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 }