hibernatesessionfactory.java

基于myeclipse环境开发的一个包含hibernate实现持久层

package de.laliluna.library;

import net.sf.hibernate.HibernateException;
import net.sf.hibernate.Session;
import net.sf.hibernate.cfg.Configuration;

/**
 * Configures and provides access to Hibernate sessions, tied to the current
 * thread of execution. Follows the Thread Local Session pattern, see
 * {@link http://hibernate.org/42.html}.
 */
public class HibernateSessionFactory {

	/**
	 * Location of hibernate.cfg.xml file. NOTICE: Location should be on the
	 * classpath as Hibernate uses #resourceAsStream style lookup for its
	 * configuration file. That is place the config file in a Java package - the
	 * default location is the default Java package.<br>
	 * <br>
	 * Examples: <br>
	 * <code>CONFIG_FILE_LOCATION = "/hibernate.conf.xml". 
	 * CONFIG_FILE_LOCATION = "/com/foo/bar/myhiberstuff.conf.xml".</code>
	 */
	private static String CONFIG_FILE_LOCATION = "/hibernate.cfg.xml";

	/** Holds a single instance of Session */
	private static final ThreadLocal threadLocal = new ThreadLocal();

	/** The single instance of hibernate configuration */
	private static final Configuration cfg = new Configuration();

	/** The single instance of hibernate SessionFactory */
	private static net.sf.hibernate.SessionFactory sessionFactory;

	/**
	 * Returns the ThreadLocal Session instance. Lazy initialize the
	 * <code>SessionFactory</code> if needed.
	 * 
	 * @return Session
	 * @throws HibernateException
	 */
	public static Session currentSession() throws HibernateException {
		Session session = (Session) threadLocal.get();
		/*
		 * 牋牋 * [laliluna] 20.12.2004 牋牋 * we want to use the standard
		 * session.close() method and not the closeSession() from this class. 牋牋 *
		 * For this we need the following line of code. 牋牋
		 */
		if (session != null && !session.isOpen())
			session = null;
		if (session == null)
		{
			if (sessionFactory == null)
			{
				try
				{
					cfg.configure(CONFIG_FILE_LOCATION);
					sessionFactory = cfg.buildSessionFactory();
				} catch (Exception e)
				{
					System.err.println("%%%% Error Creating SessionFactory %%%%");
					e.printStackTrace();
				}
			}
			session = sessionFactory.openSession();
			threadLocal.set(session);
		}

		return session;
	}

	/**
	 * Close the single hibernate session instance.
	 * 
	 * @throws HibernateException
	 */
	public static void closeSession() throws HibernateException {
		Session session = (Session) threadLocal.get();
		threadLocal.set(null);

		if (session != null)
		{
			session.close();
		}
	}

	/**
	 * Default constructor.
	 */
	private HibernateSessionFactory() {
	}

}