hibernate的SessionFactory工具类

import org.hibernate.HibernateException;
import org.hibernate.Session;
import org.hibernate.cfg.Configuration;
import org.hibernate.service.ServiceRegistry;
import org.hibernate.service.ServiceRegistryBuilder;
public class HibernateSessionFactory {

	private static final ThreadLocal<Session> threadLocal = new ThreadLocal<Session>();
	private static org.hibernate.SessionFactory sessionFactory;
	private static Configuration configuration = new Configuration();
	private static ServiceRegistry serviceRegistry; 

	static {
    		try {
			configuration.configure();
			serviceRegistry = new ServiceRegistryBuilder().applySettings(configuration.getProperties()).buildServiceRegistry();
			sessionFactory = configuration.buildSessionFactory(serviceRegistry);
		} catch (Exception e) {
			System.err.println("%%%% Error Creating SessionFactory %%%%");
			e.printStackTrace();
		}
	}
	private HibernateSessionFactory() { }
	
	public static Session getSession() throws HibernateException {
        	Session session = (Session) threadLocal.get();

		if (session == null || !session.isOpen()) {
			if (sessionFactory == null) {
				rebuildSessionFactory();
			}
			session = (sessionFactory != null) ? sessionFactory.openSession() : null;
			threadLocal.set(session);
		}

        	return session;
	}

	public static void rebuildSessionFactory() {
		try {
			configuration.configure();
			serviceRegistry = new ServiceRegistryBuilder().applySettings(configuration.getProperties()).buildServiceRegistry();
			sessionFactory = configuration.buildSessionFactory(serviceRegistry);
		} catch (Exception e) {
			System.err.println("%%%% Error Creating SessionFactory %%%%");
			e.printStackTrace();
		}
	}

	public static void closeSession() throws HibernateException {
        	Session session = (Session) threadLocal.get();
        	threadLocal.set(null);

        	if (session != null) {
            		session.close();
        	}
    	}
	public static org.hibernate.SessionFactory getSessionFactory() {
		return sessionFactory;
	}

	public static Configuration getConfiguration() {
		return configuration;
	}
}