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 */ 017package org.apache.camel.processor; 018 019import java.util.List; 020 021import org.apache.camel.AsyncCallback; 022import org.apache.camel.Exchange; 023import org.apache.camel.Predicate; 024import org.apache.camel.Processor; 025import org.apache.camel.Traceable; 026import org.apache.camel.spi.IdAware; 027import org.apache.camel.util.EventHelper; 028import org.apache.camel.util.ExchangeHelper; 029import org.apache.camel.util.ObjectHelper; 030import org.slf4j.Logger; 031import org.slf4j.LoggerFactory; 032 033/** 034 * A processor which catches exceptions. 035 * 036 * @version 037 */ 038public class CatchProcessor extends DelegateAsyncProcessor implements Traceable, IdAware { 039 private static final Logger LOG = LoggerFactory.getLogger(CatchProcessor.class); 040 041 private String id; 042 private final List<Class<? extends Throwable>> exceptions; 043 private final Predicate onWhen; 044 private final Predicate handled; 045 046 public CatchProcessor(List<Class<? extends Throwable>> exceptions, Processor processor, Predicate onWhen, Predicate handled) { 047 super(processor); 048 this.exceptions = exceptions; 049 this.onWhen = onWhen; 050 this.handled = handled; 051 } 052 053 @Override 054 public String toString() { 055 return "Catch[" + exceptions + " -> " + getProcessor() + "]"; 056 } 057 058 public String getId() { 059 return id; 060 } 061 062 public void setId(String id) { 063 this.id = id; 064 } 065 066 public String getTraceLabel() { 067 return "catch"; 068 } 069 070 @Override 071 public boolean process(final Exchange exchange, final AsyncCallback callback) { 072 Exception e = exchange.getException(); 073 Throwable caught = catches(exchange, e); 074 // If a previous catch clause handled the exception or if this clause does not match, exit 075 if (exchange.getProperty(Exchange.EXCEPTION_HANDLED) != null || caught == null) { 076 callback.done(true); 077 return true; 078 } 079 if (LOG.isTraceEnabled()) { 080 LOG.trace("This CatchProcessor catches the exception: {} caused by: {}", caught.getClass().getName(), e.getMessage()); 081 } 082 083 // store the last to endpoint as the failure endpoint 084 if (exchange.getProperty(Exchange.FAILURE_ENDPOINT) == null) { 085 exchange.setProperty(Exchange.FAILURE_ENDPOINT, exchange.getProperty(Exchange.TO_ENDPOINT)); 086 } 087 // give the rest of the pipeline another chance 088 exchange.setProperty(Exchange.EXCEPTION_HANDLED, true); 089 exchange.setProperty(Exchange.EXCEPTION_CAUGHT, e); 090 exchange.setException(null); 091 // and we should not be regarded as exhausted as we are in a try .. catch block 092 exchange.removeProperty(Exchange.REDELIVERY_EXHAUSTED); 093 094 // is the exception handled by the catch clause 095 final boolean handled = handles(exchange); 096 097 if (LOG.isDebugEnabled()) { 098 LOG.debug("The exception is handled: {} for the exception: {} caused by: {}", 099 new Object[]{handled, e.getClass().getName(), e.getMessage()}); 100 } 101 102 if (handled) { 103 // emit event that the failure is being handled 104 EventHelper.notifyExchangeFailureHandling(exchange.getContext(), exchange, processor, false, null); 105 } 106 107 boolean sync = processor.process(exchange, new AsyncCallback() { 108 public void done(boolean doneSync) { 109 if (handled) { 110 // emit event that the failure was handled 111 EventHelper.notifyExchangeFailureHandled(exchange.getContext(), exchange, processor, false, null); 112 } else { 113 if (exchange.getException() == null) { 114 exchange.setException(exchange.getProperty(Exchange.EXCEPTION_CAUGHT, Exception.class)); 115 } 116 } 117 // always clear redelivery exhausted in a catch clause 118 exchange.removeProperty(Exchange.REDELIVERY_EXHAUSTED); 119 120 if (!doneSync) { 121 // signal callback to continue routing async 122 ExchangeHelper.prepareOutToIn(exchange); 123 } 124 125 callback.done(doneSync); 126 } 127 }); 128 129 return sync; 130 } 131 132 /** 133 * Returns with the exception that is caught by this processor. 134 * 135 * This method traverses exception causes, so sometimes the exception 136 * returned from this method might be one of causes of the parameter 137 * passed. 138 * 139 * @param exchange the current exchange 140 * @param exception the thrown exception 141 * @return Throwable that this processor catches. <tt>null</tt> if nothing matches. 142 */ 143 protected Throwable catches(Exchange exchange, Throwable exception) { 144 // use the exception iterator to walk the caused by hierarchy 145 for (final Throwable e : ObjectHelper.createExceptionIterable(exception)) { 146 // see if we catch this type 147 for (final Class<?> type : exceptions) { 148 if (type.isInstance(e) && matchesWhen(exchange)) { 149 return e; 150 } 151 } 152 } 153 154 // not found 155 return null; 156 } 157 158 /** 159 * Whether this catch processor handles the exception it have caught 160 * 161 * @param exchange the current exchange 162 * @return <tt>true</tt> if this processor handles it, <tt>false</tt> otherwise. 163 */ 164 protected boolean handles(Exchange exchange) { 165 if (handled == null) { 166 // handle by default 167 return true; 168 } 169 170 return handled.matches(exchange); 171 } 172 173 public List<Class<? extends Throwable>> getExceptions() { 174 return exceptions; 175 } 176 177 /** 178 * Strategy method for matching the exception type with the current exchange. 179 * <p/> 180 * This default implementation will match as: 181 * <ul> 182 * <li>Always true if no when predicate on the exception type 183 * <li>Otherwise the when predicate is matches against the current exchange 184 * </ul> 185 * 186 * @param exchange the current {@link org.apache.camel.Exchange} 187 * @return <tt>true</tt> if matched, <tt>false</tt> otherwise. 188 */ 189 protected boolean matchesWhen(Exchange exchange) { 190 if (onWhen == null) { 191 // if no predicate then it's always a match 192 return true; 193 } 194 return onWhen.matches(exchange); 195 } 196}