/*
* Copyright 2001-2004 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.axis.utils;
import java.io.InputStream;
import java.io.File;
import java.net.MalformedURLException;
import java.net.URL;
import java.net.URLClassLoader;
import java.security.AccessController;
import java.security.PrivilegedAction;
/**
* Utility methods for Class Loading.
*
* @author Davanum Srinvas (dims@yahoo.com)
* @author Matthew Pocock (matthew_pocock@yahoo.co.uk)
*/
public final class ClassUtils {
/** default class loader */
private static ClassLoader defaultClassLoader
= ClassUtils.class.getClassLoader();
/** hash table of class loaders */
private static java.util.Hashtable classloaders = new java.util.Hashtable();
/**
* Set the default ClassLoader. If loader is null, the default loader is
* not changed.
*
* @param loader the new default ClassLoader
*/
public static void setDefaultClassLoader(ClassLoader loader) {
if (loader != null)
defaultClassLoader = loader;
}
public static ClassLoader getDefaultClassLoader() {
return defaultClassLoader;
}
/**
* Set the ClassLoader associated with the given className. If either the
* class name or the loader are null, no action is performed.
*
* @param className the name of a class
* @param loader the ClassLoader for the class
*/
public static void setClassLoader(String className, ClassLoader loader) {
if (className != null && loader != null)
classloaders.put(className, loader);
}
/**
* Obtain the ClassLoader (if any) associated with the given
* className.
*
* @param className the name of a class
* @return class loader
*/
public static ClassLoader getClassLoader(String className) {
if (className == null) {
return null;
}
return (ClassLoader) classloaders.get(className);
}
/**
* Deregister the ClassLoader for a given className.
*
* @param className the name of a class
*/
public static void removeClassLoader(String className) {
classloaders.remove(className);
}
/**
* Use this method instead of Class.forName
*
* @param className Class name
* @return java class
* @throws ClassNotFoundException if the class is not found
*/
public static Class forName(String className)
throws ClassNotFoundException {
return loadClass(className);
}
/**
* Use this method instead of Class.forName (String className, boolean init, ClassLoader loader)
*
* @param _className Class name
* @param init initialize the class
* @param _loader class loader
* @return java class
*
* @throws ClassNotFoundException if the class is not found
*/
public static Class forName(
String _className, boolean init, ClassLoader _loader)
throws ClassNotFoundException {
// Create final vars for doPrivileged block
final String className = _className;
final ClassLoader loader = _loader;
try {
// Get the class within a doPrivleged block
Object ret =
AccessController.doPrivileged(
new PrivilegedAction() {
public Object run() {
try {
return Class.forName(className, true, loader);
} catch (Throwable e) {
return e;
}
}
});
// If the class was located, return it. Otherwise throw exception
if (ret instanceof Class) {
return (Class) ret;
} else if (ret instanceof ClassNotFoundException) {
throw (ClassNotFoundException) ret;
} else {
throw new ClassNotFoundException(_className);
}
} catch (ClassNotFoundException cnfe) {
return loadClass(className);
}
}
/**
* Loads the class from the context class loader and then falls back to
* getDefaultClassLoader().forName
*
* @param _className Class name
* @return java class
* @throws ClassNotFoundException if the class is not found
*/
private static Class loadClass(String _className)
throws ClassNotFoundException {
// Create final vars for doPrivileged block
final String className = _className;
// Get the class within a doPrivleged block
Object ret =
AccessController.doPrivileged(
new PrivilegedAction() {
public Object run() {
try {
// Check if the class is a registered class then
// use the classloader for that class.
ClassLoader classLoader = getClassLoader(className);
return Class.forName(className, true, classLoader);
} catch (ClassNotFoundException cnfe) {
} catch (SecurityException cnfe) {
}
try {
// Try the context class loader
ClassLoader classLoader =
Thread.currentThread().getContextClassLoader();
return Class.forName(className, true, classLoader);
} catch (ClassNotFoundException cnfe2) {
try {
// Try the classloader that loaded this class.
ClassLoader classLoader =
ClassUtils.class.getClassLoader();
return Class.forName(className, true, classLoader);
} catch (ClassNotFoundException cnfe3) {
// Try the default class loader.
try {
return defaultClassLoader.loadClass(
className);
} catch (Throwable e) {
// Still not found, return exception
return e;
}
}
}
}
});
// If the class was located, return it. Otherwise throw exception
if (ret instanceof Class) {
return (Class) ret;
} else if (ret instanceof ClassNotFoundException) {
throw (ClassNotFoundException) ret;
} else {
throw new ClassNotFoundException(_className);
}
}
/**
* Get an input stream from a named resource.
* Tries
* <ol>
* <li>the classloader that loaded "clazz" first,
* <li>the system classloader
* <li>the class "clazz" itself
* </ol>
* @param clazz class to use in the lookups
* @param resource resource string to look for
* @param checkThreadContextFirst check the thread context first?
* @return input stream if found, or null
*/
public static InputStream getResourceAsStream(Class clazz, String resource, boolean checkThreadContextFirst) {
InputStream myInputStream = null;
if (checkThreadContextFirst &&
Thread.currentThread().getContextClassLoader() != null) {
// try the context class loader.
myInputStream =
Thread.currentThread().getContextClassLoader()
.getResourceAsStream(resource);
}
if (myInputStream == null) {
// if not found in context class loader fall back to default
myInputStream = getResourceAsStream(clazz, resource);
}
return myInputStream;
}
/**
* Get an input stream from a named resource.
* Tries
* <ol>
* <li>the classloader that loaded "clazz" first,
* <li>the system classloader
* <li>the class "clazz" itself
* </ol>
* @param clazz class to use in the lookups
* @param resource resource string to look for
* @return input stream if found, or null
*/
public static InputStream getResourceAsStream(Class clazz, String resource) {
InputStream myInputStream = null;
if(clazz.getClassLoader()!=null) {
// Try the class loader that loaded this class.
myInputStream = clazz.getClassLoader().getResourceAsStream(resource);
} else {
// Try the system class loader.
myInputStream = ClassLoader.getSystemClassLoader().getResourceAsStream(resource);
}
if (myInputStream == null && Thread.currentThread().getContextClassLoader() != null) {
// try the context class loader.
myInputStream = Thread.currentThread().getContextClassLoader().getResourceAsStream(resource);
}
if (myInputStream == null) {
// if not found in classpath fall back to default
myInputStream = clazz.getResourceAsStream(resource);
}
return myInputStream;
}
/**
* Creates a new ClassLoader from a classpath specification and a parent
* class loader.
* The classpath string will be split using the system path seperator
* character (e.g. : or ;), just as the java system-wide class path is
* processed.
*
* @param classpath the classpath String
* @param parent the parent ClassLoader, or null if the default is to be
* used
* @throws SecurityException if you don't have privilages to create
* class loaders
* @throws IllegalArgumentException if your classpath string is silly
*/
public static ClassLoader createClassLoader(String classpath,
ClassLoader parent)
throws SecurityException
{
String[] names = StringUtils.split(classpath, System.getProperty("path.separator").charAt(0));
URL[] urls = new URL[names.length];
try {
for(int i = 0; i < urls.length; i++)
urls[i] = new File(names[i]).toURL();
}
catch (MalformedURLException e) {
// I don't think this is possible, so I'm throwing this as an
// un-checked exception
throw (IllegalArgumentException) new IllegalArgumentException(
"Unable to parse classpath: " + classpath);
}
return new URLClassLoader(urls, parent);
}
}
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