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.bam.processor; 018 019 import org.apache.camel.Exchange; 020 import org.apache.camel.Expression; 021 import org.apache.camel.Processor; 022 import org.apache.camel.RuntimeCamelException; 023 import org.apache.commons.logging.Log; 024 import org.apache.commons.logging.LogFactory; 025 import org.springframework.transaction.TransactionStatus; 026 import org.springframework.transaction.support.TransactionCallback; 027 import org.springframework.transaction.support.TransactionTemplate; 028 029 import java.lang.reflect.ParameterizedType; 030 import java.lang.reflect.Type; 031 032 /** 033 * A base {@link Processor} for working on 034 * <a href="http://activemq.apache.org/camel/bam.html">BAM</a> which a derived class would do the actual 035 * persistence such as the {@link JpaBamProcessor} 036 * 037 * @version $Revision: $ 038 */ 039 public abstract class BamProcessorSupport<T> implements Processor { 040 private static final transient Log log = LogFactory.getLog(BamProcessorSupport.class); 041 private Class<T> entityType; 042 private Expression<Exchange> correlationKeyExpression; 043 private TransactionTemplate transactionTemplate; 044 045 protected BamProcessorSupport(TransactionTemplate transactionTemplate, Expression<Exchange> correlationKeyExpression) { 046 this.transactionTemplate = transactionTemplate; 047 this.correlationKeyExpression = correlationKeyExpression; 048 049 Type type = getClass().getGenericSuperclass(); 050 if (type instanceof ParameterizedType) { 051 ParameterizedType parameterizedType = (ParameterizedType) type; 052 Type[] arguments = parameterizedType.getActualTypeArguments(); 053 if (arguments.length > 0) { 054 Type argumentType = arguments[0]; 055 if (argumentType instanceof Class) { 056 this.entityType = (Class<T>) argumentType; 057 } 058 } 059 } 060 if (entityType == null) { 061 throw new IllegalArgumentException("Could not infer the entity type!"); 062 } 063 } 064 065 protected BamProcessorSupport(TransactionTemplate transactionTemplate, Expression<Exchange> correlationKeyExpression, Class<T> entitytype) { 066 this.transactionTemplate = transactionTemplate; 067 this.entityType = entitytype; 068 this.correlationKeyExpression = correlationKeyExpression; 069 } 070 071 public void process(final Exchange exchange) { 072 transactionTemplate.execute(new TransactionCallback() { 073 public Object doInTransaction(TransactionStatus status) { 074 try { 075 Object key = getCorrelationKey(exchange); 076 077 T entity = loadEntity(exchange, key); 078 079 if (log.isDebugEnabled()) { 080 log.debug("Correlation key: " + key + " with entity: " + entity); 081 } 082 processEntity(exchange, entity); 083 084 return entity; 085 } 086 catch (Exception e) { 087 throw new RuntimeCamelException(e); 088 } 089 } 090 }); 091 } 092 093 // Properties 094 //----------------------------------------------------------------------- 095 public Expression<Exchange> getCorrelationKeyExpression() { 096 return correlationKeyExpression; 097 } 098 099 public Class<T> getEntityType() { 100 return entityType; 101 } 102 103 // Implemenation methods 104 //----------------------------------------------------------------------- 105 protected abstract void processEntity(Exchange exchange, T entity) throws Exception; 106 107 protected abstract T loadEntity(Exchange exchange, Object key); 108 109 protected Object getCorrelationKey(Exchange exchange) throws NoCorrelationKeyException { 110 Object value = correlationKeyExpression.evaluate(exchange); 111 if (value == null) { 112 throw new NoCorrelationKeyException(this, exchange); 113 } 114 return value; 115 } 116 }