de.berlios.jedi.data.HibernateUtil.java Source code

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Here is the source code for de.berlios.jedi.data.HibernateUtil.java

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/*
 * Copyright 2005-2006 Daniel Calvio Snchez
 * 
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License
 * as published by the Free Software Foundation; either version 2
 * of the License, or (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY.
 *
 * See the COPYING file for more details.
 */

package de.berlios.jedi.data;

import org.apache.commons.logging.LogFactory;
import org.hibernate.*;
import org.hibernate.cfg.*;

import de.berlios.jedi.common.config.ConfigurationFactory;

/**
 * <p>
 * Helper class for using Hibernate.<br>
 * Allows getting a session instance for Thread (and closing it when it is not
 * longer needed).
 * </p>
 * 
 * <p>
 * This class was got from Hibernate Reference Documentation,
 * http://www.hibernate.org/hib_docs/v3/reference/en/html/index.html<br>
 * Only minor changes were made.
 * </p>
 */
public class HibernateUtil {

    /**
     * A thread local variable for Hibernate sessions.
     */
    public static final ThreadLocal session = new ThreadLocal();

    /**
     * Factory for session creating.
     */
    private static final SessionFactory sessionFactory;

    static {
        try {
            // Create the SessionFactory
            sessionFactory = new Configuration()
                    .configure(ConfigurationFactory.getConfiguration().getString("path.hibernateConfigFile"))
                    .buildSessionFactory();
        } catch (Throwable ex) {
            LogFactory.getLog(HibernateUtil.class).error("Initial SessionFactory creation failed.", ex);
            throw new ExceptionInInitializerError(ex);
        }
    }

    /**
     * Returns a new session if this Thread has none yet, or the same session
     * requested before.
     * 
     * @return An Hibernate session.
     * 
     * @throws HibernateException
     *             If there was a problem opening the Hibernate session.
     */
    public static Session currentSession() throws HibernateException {
        Session s = (Session) session.get();
        // Open a new Session, if this Thread has none yet
        if (s == null) {
            s = sessionFactory.openSession();
            session.set(s);
        }
        return s;
    }

    /**
     * Closes the active session.<br>
     * If there was no active session for this Thread, nothing is done.
     */
    public static void closeSession() {
        Session s = (Session) session.get();
        if (s != null) {
            try {
                s.close();
            } catch (HibernateException e) {
                LogFactory.getLog(HibernateUtil.class).error("An error occured when closing the Hibernate session",
                        e);
            }
        }
        session.set(null);
    }
}