    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    }