package com.wj.app.util;

 import org.hibernate.Session;

 import org.hibernate.SessionFactory;

 import org.hibernate.cfg.Configuration;

 import org.hibernate.service.ServiceRegistry;

 import org.hibernate.service.ServiceRegistryBuilder;

 public class HibernateUtil {

     public static final SessionFactory sessionFactory;

     //ThreadLocal可以隔离多个线程的数据共享，因此不需要对线程进行同步

     public static ThreadLocal<Session> session = new ThreadLocal<Session>();

     static

     {

         //使用默认配置文件创建Configuration实例

         Configuration cfg = new Configuration()

                                  .configure();

         //以Configuration实例来创建SessionFactory实例

         ServiceRegistry serviceRegistry = new ServiceRegistryBuilder()

                                                .applySettings(cfg.getProperties())

                                                .buildServiceRegistry();

         /*ServiceRegistry serviceRegistry = new StandardServiceRegistryBuilder()

         .applySettings(cfg.getProperties()).build();*/

         sessionFactory = cfg.buildSessionFactory(serviceRegistry);

     }

     public static Session currentSession() {

         Session s = session.get();

         //如果该线程还没有Session，则创建一个新的Session

         if (s == null)

         {

             s = sessionFactory.openSession();

             //将获得的Session变量存储在ThreadLocal变量session里

             session.set(s);

         }

         return s;

     }

     public static void clossSession() {

         Session s = session.get();

         if (s != null)

         {

             s.close();

         }

         session.set(null);

     }

 }