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.exceptionpolicy; 018 019 import java.util.Map; 020 import java.util.Set; 021 022 import org.apache.camel.Exchange; 023 import org.apache.camel.model.ExceptionType; 024 import org.apache.commons.logging.Log; 025 import org.apache.commons.logging.LogFactory; 026 027 /** 028 * The default strategy used in Camel to resolve the {@link org.apache.camel.model.ExceptionType} that should 029 * handle the thrown exception. 030 * <p/> 031 * This strategy applies the following rules: 032 * <ul> 033 * <li>The exception type must be configured with an Exception that is an instance of the thrown exception</li> 034 * <li>If the exception type has exactly the thrown exception then its selected</li> 035 * <li>Otherwise the type that has an exception that is super of the thrown exception is selected 036 * (recurring up the exception hierarchy) 037 * </ul> 038 */ 039 public class DefaultExceptionPolicyStrategy implements ExceptionPolicyStrategy { 040 041 private static final transient Log LOG = LogFactory.getLog(DefaultExceptionPolicyStrategy.class); 042 043 public ExceptionType getExceptionPolicy(Map<Class, ExceptionType> exceptionPolicices, Exchange exchange, 044 Throwable exception) { 045 // the goal is to find the exception with the same/closet inheritance level as the target exception being thrown 046 int targetLevel = getInheritanceLevel(exception.getClass()); 047 // candidate is the best candidate found so far to return 048 ExceptionType candidate = null; 049 // difference in inheritance level between the current candidate and the thrown exception (target level) 050 int candidateDiff = Integer.MAX_VALUE; 051 052 // loop through all the entries and find the best candidates to use 053 Set<Map.Entry<Class, ExceptionType>> entries = exceptionPolicices.entrySet(); 054 for (Map.Entry<Class, ExceptionType> entry : entries) { 055 Class clazz = entry.getKey(); 056 ExceptionType type = entry.getValue(); 057 058 // must be instance of check to ensure that the clazz is one type of the thrown exception 059 if (clazz.isInstance(exception)) { 060 061 // exact match 062 if (clazz.equals(exception.getClass())) { 063 candidate = type; 064 break; 065 } 066 067 // not an exact match so find the best candidate 068 int level = getInheritanceLevel(clazz); 069 int diff = targetLevel - level; 070 071 if (diff < candidateDiff) { 072 // replace with a much better candidate 073 candidate = type; 074 candidateDiff = diff; 075 } 076 } 077 } 078 079 if (LOG.isDebugEnabled()) { 080 LOG.debug("Using " + candidate + " as the exception policy"); 081 } 082 return candidate; 083 084 } 085 086 private static int getInheritanceLevel(Class clazz) { 087 if (clazz == null || "java.lang.Object".equals(clazz.getName())) { 088 return 0; 089 } 090 return 1 + getInheritanceLevel(clazz.getSuperclass()); 091 } 092 093 }