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.LinkedHashMap;
020    import java.util.List;
021    import java.util.Map;
022    
023    import org.apache.camel.Exchange;
024    import org.apache.camel.Processor;
025    import org.apache.camel.impl.ServiceSupport;
026    import org.apache.camel.model.ExceptionType;
027    import org.apache.camel.processor.exceptionpolicy.DefaultExceptionPolicyStrategy;
028    import org.apache.camel.processor.exceptionpolicy.ExceptionPolicyStrategy;
029    
030    /**
031     * Support class for {@link ErrorHandler} implementations.
032     *
033     * @version $Revision: 37863 $
034     */
035    public abstract class ErrorHandlerSupport extends ServiceSupport implements ErrorHandler {
036        private Map<Class, ExceptionType> exceptionPolicies = new LinkedHashMap<Class, ExceptionType>();
037        private ExceptionPolicyStrategy exceptionPolicy = createDefaultExceptionPolicyStrategy();
038    
039        public void addExceptionPolicy(ExceptionType exception) {
040            Processor processor = exception.getErrorHandler();
041            addChildService(processor);
042    
043            List<Class> list = exception.getExceptionClasses();
044    
045            for (Class exceptionType : list) {
046                exceptionPolicies.put(exceptionType, exception);
047            }
048        }
049    
050        /**
051         * Attempts to invoke the handler for this particular exception if one is available
052         */
053        protected boolean customProcessorForException(Exchange exchange, Throwable exception) throws Exception {
054            ExceptionType policy = getExceptionPolicy(exchange, exception);
055            if (policy != null) {
056                Processor processor = policy.getErrorHandler();
057                if (processor != null) {
058                    processor.process(exchange);
059                    return true;
060                }
061            }
062            return false;
063        }
064    
065        /**
066         * Attempts to find the best suited {@link ExceptionType} to be used for handling the given thrown exception.
067         *
068         * @param exchange  the exchange
069         * @param exception the exception that was thrown
070         * @return the best exception type to handle this exception, <tt>null</tt> if none found.
071         */
072        protected ExceptionType getExceptionPolicy(Exchange exchange, Throwable exception) {
073            if (exceptionPolicy == null) {
074                throw new IllegalStateException("The exception policy has not been set");
075            }
076    
077            return exceptionPolicy.getExceptionPolicy(exceptionPolicies, exchange, exception);
078        }
079    
080        /**
081         * Sets the strategy to use for resolving the {@link ExceptionType} to use
082         * for handling thrown exceptions.
083         */
084        public void setExceptionPolicy(ExceptionPolicyStrategy exceptionPolicy) {
085            this.exceptionPolicy = exceptionPolicy;
086        }
087    
088        /**
089         * Creates the default exception policy strategy to use.
090         */
091        public static ExceptionPolicyStrategy createDefaultExceptionPolicyStrategy() {
092            return new DefaultExceptionPolicyStrategy();
093        }
094    
095    }