Jakarta Struts Cookbook

10.4. Integrating Struts with Hibernate

Problem

You want to use Hibernate for object/relational mapping in your Struts application.

Solution

Use a servlet filter such as the Persistence class shown in Example 10-11.

Example 10-11. Servlet filter for Hibernate sessions

package com.jadecove.util; import java.io.*; import javax.servlet.*; import net.sf.hibernate.*; import net.sf.hibernate.cfg.Configuration; /** * Filter which manages a ThreadLocal hibernate session. Obtain the session * by calling Persistance.getSession( ). */ public class Persistence implements Filter { /** * Holds the current hibernate session, if one has been created. */ protected static ThreadLocal hibernateHolder = new ThreadLocal( ); protected static SessionFactory factory; public void init(FilterConfig filterConfig) throws ServletException { // Initialize hibernate try { doInit( ); } catch (HibernateException ex) { throw new ServletException(ex); } } /** * This method should only be called when this class is used directly - * that is, when using this class outside of the servlet container. * @throws HibernateException */ public static void doInit( ) throws HibernateException { factory = new Configuration( ).configure( ).buildSessionFactory( ); } public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain) throws IOException, ServletException { if (hibernateHolder.get( ) != null) throw new IllegalStateException( "A session is already associated with this thread! " + "Someone must have ...