the Thread context class loader
* @throws IllegalAccessException
* @throws InvocationTargetException
*/
public static ClassLoader getTCL() throws IllegalAccessException, InvocationTargetException {
return (ClassLoader)AccessController.doPrivileged(new PrivilegedAction() {
public Object run() {
return Thread.currentThread().getContextClassLoader();
}
});
}
/**
* Get the class loader of the class argument
*
*
* @return the class loader of the argument
*/
public static ClassLoader getClassLoader(final Class clazz) {
return (ClassLoader)AccessController.doPrivileged(new PrivilegedAction() {
public Object run() {
return clazz.getClassLoader();
}
});
}
/**
* Try the specified classloader and then fall back to the loadClass
*
*
* @param loader
* @param clazz
* @return Class
* @throws ClassNotFoundException
*/
public static 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) {
log.warn(e.getMessage(), e);
}
return loadClass(clazz, true);
}
/**
* If running under JDK 1.2 load the specified class using the
* Thread contextClassLoader if that
* fails try Class.forname.
*
*
* @param clazz
* @return TODO
* @throws ClassNotFoundException
*/
public static Class loadClass(String clazz) throws ClassNotFoundException {
return loadClass(clazz, true);
}
public static Class loadClass(String clazz, boolean warn) throws ClassNotFoundException {
try {
ClassLoader tcl = getTCL();
if (tcl != null) {
Class c = tcl.loadClass(clazz);
if (c != null) {
return c;
}
}
} catch (Throwable e) {
if (warn) {
log.warn(e.getMessage(), e);
} else {
log.debug(e.getMessage(), 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);
}
}