hibernate管理session的例子

package com.sict.employeeManagement.help;

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

public class HibernateUtil {

    public static SessionFactory getSessionFactory() {
        return _instance._sessionFactory;
    }
public static void closeSession(Session session) {
try {
if ((session != null) && (session.isOpen())) {
session.close();
}
}
catch (HibernateException he) {
he.printStackTrace();
}
}
public static Session openSession() throws HibernateException {
return openSession(getSessionFactory());
}

public static Session openSession(SessionFactory sessionFactory)
throws HibernateException {

return _instance._sessionFactory.getCurrentSession();
}
private HibernateUtil() {
        try {
Configuration configuration = new Configuration();
configuration = configuration.configure();
_sessionFactory = configuration.buildSessionFactory();
        }
catch (Exception e) {
e.printStackTrace();
        }
}
private static HibernateUtil _instance = new HibernateUtil();
private SessionFactory _sessionFactory;
}