src/commons/org/codehaus/groovy/grails/orm/support/TransactionManagerPostProcessor.java

   1 /*
   2  * Copyright 2004-2006 Graeme Rocher
   3  *
   4  * Licensed under the Apache License, Version 2.0 (the "License");
   5  * you may not use this file except in compliance with the License.
   6  * You may obtain a copy of the License at
   7  *
   8  *      http://www.apache.org/licenses/LICENSE-2.0
   9  *
  10  * Unless required by applicable law or agreed to in writing, software
  11  * distributed under the License is distributed on an "AS IS" BASIS,
  12  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  13  * See the License for the specific language governing permissions and
  14  * limitations under the License.
  15  */
  16 package org.codehaus.groovy.grails.orm.support;
  17
  18 import org.springframework.beans.BeansException;
  19 import org.springframework.beans.factory.BeanFactory;
  20 import org.springframework.beans.factory.BeanFactoryAware;
  21 import org.springframework.beans.factory.BeanFactoryUtils;
  22 import org.springframework.beans.factory.config.ConfigurableListableBeanFactory;
  23 import org.springframework.beans.factory.config.InstantiationAwareBeanPostProcessorAdapter;
  24 import org.springframework.transaction.PlatformTransactionManager;
  25
  26 /**
  27  * This is a bean post processor that injects the platform transaction
  28  * manager into beans that implement the {@link TransactionManagerAware}
  29  * interface.
  30  * @author Graeme Rocher
  31  * @since 0.4
  32  */
  33 public class TransactionManagerPostProcessor extends InstantiationAwareBeanPostProcessorAdapter implements BeanFactoryAware {
  34     private ConfigurableListableBeanFactory beanFactory;
  35     private PlatformTransactionManager transactionManager;
  36     private boolean initialized = false;
  37
  38     /**
  39      * Gets the platform transaction manager from the bean factory if
  40      * there is one.
  41      * @param beanFactory The bean factory handling this post processor.
  42      * @throws BeansException
  43      */
  44     public void setBeanFactory(BeanFactory beanFactory) throws BeansException {
  45         if (!(beanFactory instanceof ConfigurableListableBeanFactory)) {
  46             throw new IllegalArgumentException(
  47                     "TransactionManagerPostProcessor requires a ConfigurableListableBeanFactory");
  48             }
  49
  50             this.beanFactory = (ConfigurableListableBeanFactory) beanFactory;
  51     }
  52
  53     /**
  54      * Injects the platform transaction manager into the given bean if
  55      * that bean implements the {@link TransactionManagerAware} interface.
  56      * @param bean The bean to process.
  57      * @param name The name of the bean.
  58      * @return The bean after the transaction manager has been injected.
  59      * @throws BeansException
  60      */
  61     public synchronized boolean postProcessAfterInstantiation(Object bean, String name) throws BeansException {
  62         // Lazily retrieve the transaction manager from the bean factory.
  63         // Attempting to retrieve it within 'setBeanFactory()' blocks
  64         // other bean post processors from processing the beans in the
  65         // factory!
  66         if (!this.initialized) {
  67             // Fetch the names of all the beans that are of type
  68             // PlatformTransactionManager. Note that we have to pass
  69             // "false" for the last argument to avoid eager initialisation,
  70             // otherwise we end up in an endless loop (it triggers the
  71             // current method).
  72             String[] beanNames = BeanFactoryUtils.beanNamesForTypeIncludingAncestors(
  73                     this.beanFactory,
  74                     PlatformTransactionManager.class,
  75                     false,
  76                     false);
  77
  78             // If at least one is found, use the first of them as the
  79             // transaction manager for the application.
  80             if (beanNames.length > 0) {
  81                 this.transactionManager = (PlatformTransactionManager)beanFactory.getBean(beanNames[0]);
  82             }
  83
  84             // Don't attempt to retrieve the transaction manager again.
  85             this.initialized = true;
  86         }
  87
  88         if (bean instanceof TransactionManagerAware) {
  89             TransactionManagerAware tma = (TransactionManagerAware) bean;
  90             tma.setTransactionManager(this.transactionManager);
  91         }
  92         return true;
  93     }
  94 }