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.Iterator;
020 import java.util.List;
021
022 import org.apache.camel.Exchange;
023 import org.apache.camel.Predicate;
024 import org.apache.camel.Processor;
025 import org.apache.camel.util.ObjectHelper;
026
027 /**
028 * A processor which catches exceptions.
029 *
030 * @version $Revision: 881198 $
031 */
032 public class CatchProcessor extends DelegateProcessor implements Traceable {
033 private final List<Class> exceptions;
034 private final Predicate onWhen;
035 private final Predicate handled;
036
037 public CatchProcessor(List<Class> exceptions, Processor processor, Predicate onWhen, Predicate handled) {
038 super(processor);
039 this.exceptions = exceptions;
040 this.onWhen = onWhen;
041 this.handled = handled;
042 }
043
044 @Override
045 public String toString() {
046 return "Catch[" + exceptions + " -> " + getProcessor() + "]";
047 }
048
049 public String getTraceLabel() {
050 return "catch";
051 }
052
053 /**
054 * Returns with the exception that is caught by this processor.
055 *
056 * This method traverses exception causes, so sometimes the exception
057 * returned from this method might be one of causes of the parameter
058 * passed.
059 *
060 * @param exchange the current exchange
061 * @param exception the thrown exception
062 * @return Throwable that this processor catches. <tt>null</tt> if nothing matches.
063 */
064 public Throwable catches(Exchange exchange, Throwable exception) {
065 // use the exception iterator to walk the caused by hierarchy
066 Iterator<Throwable> it = ObjectHelper.createExceptionIterator(exception);
067 while (it.hasNext()) {
068 Throwable e = it.next();
069 // see if we catch this type
070 for (Class<?> type : exceptions) {
071 if (type.isInstance(e) && matchesWhen(exchange)) {
072 return e;
073 }
074 }
075 }
076
077 // not found
078 return null;
079 }
080
081
082 /**
083 * Whether this catch processor handles the exception it have caught
084 *
085 * @param exchange the current exchange
086 * @return <tt>true</tt> if this processor handles it, <tt>false</tt> otherwise.
087 */
088 public boolean handles(Exchange exchange) {
089 if (handled == null) {
090 // handle by default
091 return true;
092 }
093
094 return handled.matches(exchange);
095 }
096
097 public List<Class> getExceptions() {
098 return exceptions;
099 }
100
101 /**
102 * Strategy method for matching the exception type with the current exchange.
103 * <p/>
104 * This default implementation will match as:
105 * <ul>
106 * <li>Always true if no when predicate on the exception type
107 * <li>Otherwise the when predicate is matches against the current exchange
108 * </ul>
109 *
110 * @param exchange the current {@link org.apache.camel.Exchange}
111 * @return <tt>true</tt> if matched, <tt>false</tt> otherwise.
112 */
113 protected boolean matchesWhen(Exchange exchange) {
114 if (onWhen == null) {
115 // if no predicate then it's always a match
116 return true;
117 }
118 return onWhen.matches(exchange);
119 }
120 }