hibernate的session详解

一 opensession与getCurrentSession的区别

1、 getCurrentSession在事务提交或者回滚之后会自动关闭，而openSession需要手动关闭。如果使用openSession而没有手动关闭，多次之后会导致连接池溢出。

2、openSession每次创建新的session对象，getCurrentSession使用现有的session对象。

 

二 测试openSession每次创建新的session对象

1、测试代码

        @Test

        public void testOpenSession(){

            // 创建配置对象  

            Configuration config = new Configuration().configure();

            // 创建服务注册对象

            ServiceRegistry serviceRegistery = new ServiceRegistryBuilder().applySettings(config.getProperties()).buildServiceRegistry();

            // 创建会话工厂对象

            SessionFactory sessionFactory = config.buildSessionFactory(serviceRegistery);

            // 创建会话对象

            Session session1 = sessionFactory.openSession();

            Session session2 = sessionFactory.openSession();

            System.out.println(session1==session2);                        

        }

2、运行结果

false

 

三 测试getCurrentSession使用现有的session对象

1、测试代码

        @Test

        public void testGetCurrentSession(){

            // 创建配置对象  

            Configuration config = new Configuration().configure();

            // 创建服务注册对象

            ServiceRegistry serviceRegistery = new ServiceRegistryBuilder().applySettings(config.getProperties()).buildServiceRegistry();

            // 创建会话工厂对象

            SessionFactory sessionFactory = config.buildSessionFactory(serviceRegistery);

            // 创建会话对象

            Session session1 = sessionFactory.getCurrentSession();

            Session session2 = sessionFactory.getCurrentSession();

            System.out.println(session1==session2);

        }

2、运行结果

true

 

四 openSession用完后必须手动关闭，否则会溢出

1、测试代码

       @Test

        public void testSaveStudentswithOpenSession(){

            // 创建配置对象  

            Configuration config = new Configuration().configure();

            // 创建服务注册对象

            ServiceRegistry serviceRegistery = new ServiceRegistryBuilder().applySettings(config.getProperties()).buildServiceRegistry();

            // 创建会话工厂对象

            SessionFactory sessionFactory = config.buildSessionFactory(serviceRegistery);

            // 创建会话对象

            Session session1 = sessionFactory.openSession();

            // 开启事务

            Transaction transaction = session1.beginTransaction();

                Students s= new Students(1,"张三丰","男",new Date(),"武当山");

                session1.doWork(new Work(){

 

                        @Override

                        public void execute(Connection connection) throws SQLException {

                                // TODO Auto-generated method stub

                                System.out.println("connection hashCode:"+connection.hashCode());

                        }

                });

                session1.save(s);

                //session.close();

                transaction.commit();

                

                Session session2 = sessionFactory.openSession();

                transaction = session2.beginTransaction();

                s= new Students(2,"李四","男",new Date(),"武当山");

                session2.doWork(new Work(){

 

                        @Override

                        public void execute(Connection connection) throws SQLException {

                                // TODO Auto-generated method stub

                                System.out.println("connection hashCode:"+connection.hashCode());

                        }

                });

                session2.save(s);

                transaction.commit();

        }

2、测试结果

connection hashCode:1048278180

Hibernate:

    insert

    into

        STUDENTS

        (SNAME, GENDER, BIRTHDAY, ADDRESS, SID)

    values

        (?, ?, ?, ?, ?)

connection hashCode:156943829

Hibernate:

    insert

    into

        STUDENTS

        (SNAME, GENDER, BIRTHDAY, ADDRESS, SID)

    values

        (?, ?, ?, ?, ?)

 

五 getCurrentSession不用关闭session

1、测试代码

        @Test

        public void testSaveStudentswithGetCurrentSession(){

                 // 创建配置对象  

            Configuration config = new Configuration().configure();

            // 创建服务注册对象

            ServiceRegistry serviceRegistery = new ServiceRegistryBuilder().applySettings(config.getProperties()).buildServiceRegistry();

            // 创建会话工厂对象

            SessionFactory sessionFactory = config.buildSessionFactory(serviceRegistery);

            // 创建会话对象

            Session session1 = sessionFactory.getCurrentSession();

            // 开启事务

            Transaction transaction = session1.beginTransaction();

                Students s= new Students(1,"张三丰","男",new Date(),"武当山");

                session1.doWork(new Work(){

                        @Override

                        public void execute(Connection connection) throws SQLException {

                                // TODO Auto-generated method stub

                                System.out.println("connection hashCode:"+connection.hashCode());

                        }

                });

                session1.save(s);

                transaction.commit();

                

                Session session2 = sessionFactory.getCurrentSession();

                transaction = session2.beginTransaction();

                s= new Students(2,"李四","男",new Date(),"武当山");

                session2.doWork(new Work(){

 

                        @Override

                        public void execute(Connection connection) throws SQLException {

                                // TODO Auto-generated method stub

                                System.out.println("connection hashCode:"+connection.hashCode());

                        }

                });

                session2.save(s);

                transaction.commit();

        }

2、运行结果

connection hashCode:455886737

Hibernate:

    insert

    into

        STUDENTS

        (SNAME, GENDER, BIRTHDAY, ADDRESS, SID)

    values

        (?, ?, ?, ?, ?)

connection hashCode:455886737

Hibernate:

    insert

    into

        STUDENTS

        (SNAME, GENDER, BIRTHDAY, ADDRESS, SID)

    values

        (?, ?, ?, ?, ?)