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.geronimo.transformer;
018    
019    import java.lang.instrument.ClassFileTransformer;
020    import java.lang.instrument.IllegalClassFormatException;
021    import java.security.ProtectionDomain;
022    import java.util.List;
023    import java.util.ArrayList;
024    import java.util.Iterator;
025    
026    /**
027     * @version $Rev: 706640 $ $Date: 2008-10-21 14:44:05 +0000 (Tue, 21 Oct 2008) $
028     */
029    public class TransformerCollection implements ClassFileTransformer {
030    
031        private final List<ClassFileTransformer> transformers = new ArrayList<ClassFileTransformer>();
032    
033        // hack to force load of ArrayList$Itr class. This avoids a potential Classloader deadlock during startup
034        // see GERONIMO-3687
035        {
036            for (ClassFileTransformer transformer : transformers) {
037            }
038        }
039    
040        public byte[] transform(ClassLoader loader, String className, Class<?> classBeingRedefined, ProtectionDomain protectionDomain, byte[] classfileBuffer) throws IllegalClassFormatException {
041            boolean changed = false;
042            for (ClassFileTransformer transformer : transformers) {
043                byte[] transformed = transformer.transform(loader, className, classBeingRedefined, protectionDomain, classfileBuffer);
044                if (transformed != null) {
045                    changed = true;
046                    classfileBuffer = transformed;
047                }
048            }
049            return changed? classfileBuffer: null;
050        }
051    
052        public void addTransformer(ClassFileTransformer classFileTransformer) {
053            transformers.add(classFileTransformer);
054        }
055    
056        public void removeTransformer(ClassFileTransformer classFileTransformer) {
057            transformers.remove(classFileTransformer);
058        }
059    }