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 java.util.ArrayList;
020 import java.util.List;
021
022 import org.apache.camel.Exchange;
023 import org.apache.camel.Navigate;
024 import org.apache.camel.Processor;
025 import org.apache.camel.impl.ServiceSupport;
026 import org.apache.camel.util.ServiceHelper;
027
028 /**
029 * A Delegate pattern which delegates processing to a nested processor which can
030 * be useful for implementation inheritance when writing an {@link org.apache.camel.spi.Policy}
031 *
032 * @version $Revision: 769303 $
033 */
034 public class DelegateProcessor extends ServiceSupport implements Processor, Navigate {
035 protected Processor processor;
036
037 public DelegateProcessor() {
038 }
039
040 public DelegateProcessor(Processor processor) {
041 if (processor == this) {
042 throw new IllegalArgumentException("Recursive DelegateProcessor!");
043 }
044 this.processor = processor;
045 }
046
047 public void process(Exchange exchange) throws Exception {
048 processNext(exchange);
049 }
050
051 protected void processNext(Exchange exchange) throws Exception {
052 if (processor != null) {
053 processor.process(exchange);
054 }
055 }
056
057 @Override
058 public String toString() {
059 return "Delegate[" + processor + "]";
060 }
061
062 public Processor getProcessor() {
063 return processor;
064 }
065
066 public void setProcessor(Processor processor) {
067 this.processor = processor;
068 }
069
070 protected void doStart() throws Exception {
071 ServiceHelper.startServices(processor);
072 }
073
074 protected void doStop() throws Exception {
075 ServiceHelper.stopServices(processor);
076 }
077
078 /**
079 * Proceed with the underlying delegated processor
080 */
081 public void proceed(Exchange exchange) throws Exception {
082 processNext(exchange);
083 }
084
085 public boolean hasNext() {
086 return processor != null;
087 }
088
089 public List<Processor> next() {
090 if (!hasNext()) {
091 return null;
092 }
093 List<Processor> answer = new ArrayList<Processor>(1);
094 answer.add(processor);
095 return answer;
096 }
097
098 }