Java tutorial
/* * Copyright 2005 Joe Walker * * 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.directwebremoting.hibernate; import java.lang.reflect.Method; import javax.servlet.ServletContext; import org.apache.commons.logging.LogFactory; import org.apache.commons.logging.Log; import org.directwebremoting.AjaxFilter; import org.directwebremoting.AjaxFilterChain; import org.directwebremoting.WebContextFactory; import org.hibernate.Session; import org.hibernate.SessionFactory; import org.hibernate.Transaction; /** * An {@link AjaxFilter} that uses DWR Hibernate support classes to do a * {@link Session#beginTransaction()} before passing the control on to the chain * and a {@link Transaction#commit()} after. * @author Joe Walker [joe at getahead dot ltd dot uk] */ public class H3SessionAjaxFilter implements AjaxFilter { /* (non-Javadoc) * @see org.directwebremoting.AjaxFilter#doFilter(java.lang.Object, java.lang.reflect.Method, java.lang.Object[], org.directwebremoting.AjaxFilterChain) */ public Object doFilter(Object object, Method method, Object[] params, AjaxFilterChain chain) throws Exception { ServletContext context = WebContextFactory.get().getServletContext(); SessionFactory sessionFactory = (SessionFactory) context.getAttribute(ATTRIBUTE_SESSION); Transaction transaction = null; if (sessionFactory != null) { Session session = sessionFactory.getCurrentSession(); transaction = session.beginTransaction(); } else { log.error( "SessionFactory not initialized for this web application. Use: H3SessionAjaxFilter.setSessionFactory(servletContext, sessionFactory);"); } Object reply = chain.doFilter(object, method, params); if (transaction != null) { transaction.commit(); } return reply; } /** * Assigns a {@link SessionFactory} to a {@link ServletContext} so DWR knows * how to get hold of a {@link org.hibernate.Session}. * @param context The Servlet environment to store the ServletContext in * @param sessionFactory The Hibernate session factory to register */ public static void setSessionFactory(ServletContext context, SessionFactory sessionFactory) { context.setAttribute(ATTRIBUTE_SESSION, sessionFactory); } /** * Get access to a Session, given the {@link SessionFactory} linked in * {@link #setSessionFactory(ServletContext, SessionFactory)} * @param context The webapp to link the calls together * @return A Session from the {@link SessionFactory} or null if * {@link #setSessionFactory(ServletContext, SessionFactory)} has not been * called for this {@link ServletContext} */ public static Session getCurrentSession(ServletContext context) { SessionFactory sessionFactory = (SessionFactory) context.getAttribute(ATTRIBUTE_SESSION); if (sessionFactory == null) { return null; } return sessionFactory.getCurrentSession(); } /** * The log stream */ private static final Log log = LogFactory.getLog(H3SessionAjaxFilter.class); /** * Under what name do we store the session factory? */ protected static final String ATTRIBUTE_SESSION = "org.directwebremoting.hibernate.SessionFactory"; }