de.nava.informa.impl.hibernate.SessionHandler.java Source code

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Here is the source code for de.nava.informa.impl.hibernate.SessionHandler.java

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//
// Informa -- RSS Library for Java
// Copyright (c) 2002, 2003 by Niko Schmuck
//
// Niko Schmuck
// http://sourceforge.net/projects/informa
// mailto:niko_schmuck@users.sourceforge.net
//
// This library is free software.
//
// You may redistribute it and/or modify it under the terms of the GNU
// Lesser General Public License as published by the Free Software Foundation.
//
// Version 2.1 of the license should be included with this distribution in
// the file LICENSE. If the license is not included with this distribution,
// you may find a copy at the FSF web site at 'www.gnu.org' or 'www.fsf.org',
// or you may write to the Free Software Foundation, 675 Mass Ave, Cambridge,
// MA 02139 USA.
//
// This library is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied waranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
// Lesser General Public License for more details.
//

// $Id: SessionHandler.java,v 1.17 2005/09/24 22:35:15 niko_schmuck Exp $

package de.nava.informa.impl.hibernate;

import java.sql.Connection;
import java.util.Properties;

import org.hibernate.HibernateException;
import org.hibernate.Session;
import org.hibernate.SessionFactory;
import org.hibernate.cfg.Configuration;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;

/**
 * Singleton class from which hibernate sesssions may be retrieved needed
 * for transactions.
 *
 * @author Niko Schmuck
 */
public class SessionHandler {

    private static Log logger = LogFactory.getLog(SessionHandler.class);

    private static SessionHandler myInstance;

    private SessionFactory sessFactory;
    private Connection conn;
    private Session curSession;

    /**
     * Constructor which configures hibernate, in this order:
     * <ol>
     * <li>Reads hibernate.cfg.xml or hibernate.properties file from the
     * CLASSPATH to retrieve information about how the database can be
     * accessed (JDBC connection properties).</li>
     * <li>Then reads in the definiton files for all related informa hibernate
     * classes (*.hbm.xml)</li>
     * <li>Finally, if supplied, applies a Properties object to do a final
     * override.</li>
     * </ol>
     *
     * @throws HibernateException In case a problem occurred while configuring
     *                            hibernate or creating the session factory.
     */
    private SessionHandler(Properties props) throws HibernateException {
        // reads in hibernate.properties implictly for database connection settings
        Configuration cfg = new Configuration();

        // attempt to use standard config file named hibernate.cfg.xml
        try {
            cfg.configure();
        } catch (HibernateException he) {
            logger.info("Can't find \"hibernate.cfg.xml\" in classpath.");
        }

        // add base classes
        cfg.addClass(Channel.class).addClass(Item.class).addClass(ItemGuid.class).addClass(ItemEnclosure.class)
                .addClass(ItemSource.class).addClass(Cloud.class).addClass(Category.class)
                .addClass(ChannelGroup.class).addClass(ChannelSubscription.class).addClass(Image.class)
                .addClass(ItemMetadata.class).addClass(TextInput.class);

        // If Properties were supplied then use them as the final override
        if (props != null)
            cfg.addProperties(props);

        // get session factory (expensive)
        sessFactory = cfg.buildSessionFactory();
    }

    /**
     * Returns the one and only instance which can be used to obtain a
     * {@link Session} for further operation with the hibernate objects.
     *
     * @throws HibernateException In case a problem occurred while configuring
     *                            hibernate or creating the session factory.
     */
    public static synchronized SessionHandler getInstance(Properties props) throws HibernateException {

        if (myInstance == null)
            myInstance = new SessionHandler(props);
        return myInstance;
    }

    /**
     * Returns the singelton instance, calling
     * {@link #getInstance(Properties)} with properties set to null.
     */
    public static SessionHandler getInstance() throws HibernateException {
        return getInstance(null);
    }

    /**
     * Gets hibernate session object, if JDBC <code>Connection</code> was
     * set earlier this will be used for the opening a hibernate session.
     */
    public Session getSession() throws HibernateException {
        if (conn != null)
            curSession = sessFactory.openSession(conn);
        else
            curSession = sessFactory.openSession();
        return curSession;
    }

    /**
     * Gets a a new session whilst using an existing JDBC connection.
     *
     * @param conn JDBC connection
     */
    public Session getSession(Connection conn) {
        this.conn = conn;
        curSession = sessFactory.openSession(conn);
        return curSession;
    }

    /**
     * Gets the default JDBC Connection object.
     */
    public Connection getConnection() {
        return conn;
    }

    /**
     * Sets the default JDBC Connection object.
     */
    public void setConnection(Connection connection) {
        conn = connection;
    }

    /**
     * Returns true if session is open.
     */
    public boolean isSessionOpen() {
        return curSession.isOpen();
    }

}