hibernate不同版本中sessionFactory获取方法

    Configuration cf = new Configuration().configure();    //configuration会自动读取src下的hibernate.cfg.xml文件，当此文件名改变时，设置修改的名称为形参。//      Configuration cf = new Configuration().configure("hib.cfg.xml");        //在hibernate3.x中是这种写法//      SessionFactory sf = cf.buildSessionFactory();        //在hibernate4.0-4.2为此写法        ServiceRegistry sr = new ServiceRegistryBuilder()                            .applySettings(cf.getProperties())                            .buildServiceRegistry()              //在hibernate4.3写法    //      ServiceRegistry sr = new StandardServiceRegistryBuilder()//                              .applySettings(cf.getProperties())//                              .build();    SessionFactory sf = cf.buildSessionFactory(sr);    Session session = sf.openSession();    //第一种    Transaction tra = session.beginTransaction();    //第二种：必须  ----开始事务//      Transaction tra = session.getTransaction();//      tra.begin();