/*
* Copyright 2002-2011 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.hibernate4.support;
import java.io.IOException;
import javax.servlet.FilterChain;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import org.hibernate.FlushMode;
import org.hibernate.HibernateException;
import org.hibernate.Session;
import org.hibernate.SessionFactory;
import org.springframework.dao.DataAccessResourceFailureException;
import org.springframework.orm.hibernate4.SessionFactoryUtils;
import org.springframework.orm.hibernate4.SessionHolder;
import org.springframework.transaction.support.TransactionSynchronizationManager;
import org.springframework.web.context.WebApplicationContext;
import org.springframework.web.context.support.WebApplicationContextUtils;
import org.springframework.web.filter.OncePerRequestFilter;
/**
* Servlet 2.3 Filter that binds a Hibernate Session to the thread for the entire
* processing of the request. Intended for the "Open Session in View" pattern,
* i.e. to allow for lazy loading in web views despite the original transactions
* already being completed.
*
* <p>This filter makes Hibernate Sessions available via the current thread, which
* will be autodetected by transaction managers. It is suitable for service layer
* transactions via {@link org.springframework.orm.hibernate4.HibernateTransactionManager}
* as well as for non-transactional execution (if configured appropriately).
*
* <p><b>NOTE</b>: This filter will by default <i>not</i> flush the Hibernate Session,
* with the flush mode set to <code>FlushMode.NEVER</code>. It assumes to be used
* in combination with service layer transactions that care for the flushing: The
* active transaction manager will temporarily change the flush mode to
* <code>FlushMode.AUTO</code> during a read-write transaction, with the flush
* mode reset to <code>FlushMode.NEVER</code> at the end of each transaction.
*
* <p><b>WARNING:</b> Applying this filter to existing logic can cause issues that
* have not appeared before, through the use of a single Hibernate Session for the
* processing of an entire request. In particular, the reassociation of persistent
* objects with a Hibernate Session has to occur at the very beginning of request
* processing, to avoid clashes with already loaded instances of the same objects.
*
* <p>Looks up the SessionFactory in Spring's root web application context.
* Supports a "sessionFactoryBeanName" filter init-param in <code>web.xml</code>;
* the default bean name is "sessionFactory". Looks up the SessionFactory on each
* request, to avoid initialization order issues (when using ContextLoaderServlet,
* the root application context will get initialized <i>after</i> this filter).
*
* @author Juergen Hoeller
* @since 3.1
* @see #lookupSessionFactory
* @see OpenSessionInViewInterceptor
* @see org.springframework.orm.hibernate4.HibernateTransactionManager
* @see org.springframework.transaction.support.TransactionSynchronizationManager
*/
public class OpenSessionInViewFilter extends OncePerRequestFilter {
public static final String DEFAULT_SESSION_FACTORY_BEAN_NAME = "sessionFactory";
private String sessionFactoryBeanName = DEFAULT_SESSION_FACTORY_BEAN_NAME;
/**
* Set the bean name of the SessionFactory to fetch from Spring's
* root application context. Default is "sessionFactory".
* @see #DEFAULT_SESSION_FACTORY_BEAN_NAME
*/
public void setSessionFactoryBeanName(String sessionFactoryBeanName) {
this.sessionFactoryBeanName = sessionFactoryBeanName;
}
/**
* Return the bean name of the SessionFactory to fetch from Spring's
* root application context.
*/
protected String getSessionFactoryBeanName() {
return this.sessionFactoryBeanName;
}
@Override
protected void doFilterInternal(
HttpServletRequest request, HttpServletResponse response, FilterChain filterChain)
throws ServletException, IOException {
SessionFactory sessionFactory = lookupSessionFactory(request);
boolean participate = false;
if (TransactionSynchronizationManager.hasResource(sessionFactory)) {
// Do not modify the Session: just set the participate flag.
participate = true;
}
else {
logger.debug("Opening Hibernate Session in OpenSessionInViewFilter");
Session session = openSession(sessionFactory);
TransactionSynchronizationManager.bindResource(sessionFactory, new SessionHolder(session));
}
try {
filterChain.doFilter(request, response);
}
finally {
if (!participate) {
SessionHolder sessionHolder =
(SessionHolder) TransactionSynchronizationManager.unbindResource(sessionFactory);
logger.debug("Closing Hibernate Session in OpenSessionInViewFilter");
SessionFactoryUtils.closeSession(sessionHolder.getSession());
}
}
}
/**
* Look up the SessionFactory that this filter should use,
* taking the current HTTP request as argument.
* <p>The default implementation delegates to the {@link #lookupSessionFactory()}
* variant without arguments.
* @param request the current request
* @return the SessionFactory to use
*/
protected SessionFactory lookupSessionFactory(HttpServletRequest request) {
return lookupSessionFactory();
}
/**
* Look up the SessionFactory that this filter should use.
* <p>The default implementation looks for a bean with the specified name
* in Spring's root application context.
* @return the SessionFactory to use
* @see #getSessionFactoryBeanName
*/
protected SessionFactory lookupSessionFactory() {
if (logger.isDebugEnabled()) {
logger.debug("Using SessionFactory '" + getSessionFactoryBeanName() + "' for OpenSessionInViewFilter");
}
WebApplicationContext wac = WebApplicationContextUtils.getRequiredWebApplicationContext(getServletContext());
return wac.getBean(getSessionFactoryBeanName(), SessionFactory.class);
}
/**
* Open a Session for the SessionFactory that this filter uses.
* <p>The default implementation delegates to the
* <code>SessionFactory.openSession</code> method and
* sets the <code>Session</code>'s flush mode to "MANUAL".
* @param sessionFactory the SessionFactory that this filter uses
* @return the Session to use
* @throws DataAccessResourceFailureException if the Session could not be created
* @see org.hibernate.FlushMode#MANUAL
*/
protected Session openSession(SessionFactory sessionFactory) throws DataAccessResourceFailureException {
try {
Session session = SessionFactoryUtils.openSession(sessionFactory);
session.setFlushMode(FlushMode.MANUAL);
return session;
}
catch (HibernateException ex) {
throw new DataAccessResourceFailureException("Could not open Hibernate Session", ex);
}
}
}