org.apache.tuscany.sca.extensibility.impl.ClassLoaderDelegate Maven / Gradle / Ivy
/*
* 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.tuscany.sca.extensibility.impl;
import java.io.IOException;
import java.net.URL;
import java.util.ArrayList;
import java.util.Collection;
import java.util.Collections;
import java.util.Enumeration;
import java.util.HashSet;
import java.util.List;
import java.util.Set;
/**
* A classloader that can delegate to a list of other classloaders
*/
public class ClassLoaderDelegate extends ClassLoader {
private final List classLoaders = new ArrayList();
/**
* @param parent The parent classloaders
* @param loaders A list of classloaders to be used to load classes or resources
*/
public ClassLoaderDelegate(ClassLoader parent, Collection loaders) {
super(parent);
if (loaders != null) {
for (ClassLoader cl : loaders) {
if (cl != null && cl != parent && !classLoaders.contains(cl)) {
this.classLoaders.add(cl);
}
}
}
}
@Override
protected Class findClass(String className) throws ClassNotFoundException {
for (ClassLoader delegate : classLoaders) {
try {
return delegate.loadClass(className);
} catch (ClassNotFoundException e) {
continue;
}
}
throw new ClassNotFoundException(className);
}
@Override
protected URL findResource(String resName) {
for (ClassLoader delegate : classLoaders) {
URL url = delegate.getResource(resName);
if (url != null) {
return url;
}
}
return null;
}
@Override
protected Enumeration findResources(String resName) throws IOException {
Set urlSet = new HashSet();
for (ClassLoader delegate : classLoaders) {
Enumeration urls = delegate.getResources(resName);
if (urls != null) {
while (urls.hasMoreElements()) {
urlSet.add(urls.nextElement());
}
}
}
return Collections.enumeration(urlSet);
}
}