JTATransactionManagerFilter.java

/*
 * JBoss, Home of Professional Open Source.
 * Copyright 2012, Red Hat, Inc., and individual contributors
 * as indicated by the @author tags. See the copyright.txt file in the
 * distribution for a full listing of individual contributors.
 *
 * This is free software; you can redistribute it and/or modify it
 * under the terms of the GNU Lesser General Public License as
 * published by the Free Software Foundation; either version 2.1 of
 * the License, or (at your option) any later version.
 *
 * This software is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with this software; if not, write to the Free
 * Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA
 * 02110-1301 USA, or see the FSF site: http://www.fsf.org.
 */

package org.picketbox.quickstarts.filter;

import java.io.IOException;

import javax.annotation.Resource;
import javax.persistence.EntityManager;
import javax.persistence.PersistenceContext;
import javax.servlet.Filter;
import javax.servlet.FilterChain;
import javax.servlet.FilterConfig;
import javax.servlet.ServletException;
import javax.servlet.ServletRequest;
import javax.servlet.ServletResponse;
import javax.transaction.UserTransaction;

import org.picketbox.core.identity.jpa.EntityManagerPropagationContext;

/**
 * <p>
 * Simple {@link Filter} that intercepts all requests to make the {@link EntityManager} available to PicketBox by using the
 * {@link JPAIdentityStoreContext}. This is necessary to make the {@link EntityManager} available to the JPA-based Identity Store
 * </p>
 * <p>
 * It also begins a transaction at the beginning and the end of the request processing.
 * </p>
 * 
 * @author <a href="mailto:psilva@redhat.com">Pedro Silva</a>
 */
public class JTATransactionManagerFilter implements Filter {

    @PersistenceContext
    private EntityManager entityManager;

    @Resource
    private UserTransaction userTransaction;

    /* (non-Javadoc)
     * @see javax.servlet.Filter#init(javax.servlet.FilterConfig)
     */
    @Override
    public void init(FilterConfig filterConfig) throws ServletException {

    }

    /* (non-Javadoc)
     * @see javax.servlet.Filter#doFilter(javax.servlet.ServletRequest, javax.servlet.ServletResponse, javax.servlet.FilterChain)
     */
    @Override
    public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain) throws IOException,
            ServletException {
        // uses the EntityManagerContext to make the EntityManager available to the JPA Identity Store.
        EntityManagerPropagationContext.set(this.entityManager);

        try {
            this.userTransaction.begin();

            chain.doFilter(request, response);

            this.entityManager.flush();
            this.userTransaction.commit();
        } catch (Exception e) {
            try {
                this.userTransaction.rollback();
            } catch (Exception e1) {
                throw new RuntimeException("Error rolling back transaction.", e);
            }
        } finally {
            // clear the context.
            EntityManagerPropagationContext.clear();
        }
    }

    /* (non-Javadoc)
     * @see javax.servlet.Filter#destroy()
     */
    @Override
    public void destroy() {

    }

}