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.Traceable;
026 import org.apache.camel.util.ObjectHelper;
027
028 /**
029 * A processor which catches exceptions.
030 *
031 * @version
032 */
033 public class CatchProcessor extends DelegateAsyncProcessor implements Traceable {
034 private final List<Class<? extends Throwable>> exceptions;
035 private final Predicate onWhen;
036 private final Predicate handled;
037
038 public CatchProcessor(List<Class<? extends Throwable>> exceptions, Processor processor, Predicate onWhen, Predicate handled) {
039 super(processor);
040 this.exceptions = exceptions;
041 this.onWhen = onWhen;
042 this.handled = handled;
043 }
044
045 @Override
046 public String toString() {
047 return "Catch[" + exceptions + " -> " + getProcessor() + "]";
048 }
049
050 public String getTraceLabel() {
051 return "catch";
052 }
053
054 /**
055 * Returns with the exception that is caught by this processor.
056 *
057 * This method traverses exception causes, so sometimes the exception
058 * returned from this method might be one of causes of the parameter
059 * passed.
060 *
061 * @param exchange the current exchange
062 * @param exception the thrown exception
063 * @return Throwable that this processor catches. <tt>null</tt> if nothing matches.
064 */
065 public Throwable catches(Exchange exchange, Throwable exception) {
066 // use the exception iterator to walk the caused by hierarchy
067 Iterator<Throwable> it = ObjectHelper.createExceptionIterator(exception);
068 while (it.hasNext()) {
069 Throwable e = it.next();
070 // see if we catch this type
071 for (Class<?> type : exceptions) {
072 if (type.isInstance(e) && matchesWhen(exchange)) {
073 return e;
074 }
075 }
076 }
077
078 // not found
079 return null;
080 }
081
082
083 /**
084 * Whether this catch processor handles the exception it have caught
085 *
086 * @param exchange the current exchange
087 * @return <tt>true</tt> if this processor handles it, <tt>false</tt> otherwise.
088 */
089 public boolean handles(Exchange exchange) {
090 if (handled == null) {
091 // handle by default
092 return true;
093 }
094
095 return handled.matches(exchange);
096 }
097
098 public List<Class<? extends Throwable>> getExceptions() {
099 return exceptions;
100 }
101
102 /**
103 * Strategy method for matching the exception type with the current exchange.
104 * <p/>
105 * This default implementation will match as:
106 * <ul>
107 * <li>Always true if no when predicate on the exception type
108 * <li>Otherwise the when predicate is matches against the current exchange
109 * </ul>
110 *
111 * @param exchange the current {@link org.apache.camel.Exchange}
112 * @return <tt>true</tt> if matched, <tt>false</tt> otherwise.
113 */
114 protected boolean matchesWhen(Exchange exchange) {
115 if (onWhen == null) {
116 // if no predicate then it's always a match
117 return true;
118 }
119 return onWhen.matches(exchange);
120 }
121 }