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: 794544 $ 035 */ 036 public class TryProcessor extends ServiceSupport implements Processor, Navigate<Processor>, Traceable { 037 private static final transient Log LOG = LogFactory.getLog(TryProcessor.class); 038 039 protected final Processor tryProcessor; 040 protected final List<CatchProcessor> catchClauses; 041 protected 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 != null ? catchClauses : "") + finallyText; 052 } 053 054 public String getTraceLabel() { 055 return "Try"; 056 } 057 058 public void process(Exchange exchange) throws Exception { 059 Exception e; 060 061 // try processor first 062 try { 063 tryProcessor.process(exchange); 064 e = exchange.getException(); 065 066 // Ignore it if it was handled by the dead letter channel. 067 if (e != null && ExchangeHelper.isFailureHandled(exchange)) { 068 e = null; 069 } 070 } catch (Exception ex) { 071 e = ex; 072 exchange.setException(e); 073 } 074 075 // handle any exception occured during the try processor 076 try { 077 if (e != null) { 078 handleException(exchange, e); 079 } 080 } finally { 081 // and run finally 082 // notice its always executed since we always enter the try block 083 processFinally(exchange); 084 } 085 } 086 087 protected void doStart() throws Exception { 088 ServiceHelper.startServices(tryProcessor, catchClauses, finallyProcessor); 089 } 090 091 protected void doStop() throws Exception { 092 ServiceHelper.stopServices(finallyProcessor, catchClauses, tryProcessor); 093 } 094 095 protected void handleException(Exchange exchange, Throwable e) throws Exception { 096 if (catchClauses == null) { 097 return; 098 } 099 100 for (CatchProcessor catchClause : catchClauses) { 101 if (catchClause.catches(exchange, e)) { 102 if (LOG.isTraceEnabled()) { 103 LOG.trace("This TryProcessor catches the exception: " + e.getClass().getName() + " caused by: " + e.getMessage()); 104 } 105 106 // lets attach the exception to the exchange 107 Exchange localExchange = exchange.copy(); 108 109 localExchange.setProperty(Exchange.EXCEPTION_CAUGHT, e); 110 // give the rest of the pipeline another chance 111 localExchange.setException(null); 112 113 // do not catch any exception here, let it propagate up 114 catchClause.process(localExchange); 115 116 boolean handled = catchClause.handles(exchange); 117 118 if (LOG.isDebugEnabled()) { 119 LOG.debug("The exception is handled: " + handled + " for the exception: " + e.getClass().getName() 120 + " caused by: " + e.getMessage()); 121 } 122 123 if (handled) { 124 localExchange.removeProperty(Exchange.EXCEPTION_CAUGHT); 125 } else { 126 // put exception back as it was not handled 127 if (localExchange.getException() == null) { 128 localExchange.setException(localExchange.getProperty(Exchange.EXCEPTION_CAUGHT, Exception.class)); 129 } 130 } 131 132 // copy result back to the original exchange 133 ExchangeHelper.copyResults(exchange, localExchange); 134 return; 135 } 136 } 137 138 if (LOG.isTraceEnabled()) { 139 LOG.trace("This TryProcessor does not catch the exception: " + e.getClass().getName() + " caused by: " + e.getMessage()); 140 } 141 } 142 143 protected void processFinally(Exchange exchange) throws Exception { 144 if (finallyProcessor != null) { 145 Exception lastException = exchange.getException(); 146 exchange.setException(null); 147 148 // do not catch any exception here, let it propagate up 149 finallyProcessor.process(exchange); 150 if (exchange.getException() == null) { 151 exchange.setException(lastException); 152 } 153 } 154 } 155 156 public List<Processor> next() { 157 if (!hasNext()) { 158 return null; 159 } 160 List<Processor> answer = new ArrayList<Processor>(); 161 if (tryProcessor != null) { 162 answer.add(tryProcessor); 163 } 164 if (catchClauses != null) { 165 answer.addAll(catchClauses); 166 } 167 if (finallyProcessor != null) { 168 answer.add(finallyProcessor); 169 } 170 return answer; 171 } 172 173 public boolean hasNext() { 174 return tryProcessor != null; 175 } 176 }