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.RuntimeCamelException;
024 import org.apache.camel.impl.ServiceSupport;
025 import org.apache.camel.util.ExchangeHelper;
026 import org.apache.camel.util.ServiceHelper;
027 import org.apache.commons.logging.Log;
028 import org.apache.commons.logging.LogFactory;
029
030 /**
031 * Implements try/catch/finally type processing
032 *
033 * @version $Revision: 36865 $
034 */
035 public class TryProcessor extends ServiceSupport implements Processor {
036 private static final transient Log LOG = LogFactory.getLog(TryProcessor.class);
037
038 private final Processor tryProcessor;
039
040 private final List<CatchProcessor> catchClauses;
041
042 private final Processor finallyProcessor;
043
044 public TryProcessor(Processor tryProcessor, List<CatchProcessor> catchClauses, Processor finallyProcessor) {
045 this.tryProcessor = tryProcessor;
046 this.catchClauses = catchClauses;
047 this.finallyProcessor = finallyProcessor;
048 }
049
050 public String toString() {
051 String finallyText = (finallyProcessor == null) ? "" : " Finally {" + finallyProcessor + "}";
052 return "Try {" + tryProcessor + "} " + catchClauses + finallyText;
053 }
054
055 public void process(Exchange exchange) throws Exception {
056 Throwable e = null;
057 try {
058 tryProcessor.process(exchange);
059 e = exchange.getException();
060
061 // Ignore it if it was handled by the dead letter channel.
062 if (e != null && DeadLetterChannel.isFailureHandled(exchange)) {
063 e = null;
064 }
065 } catch (Throwable ex) {
066 e = ex;
067 exchange.setException(e);
068 }
069
070 Exception unexpected = null;
071 try {
072 if (e != null) {
073 LOG.info("Caught exception while processing exchange.", e);
074 handleException(exchange, e);
075 }
076 } catch (Exception ex) {
077 unexpected = ex;
078 } catch (Throwable ex) {
079 unexpected = new RuntimeCamelException(ex);
080 } finally {
081 try {
082 processFinally(exchange);
083 } catch (Exception ex) {
084 unexpected = ex;
085 } catch (Throwable ex) {
086 unexpected = new RuntimeCamelException(ex);
087 }
088 if (unexpected != null) {
089 LOG.warn("Caught exception inside processFinally clause.", unexpected);
090 throw unexpected;
091 }
092 }
093
094 if (unexpected != null) {
095 LOG.warn("Caught exception inside handle clause.", unexpected);
096 throw unexpected;
097 }
098 }
099
100 protected void doStart() throws Exception {
101 ServiceHelper.startServices(tryProcessor, catchClauses, finallyProcessor);
102 }
103
104 protected void doStop() throws Exception {
105 ServiceHelper.stopServices(tryProcessor, catchClauses, finallyProcessor);
106 }
107
108 protected void handleException(Exchange exchange, Throwable e) throws Throwable {
109 for (CatchProcessor catchClause : catchClauses) {
110 if (catchClause.catches(e)) {
111 // lets attach the exception to the exchange
112 Exchange localExchange = exchange.copy();
113 localExchange.getIn().setHeader("caught.exception", e);
114 // give the rest of the pipeline another chance
115 localExchange.setException(null);
116
117 // do not catch any exception here, let it propagate up
118 catchClause.process(localExchange);
119 localExchange.getIn().removeHeader("caught.exception");
120 ExchangeHelper.copyResults(exchange, localExchange);
121 return;
122 }
123 }
124 }
125
126 protected void processFinally(Exchange exchange) throws Throwable {
127 if (finallyProcessor != null) {
128 Throwable lastException = exchange.getException();
129 exchange.setException(null);
130
131 // do not catch any exception here, let it propagate up
132 finallyProcessor.process(exchange);
133 if (exchange.getException() == null) {
134 exchange.setException(lastException);
135 }
136 }
137 }
138 }