[Springframework-developer] OpenSessionInViewFilter

[Artem P. <bla...@ca...>]

  Some Web application frameworks like JSF might require you to extend the
lifetime of a persistent entity beyond a single HTTP request. What I am
proposing is an alternative implementation of OpenSessionInViewFilter that
opens one Hibernate session per HTTP session instead of one session per
request. JDBC connection management should not be a problem because it is
possible to disconnect and reconnect Hibernate sessions without closing
them.

Here is the filter that I'm using in my application... I think it would be a
good idea to include something similar in a future release of Spring. Please
note that it hasn't been well tested, and it requires a session filter that
closes orphaned sessions.

public class HibernateSessionFilter extends OncePerRequestFilter {
 public static final String DEFAULT_SESSION_FACTORY_BEAN_NAME =
"sessionFactory";
 public static final String SESSION_KEY = "org.foo.web.hibernateSession";

 private String sessionFactoryBeanName = DEFAULT_SESSION_FACTORY_BEAN_NAME;

 /**
  * @return Returns the sessionFactoryBeanName.
  */
 protected String getSessionFactoryBeanName() {
  return sessionFactoryBeanName;
 }


 /**
  * @param sessionFactoryBeanName The sessionFactoryBeanName to set.
  */
 public void setSessionFactoryBeanName(String sessionFactoryBeanName) {
  this.sessionFactoryBeanName = sessionFactoryBeanName;
 }


 protected SessionFactory lookupSessionFactory() {
  if (logger.isDebugEnabled()) {
   logger.debug("Using SessionFactory '" + getSessionFactoryBeanName() + "'
for OpenSessionInViewFilter");
  }
  WebApplicationContext wac =
    WebApplicationContextUtils.getRequiredWebApplicationContext(getServletContext());
  return (SessionFactory) wac.getBean(getSessionFactoryBeanName(),
SessionFactory.class);
 }

 protected void doFilterInternal(
   HttpServletRequest request, HttpServletResponse response, FilterChain
filterChain)
   throws ServletException, IOException {
  SessionFactory sessionFactory = lookupSessionFactory();
  HttpSession httpSession = request.getSession();
  Session session =
   (Session) httpSession.getAttribute(SESSION_KEY);
  if (session == null) {
   session = sessionFactory.openSession();
   httpSession.setAttribute(SESSION_KEY, session);
  }
                if (!session.isConnected()) {
                    session.reconnect();
                }
  TransactionSynchronizationManager.bindResource(sessionFactory, new
SessionHolder(session));
  try {
   filterChain.doFilter(request, response);
  } finally {
   TransactionSynchronizationManager.unbindResource(sessionFactory);
                        session.disconnect();
  }

 }

}