| /* |
| * 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.karaf.cellar.core.utils; |
| |
| import org.osgi.framework.Bundle; |
| |
| import java.net.URL; |
| import java.util.Map; |
| import java.util.concurrent.ConcurrentHashMap; |
| import java.util.concurrent.ConcurrentMap; |
| |
| /** |
| * A class loader which combines multiple bundle class loaders. |
| * A bundle can add itself for to this class loader, so that the class loader can load classes from the bundle. |
| * It is meant to be used together with the extender pattern in order to extends Cellar class space. |
| */ |
| public class CombinedClassLoader extends ClassLoader { |
| |
| private final ConcurrentMap<Long, Bundle> bundles = new ConcurrentHashMap<Long, Bundle>(); |
| |
| private final ConcurrentMap<String, Bundle> classBundleCache = new ConcurrentHashMap<String, Bundle>(); |
| |
| public void init() { |
| bundles.clear(); |
| classBundleCache.clear(); |
| } |
| |
| public void destroy() { |
| bundles.clear(); |
| classBundleCache.clear(); |
| } |
| |
| public void addBundle(Bundle bundle) { |
| bundles.put(bundle.getBundleId(), bundle); |
| } |
| |
| public void removeBundle(Bundle bundle) { |
| bundles.remove(bundle.getBundleId()); |
| // Remove all bundle classes from class name to bundle cache |
| for (Map.Entry<String, Bundle> entry : classBundleCache.entrySet()) { |
| if (entry.getValue().getBundleId() == bundle.getBundleId()) { |
| classBundleCache.remove(entry.getKey()); |
| } |
| } |
| } |
| |
| @Override |
| public Class<?> findClass(String name) throws ClassNotFoundException { |
| // Trying to find class using class name to bundle cache first |
| Bundle bundle = classBundleCache.get(name); |
| if (bundle != null) { |
| Class<?> clazz = loadClassFromBundle(name, bundle); |
| if (clazz != null) { |
| return clazz; |
| } |
| // Remove stale cache entry |
| classBundleCache.remove(name); |
| } |
| // Class not found using class name to bundle cache, check all registered bundles |
| for (Map.Entry<Long, Bundle> entry : bundles.entrySet()) { |
| bundle = entry.getValue(); |
| Class<?> clazz = loadClassFromBundle(name, bundle); |
| if (clazz != null) { |
| classBundleCache.put(name, bundle); |
| return clazz; |
| } |
| } |
| throw new ClassNotFoundException(name); |
| } |
| |
| private Class<?> loadClassFromBundle(String name, Bundle bundle) { |
| try { |
| if (bundle.getState() == Bundle.ACTIVE || bundle.getState() == Bundle.STARTING) { |
| return bundle.loadClass(name); |
| } |
| } catch (ClassNotFoundException cnfe) { |
| } |
| return null; |
| } |
| |
| @Override |
| public URL getResource(String name) { |
| for (Map.Entry<Long, Bundle> entry : bundles.entrySet()) { |
| Bundle bundle = entry.getValue(); |
| if (bundle.getState() == Bundle.ACTIVE || bundle.getState() == Bundle.STARTING) { |
| URL url = bundle.getResource(name); |
| if (url != null) { |
| return url; |
| } |
| } |
| } |
| return null; |
| } |
| |
| } |