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.camel.processor;
018    
019    import org.apache.camel.Exchange;
020    import org.apache.camel.Processor;
021    import org.apache.camel.impl.ServiceSupport;
022    import org.apache.camel.util.ServiceHelper;
023    
024    /**
025     * A Delegate pattern which delegates processing to a nested processor which can
026     * be useful for implementation inheritance when writing an {@link org.apache.camel.spi.Policy}
027     * 
028     * @version $Revision: 751221 $
029     */
030    public class DelegateProcessor extends ServiceSupport implements Processor {
031        protected Processor processor;
032    
033        public DelegateProcessor() {
034        }
035    
036        public DelegateProcessor(Processor processor) {
037            if (processor == this) {
038                throw new IllegalArgumentException("Recursive DelegateProcessor!");
039            }
040            this.processor = processor;
041        }
042    
043        public void process(Exchange exchange) throws Exception {
044            processNext(exchange);
045        }
046    
047        protected void processNext(Exchange exchange) throws Exception {
048            if (processor != null) {
049                processor.process(exchange);
050            }
051        }
052    
053        @Override
054        public String toString() {
055            return "Delegate(" + processor + ")";
056        }
057    
058        public Processor getProcessor() {
059            return processor;
060        }
061    
062        public void setProcessor(Processor processor) {
063            this.processor = processor;
064        }
065    
066        protected void doStart() throws Exception {
067            ServiceHelper.startServices(processor);
068        }
069    
070        protected void doStop() throws Exception {
071            ServiceHelper.stopServices(processor);
072        }
073    
074        /**
075         * Proceed with the underlying delegated processor
076         */
077        public void proceed(Exchange exchange) throws Exception {
078            processNext(exchange);
079        }
080    }