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 }