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.ExchangeHelper; 027 import org.apache.camel.util.ServiceHelper; 028 import org.apache.commons.logging.Log; 029 import org.apache.commons.logging.LogFactory; 030 031 /** 032 * Implements try/catch/finally type processing 033 * 034 * @version $Revision: 769303 $ 035 */ 036 public class TryProcessor extends ServiceSupport implements Processor, Navigate<Processor> { 037 private static final transient Log LOG = LogFactory.getLog(TryProcessor.class); 038 039 private final Processor tryProcessor; 040 private final List<CatchProcessor> catchClauses; 041 private final Processor finallyProcessor; 042 043 public TryProcessor(Processor tryProcessor, List<CatchProcessor> catchClauses, Processor finallyProcessor) { 044 this.tryProcessor = tryProcessor; 045 this.catchClauses = catchClauses; 046 this.finallyProcessor = finallyProcessor; 047 } 048 049 public String toString() { 050 String finallyText = (finallyProcessor == null) ? "" : " Finally {" + finallyProcessor + "}"; 051 return "Try {" + tryProcessor + "} " + catchClauses + finallyText; 052 } 053 054 public void process(Exchange exchange) throws Exception { 055 Exception e; 056 057 // try processor first 058 try { 059 tryProcessor.process(exchange); 060 e = exchange.getException(); 061 062 // Ignore it if it was handled by the dead letter channel. 063 if (e != null && ExchangeHelper.isFailureHandled(exchange)) { 064 e = null; 065 } 066 } catch (Exception ex) { 067 e = ex; 068 exchange.setException(e); 069 } 070 071 // handle any exception occured during the try processor 072 try { 073 if (e != null) { 074 handleException(exchange, e); 075 } 076 } finally { 077 // and run finally 078 // notice its always executed since we always enter the try block 079 processFinally(exchange); 080 } 081 } 082 083 protected void doStart() throws Exception { 084 ServiceHelper.startServices(tryProcessor, catchClauses, finallyProcessor); 085 } 086 087 protected void doStop() throws Exception { 088 ServiceHelper.stopServices(finallyProcessor, catchClauses, tryProcessor); 089 } 090 091 protected void handleException(Exchange exchange, Throwable e) throws Exception { 092 for (CatchProcessor catchClause : catchClauses) { 093 if (catchClause.catches(exchange, e)) { 094 if (LOG.isTraceEnabled()) { 095 LOG.trace("This TryProcessor catches the exception: " + e.getClass().getName() + " caused by: " + e.getMessage()); 096 } 097 098 // lets attach the exception to the exchange 099 Exchange localExchange = exchange.copy(); 100 101 localExchange.setProperty(Exchange.EXCEPTION_CAUGHT, e); 102 // give the rest of the pipeline another chance 103 localExchange.setException(null); 104 105 // do not catch any exception here, let it propagate up 106 catchClause.process(localExchange); 107 108 boolean handled = catchClause.handles(exchange); 109 110 if (LOG.isDebugEnabled()) { 111 LOG.debug("The exception is handled: " + handled + " for the exception: " + e.getClass().getName() 112 + " caused by: " + e.getMessage()); 113 } 114 115 if (handled) { 116 localExchange.removeProperty(Exchange.EXCEPTION_CAUGHT); 117 } else { 118 // put exception back as it was not handled 119 if (localExchange.getException() == null) { 120 localExchange.setException(localExchange.getProperty(Exchange.EXCEPTION_CAUGHT, Exception.class)); 121 } 122 } 123 124 // copy result back to the original exchange 125 ExchangeHelper.copyResults(exchange, localExchange); 126 return; 127 } 128 } 129 130 if (LOG.isTraceEnabled()) { 131 LOG.trace("This TryProcessor does not catch the exception: " + e.getClass().getName() + " caused by: " + e.getMessage()); 132 } 133 } 134 135 protected void processFinally(Exchange exchange) throws Exception { 136 if (finallyProcessor != null) { 137 Exception lastException = exchange.getException(); 138 exchange.setException(null); 139 140 // do not catch any exception here, let it propagate up 141 finallyProcessor.process(exchange); 142 if (exchange.getException() == null) { 143 exchange.setException(lastException); 144 } 145 } 146 } 147 148 public List<Processor> next() { 149 if (!hasNext()) { 150 return null; 151 } 152 List<Processor> answer = new ArrayList<Processor>(); 153 if (tryProcessor != null) { 154 answer.add(tryProcessor); 155 } 156 if (catchClauses != null) { 157 answer.addAll(catchClauses); 158 } 159 if (finallyProcessor != null) { 160 answer.add(finallyProcessor); 161 } 162 return answer; 163 } 164 165 public boolean hasNext() { 166 return tryProcessor != null; 167 } 168 }