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: 476049 $ $Date: 2006-11-16 23:35:17 -0500 (Thu, 16 Nov 2006) $
028     */
029    public class TransformerCollection implements ClassFileTransformer {
030    
031        private final List<ClassFileTransformer> transformers = new ArrayList<ClassFileTransformer>();
032    
033        public byte[] transform(ClassLoader loader, String className, Class<?> classBeingRedefined, ProtectionDomain protectionDomain, byte[] classfileBuffer) throws IllegalClassFormatException {
034            boolean changed = false;
035            for (ClassFileTransformer transformer : transformers) {
036                byte[] transformed = transformer.transform(loader, className, classBeingRedefined, protectionDomain, classfileBuffer);
037                if (transformed != null) {
038                    changed = true;
039                    classfileBuffer = transformed;
040                }
041            }
042            return changed? classfileBuffer: null;
043        }
044    
045        public void addTransformer(ClassFileTransformer classFileTransformer) {
046            transformers.add(classFileTransformer);
047        }
048    
049        public void removeTransformer(ClassFileTransformer classFileTransformer) {
050            transformers.remove(classFileTransformer);
051        }
052    }