001 /*
002 * Licensed to the Apache Software Foundation (ASF) under one or more
003 * contributor license agreements. See the NOTICE file distributed with
004 * this work for additional information regarding copyright ownership.
005 * The ASF licenses this file to You under the Apache License, Version 2.0
006 * (the "License"); you may not use this file except in compliance with
007 * the License. You may obtain a copy of the License at
008 *
009 * http://www.apache.org/licenses/LICENSE-2.0
010 *
011 * Unless required by applicable law or agreed to in writing, software
012 * distributed under the License is distributed on an "AS IS" BASIS,
013 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
014 * See the License for the specific language governing permissions and
015 * limitations under the License.
016 */
017 package org.apache.commons.jci.stores;
018
019 import org.apache.commons.jci.utils.ConversionUtils;
020 import org.apache.commons.logging.Log;
021 import org.apache.commons.logging.LogFactory;
022
023
024 /**
025 * A ClassLoader backed by an array of ResourceStores
026 *
027 * @author tcurdt
028 */
029 public final class ResourceStoreClassLoader extends ClassLoader {
030
031 private final Log log = LogFactory.getLog(ResourceStoreClassLoader.class);
032
033 private final ResourceStore[] stores;
034
035 public ResourceStoreClassLoader( final ClassLoader pParent, final ResourceStore[] pStores ) {
036 super(pParent);
037
038 stores = new ResourceStore[pStores.length];
039 System.arraycopy(pStores, 0, stores, 0, stores.length);
040 }
041
042 private Class<?> fastFindClass(final String name) {
043
044 if (stores != null) {
045 for (ResourceStore store : stores) {
046 final byte[] clazzBytes = store.read(ConversionUtils.convertClassToResourcePath(name));
047 if (clazzBytes != null) {
048 log.debug(getId() + " found class: " + name + " (" + clazzBytes.length + " bytes)");
049 return defineClass(name, clazzBytes, 0, clazzBytes.length);
050 }
051 }
052 }
053
054 return null;
055 }
056
057 @Override
058 protected synchronized Class<?> loadClass(String name, boolean resolve) throws ClassNotFoundException {
059 // log.debug(getId() + " looking for: " + name);
060 Class<?> clazz = findLoadedClass(name);
061
062 if (clazz == null) {
063 clazz = fastFindClass(name);
064
065 if (clazz == null) {
066
067 final ClassLoader parent = getParent();
068 if (parent != null) {
069 clazz = parent.loadClass(name);
070 // log.debug(getId() + " delegating loading to parent: " + name);
071 } else {
072 throw new ClassNotFoundException(name);
073 }
074
075 } else {
076 log.debug(getId() + " loaded from store: " + name);
077 }
078 }
079
080 if (resolve) {
081 resolveClass(clazz);
082 }
083
084 return clazz;
085 }
086
087 @Override
088 protected Class<?> findClass( final String name ) throws ClassNotFoundException {
089 final Class<?> clazz = fastFindClass(name);
090 if (clazz == null) {
091 throw new ClassNotFoundException(name);
092 }
093 return clazz;
094 }
095
096 private String getId() {
097 return "" + this + "[" + this.getClass().getClassLoader() + "]";
098 }
099 }