1 /* 2 * Copyright 2002-2008 the original author or authors. 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 17 package org.springframework.orm.jpa.support; 18 19 import javax.persistence.EntityManager; 20 import javax.persistence.PersistenceException; 21 22 import org.springframework.dao.DataAccessException; 23 import org.springframework.dao.DataAccessResourceFailureException; 24 import org.springframework.orm.jpa.EntityManagerFactoryAccessor; 25 import org.springframework.orm.jpa.EntityManagerHolder; 26 import org.springframework.orm.jpa.EntityManagerFactoryUtils; 27 import org.springframework.transaction.support.TransactionSynchronizationManager; 28 import org.springframework.ui.ModelMap; 29 import org.springframework.web.context.request.WebRequest; 30 import org.springframework.web.context.request.WebRequestInterceptor; 31 32 /** 33 * Spring web request interceptor that binds a JPA EntityManager to the 34 * thread for the entire processing of the request. Intended for the "Open 35 * EntityManager in View" pattern, i.e. to allow for lazy loading in 36 * web views despite the original transactions already being completed. 37 * 38 * <p>This interceptor makes JPA EntityManagers available via the current thread, 39 * which will be autodetected by transaction managers. It is suitable for service 40 * layer transactions via {@link org.springframework.orm.jpa.JpaTransactionManager} 41 * or {@link org.springframework.transaction.jta.JtaTransactionManager} as well 42 * as for non-transactional read-only execution. 43 * 44 * <p>In contrast to {@link OpenEntityManagerInViewFilter}, this interceptor 45 * is set up in a Spring application context and can thus take advantage of 46 * bean wiring. It inherits common JPA configuration properties from 47 * {@link org.springframework.orm.jpa.JpaAccessor}, to be configured in a 48 * bean definition. 49 * 50 * @author Juergen Hoeller 51 * @since 2.0 52 * @see OpenEntityManagerInViewFilter 53 * @see org.springframework.orm.jpa.JpaInterceptor 54 * @see org.springframework.orm.jpa.JpaTransactionManager 55 * @see org.springframework.orm.jpa.JpaTemplate#execute 56 * @see org.springframework.orm.jpa.SharedEntityManagerCreator 57 * @see org.springframework.transaction.support.TransactionSynchronizationManager 58 */ 59 public class OpenEntityManagerInViewInterceptor extends EntityManagerFactoryAccessor implements WebRequestInterceptor { 60 61 /** 62 * Suffix that gets appended to the EntityManagerFactory toString 63 * representation for the "participate in existing entity manager 64 * handling" request attribute. 65 * @see #getParticipateAttributeName 66 */ 67 public static final String PARTICIPATE_SUFFIX = ".PARTICIPATE"; 68 69 preHandle(WebRequest request)70 public void preHandle(WebRequest request) throws DataAccessException { 71 if (TransactionSynchronizationManager.hasResource(getEntityManagerFactory())) { 72 // do not modify the EntityManager: just mark the request accordingly 73 String participateAttributeName = getParticipateAttributeName(); 74 Integer count = (Integer) request.getAttribute(participateAttributeName, WebRequest.SCOPE_REQUEST); 75 int newCount = (count != null ? count + 1 : 1); 76 request.setAttribute(getParticipateAttributeName(), newCount, WebRequest.SCOPE_REQUEST); 77 } 78 else { 79 logger.debug("Opening JPA EntityManager in OpenEntityManagerInViewInterceptor"); 80 try { 81 EntityManager em = createEntityManager(); 82 TransactionSynchronizationManager.bindResource(getEntityManagerFactory(), new EntityManagerHolder(em)); 83 } 84 catch (PersistenceException ex) { 85 throw new DataAccessResourceFailureException("Could not create JPA EntityManager", ex); 86 } 87 } 88 } 89 postHandle(WebRequest request, ModelMap model)90 public void postHandle(WebRequest request, ModelMap model) { 91 } 92 afterCompletion(WebRequest request, Exception ex)93 public void afterCompletion(WebRequest request, Exception ex) throws DataAccessException { 94 String participateAttributeName = getParticipateAttributeName(); 95 Integer count = (Integer) request.getAttribute(participateAttributeName, WebRequest.SCOPE_REQUEST); 96 if (count != null) { 97 // Do not modify the EntityManager: just clear the marker. 98 if (count > 1) { 99 request.setAttribute(participateAttributeName, count - 1, WebRequest.SCOPE_REQUEST); 100 } 101 else { 102 request.removeAttribute(participateAttributeName, WebRequest.SCOPE_REQUEST); 103 } 104 } 105 else { 106 EntityManagerHolder emHolder = (EntityManagerHolder) 107 TransactionSynchronizationManager.unbindResource(getEntityManagerFactory()); 108 logger.debug("Closing JPA EntityManager in OpenEntityManagerInViewInterceptor"); 109 EntityManagerFactoryUtils.closeEntityManager(emHolder.getEntityManager()); 110 } 111 } 112 113 /** 114 * Return the name of the request attribute that identifies that a request is 115 * already filtered. Default implementation takes the toString representation 116 * of the EntityManagerFactory instance and appends ".FILTERED". 117 * @see #PARTICIPATE_SUFFIX 118 */ getParticipateAttributeName()119 protected String getParticipateAttributeName() { 120 return getEntityManagerFactory().toString() + PARTICIPATE_SUFFIX; 121 } 122 123 } 124