/*
* Copyright 2002-2008 the original author or authors.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.springframework.orm.jpa.support;
import javax.persistence.EntityManager;
import javax.persistence.PersistenceException;
import org.springframework.dao.DataAccessException;
import org.springframework.dao.DataAccessResourceFailureException;
import org.springframework.orm.jpa.EntityManagerFactoryAccessor;
import org.springframework.orm.jpa.EntityManagerHolder;
import org.springframework.orm.jpa.EntityManagerFactoryUtils;
import org.springframework.transaction.support.TransactionSynchronizationManager;
import org.springframework.ui.ModelMap;
import org.springframework.web.context.request.WebRequest;
import org.springframework.web.context.request.WebRequestInterceptor;
/**
* Spring web request interceptor that binds a JPA EntityManager to the
* thread for the entire processing of the request. Intended for the "Open
* EntityManager in View" pattern, i.e. to allow for lazy loading in
* web views despite the original transactions already being completed.
*
* <p>This interceptor makes JPA EntityManagers available via the current thread,
* which will be autodetected by transaction managers. It is suitable for service
* layer transactions via {@link org.springframework.orm.jpa.JpaTransactionManager}
* or {@link org.springframework.transaction.jta.JtaTransactionManager} as well
* as for non-transactional read-only execution.
*
* <p>In contrast to {@link OpenEntityManagerInViewFilter}, this interceptor
* is set up in a Spring application context and can thus take advantage of
* bean wiring. It inherits common JPA configuration properties from
* {@link org.springframework.orm.jpa.JpaAccessor}, to be configured in a
* bean definition.
*
* @author Juergen Hoeller
* @since 2.0
* @see OpenEntityManagerInViewFilter
* @see org.springframework.orm.jpa.JpaInterceptor
* @see org.springframework.orm.jpa.JpaTransactionManager
* @see org.springframework.orm.jpa.JpaTemplate#execute
* @see org.springframework.orm.jpa.SharedEntityManagerCreator
* @see org.springframework.transaction.support.TransactionSynchronizationManager
*/
public class OpenEntityManagerInViewInterceptor extends EntityManagerFactoryAccessor implements WebRequestInterceptor {
/**
* Suffix that gets appended to the EntityManagerFactory toString
* representation for the "participate in existing entity manager
* handling" request attribute.
* @see #getParticipateAttributeName
*/
public static final String PARTICIPATE_SUFFIX = ".PARTICIPATE";
public void preHandle(WebRequest request) throws DataAccessException {
if (TransactionSynchronizationManager.hasResource(getEntityManagerFactory())) {
// do not modify the EntityManager: just mark the request accordingly
String participateAttributeName = getParticipateAttributeName();
Integer count = (Integer) request.getAttribute(participateAttributeName, WebRequest.SCOPE_REQUEST);
int newCount = (count != null ? count + 1 : 1);
request.setAttribute(getParticipateAttributeName(), newCount, WebRequest.SCOPE_REQUEST);
}
else {
logger.debug("Opening JPA EntityManager in OpenEntityManagerInViewInterceptor");
try {
EntityManager em = createEntityManager();
TransactionSynchronizationManager.bindResource(getEntityManagerFactory(), new EntityManagerHolder(em));
}
catch (PersistenceException ex) {
throw new DataAccessResourceFailureException("Could not create JPA EntityManager", ex);
}
}
}
public void postHandle(WebRequest request, ModelMap model) {
}
public void afterCompletion(WebRequest request, Exception ex) throws DataAccessException {
String participateAttributeName = getParticipateAttributeName();
Integer count = (Integer) request.getAttribute(participateAttributeName, WebRequest.SCOPE_REQUEST);
if (count != null) {
// Do not modify the EntityManager: just clear the marker.
if (count > 1) {
request.setAttribute(participateAttributeName, count - 1, WebRequest.SCOPE_REQUEST);
}
else {
request.removeAttribute(participateAttributeName, WebRequest.SCOPE_REQUEST);
}
}
else {
EntityManagerHolder emHolder = (EntityManagerHolder)
TransactionSynchronizationManager.unbindResource(getEntityManagerFactory());
logger.debug("Closing JPA EntityManager in OpenEntityManagerInViewInterceptor");
EntityManagerFactoryUtils.closeEntityManager(emHolder.getEntityManager());
}
}
/**
* Return the name of the request attribute that identifies that a request is
* already filtered. Default implementation takes the toString representation
* of the EntityManagerFactory instance and appends ".FILTERED".
* @see #PARTICIPATE_SUFFIX
*/
protected String getParticipateAttributeName() {
return getEntityManagerFactory().toString() + PARTICIPATE_SUFFIX;
}
}
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