blob: 419dc3e5df1dafd45afd22aab76adb3aa1166a5b [file] [log] [blame]
/**
* 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.aries.spifly;
import java.io.IOException;
import java.io.InputStream;
import java.net.URL;
import java.util.ArrayList;
import java.util.Collections;
import java.util.Enumeration;
import java.util.List;
/** A classloader that delegates to a number of other classloaders.
* This classloader can be used if a single classloader is needed that has
* vibisility of a number of other classloaders. For example if a Thread Context
* Classloader is needed that has visibility of a number of bundles so that
* ServiceLoader.load() can find all the services provided by these bundles.
*/
public class MultiDelegationClassloader extends ClassLoader {
private final ClassLoader[] delegates;
public MultiDelegationClassloader(ClassLoader ... classLoaders) {
if (classLoaders == null)
throw new NullPointerException();
delegates = classLoaders.clone();
}
@Override
public URL getResource(String name) {
for (ClassLoader cl : delegates) {
URL res = cl.getResource(name);
if (res != null)
return res;
}
return null;
}
@Override
public InputStream getResourceAsStream(String name) {
for (ClassLoader cl : delegates) {
InputStream is = cl.getResourceAsStream(name);
if (is != null)
return is;
}
return null;
}
@Override
public Enumeration<URL> getResources(String name) throws IOException {
List<URL> urls = new ArrayList<URL>();
for (ClassLoader cl : delegates) {
urls.addAll(Collections.list(cl.getResources(name)));
}
return Collections.enumeration(urls);
}
@Override
public Class<?> loadClass(String name) throws ClassNotFoundException {
ClassNotFoundException lastEx = null;
for (ClassLoader cl : delegates) {
try {
return cl.loadClass(name);
} catch (ClassNotFoundException e) {
lastEx = e;
}
}
throw lastEx;
}
}