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.List;
020
021 import org.apache.camel.Exchange;
022 import org.apache.camel.Processor;
023 import org.apache.camel.impl.ServiceSupport;
024 import org.apache.camel.util.ExchangeHelper;
025 import org.apache.camel.util.ServiceHelper;
026 import org.apache.commons.logging.Log;
027 import org.apache.commons.logging.LogFactory;
028
029 /**
030 * Implements try/catch/finally type processing
031 *
032 * @version $Revision: 752532 $
033 */
034 public class TryProcessor extends ServiceSupport implements Processor {
035 private static final transient Log LOG = LogFactory.getLog(TryProcessor.class);
036
037 private final Processor tryProcessor;
038 private final List<CatchProcessor> catchClauses;
039 private final Processor finallyProcessor;
040
041 public TryProcessor(Processor tryProcessor, List<CatchProcessor> catchClauses, Processor finallyProcessor) {
042 this.tryProcessor = tryProcessor;
043 this.catchClauses = catchClauses;
044 this.finallyProcessor = finallyProcessor;
045 }
046
047 public String toString() {
048 String finallyText = (finallyProcessor == null) ? "" : " Finally {" + finallyProcessor + "}";
049 return "Try {" + tryProcessor + "} " + catchClauses + finallyText;
050 }
051
052 public void process(Exchange exchange) throws Exception {
053 Exception e;
054
055 // try processor first
056 try {
057 tryProcessor.process(exchange);
058 e = exchange.getException();
059
060 // Ignore it if it was handled by the dead letter channel.
061 if (e != null && ExchangeHelper.isFailureHandled(exchange)) {
062 e = null;
063 }
064 } catch (Exception ex) {
065 e = ex;
066 exchange.setException(e);
067 }
068
069 // handle any exception occured during the try processor
070 try {
071 if (e != null) {
072 if (LOG.isDebugEnabled()) {
073 LOG.debug("Caught exception while processing exchange.", e);
074 }
075 handleException(exchange, e);
076 }
077 } finally {
078 // and run finally
079 // notice its always executed since we always enter the try block
080 processFinally(exchange);
081 }
082 }
083
084 protected void doStart() throws Exception {
085 ServiceHelper.startServices(tryProcessor, catchClauses, finallyProcessor);
086 }
087
088 protected void doStop() throws Exception {
089 ServiceHelper.stopServices(tryProcessor, catchClauses, finallyProcessor);
090 }
091
092 protected void handleException(Exchange exchange, Throwable e) throws Exception {
093 for (CatchProcessor catchClause : catchClauses) {
094 if (catchClause.catches(e)) {
095 // lets attach the exception to the exchange
096 Exchange localExchange = exchange.copy();
097
098 localExchange.setProperty(Exchange.EXCEPTION_CAUGHT, e);
099 // give the rest of the pipeline another chance
100 localExchange.setException(null);
101
102 // do not catch any exception here, let it propagate up
103 catchClause.process(localExchange);
104 localExchange.removeProperty(Exchange.EXCEPTION_CAUGHT);
105 ExchangeHelper.copyResults(exchange, localExchange);
106 return;
107 }
108 }
109 }
110
111 protected void processFinally(Exchange exchange) throws Exception {
112 if (finallyProcessor != null) {
113 Exception lastException = exchange.getException();
114 exchange.setException(null);
115
116 // do not catch any exception here, let it propagate up
117 finallyProcessor.process(exchange);
118 if (exchange.getException() == null) {
119 exchange.setException(lastException);
120 }
121 }
122 }
123 }