Hibernate 对象生命周期及crud操作

publicvoid testSave(){

      Session session=null;

      Transaction tx=null;

      User user=null;

      try {

         session = HibernateUtil.getSession();

         tx = session.beginTransaction();

         //构造对象--瞬时状态

         user = new User();

         user.setName("刘德华");

         user.setPwd("2222");

         //持久状态，user被session管理，并且id有值--oid

         session.save(user);

         //在持久状态下；脏数据检查：当提交事务，清理缓存时发现session中数据

         //和数据库中数据不一致时，将会把session中的数据更新到数据库中

         user.setName("学友");

         //在保存以后再修改对象那么将会产生2条sql语句，那么效率较低，建议在save前修改

         session.flush();

         txmit();

      } catch (Exception e) {

         e.printStackTrace();

         tx.rollback();

      }finally{

         HibernateUtil.closeSession();

      }

      //user:游离状态

      System.out.println("姓名："&#Name());

      user.setName("朝伟");

      try {

         session = HibernateUtil.getSession();

         tx = session.beginTransaction();

         //持久状态

         session.update(user);

         txmit();

      } catch (Exception e) {

         e.printStackTrace();

         tx.rollback();

      }finally{

         HibernateUtil.closeSession();

      }

   }

@Test

   publicvoid testLoad(){

      Session session=null;

      Transaction tx=null;

      User user=null;

      try {

         session = HibernateUtil.getSession();

         tx = session.beginTransaction();

         //持久状态

         //load方法相当于之前的getById

         //如果load查询的数据不存在，那么抛出异常

         //load不会立即查询数据，当使用的时候再查找数据

         user = (User)session.load(User.class,1) ;

         //System.out.println(user);

         System.out.println("姓名："&#Name());

         txmit();

      } catch (Exception e) {

         e.printStackTrace();

         tx.rollback();

      }finally{

         HibernateUtil.closeSession();

      }

   }

   @Test

   publicvoid testGet(){

      Session session=null;

      Transaction tx=null;

      User user=null;

      try {

         session = HibernateUtil.getSession();

         tx = session.beginTransaction();

         //持久状态

         //get方法相当于之前的getById

         //如果get查询的数据不存在，那么返回null

         //get方法会立即查询数据(session--数据库)

         user = ((User.class, 1) ;

         System.out.println(user);

         user.setName("张三");

         //System.out.println("姓名："&#Name());

         txmit();

      } catch (Exception e) {

         e.printStackTrace();

         tx.rollback();

      }finally{

         //关闭session

         HibernateUtil.closeSession();

      }

      //游离状态

      user.setName("siggy");

      System.out.println("============");

      try {

         session = HibernateUtil.getSession();

         tx = session.beginTransaction();

         //持久

         session.update(user);

         txmit();

      } catch (Exception e) {

         e.printStackTrace();

         tx.rollback();

      }finally{

         //关闭session

         HibernateUtil.closeSession();

      }

   }

   @Test

   publicvoid testGet1(){

      Session session=null;

      Transaction tx=null;

      User user=null;

      try {

         session = HibernateUtil.getSession();

         tx = session.beginTransaction();

         //持久状态

         //get方法相当于之前的getById

         //如果get查询的数据不存在，那么返回null

         //get方法会立即查询数据(session--数据库)

         user = ((User.class, 2) ;

         session.delete(user);

         //瞬时状态

         user.setName("王五");

         txmit();

      } catch (Exception e) {

         e.printStackTrace();

         tx.rollback();

      }finally{

         //关闭session

         HibernateUtil.closeSession();

      }

      //瞬时状态

   }

@Test

   publicvoid testUpdate(){

      Session session=null;

      Transaction tx=null;

      User user=null;

      try {

         session = HibernateUtil.getSession();

         tx = session.beginTransaction();

         //手动创建对象可以被更新，需要指定id

         //当指定id不存在时会抛异常

         user = new User();

         user.setId(10);

         user.setName("paul");

         session.update(user);

         txmit();

      } catch (Exception e) {

         e.printStackTrace();

         tx.rollback();

      }finally{

         //关闭session

         HibernateUtil.closeSession();

      }

      //瞬时状态

   }

   @Test

   publicvoid testUpdate1(){

      Session session=null;

      Transaction tx=null;

      User user=null;

      try {

         session = HibernateUtil.getSession();

         tx = session.beginTransaction();

         //手动创建对象可以被更新，需要指定id

         //当指定id不存在时会抛异常

         user = ((User.class, 1);

         user.setName("t_bag");

         user.setPwd("3333");

         session.update(user);

         txmit();

      } catch (Exception e) {

         e.printStackTrace();

         tx.rollback();

      }finally{

         //关闭session

         HibernateUtil.closeSession();

      }

      //瞬时状态

   }

@Test

   publicvoid testDelete(){

      Session session=null;

      Transaction tx=null;

      User user=null;

      try {

         session = HibernateUtil.getSession();

         tx = session.beginTransaction();

         //手动构建对象并指定id可以从数据库删除

         //如果指定id不存在将抛异常

         user = new User();

         user.setId(3);

         session.delete(user);

         txmit();

      } catch (Exception e) {

         e.printStackTrace();

         tx.rollback();

      }finally{

         //关闭session

         HibernateUtil.closeSession();

      }

      //瞬时状态

   }

   @Test

   publicvoid testDelete1(){

      Session session=null;

      Transaction tx=null;

      User user=null;

      try {

         session = HibernateUtil.getSession();

         tx = session.beginTransaction();

         user = ((User.class, 1);

         if(user!=null)

            session.delete(user);

         txmit();

      } catch (Exception e) {

         e.printStackTrace();

         tx.rollback();

      }finally{

         //关闭session

         HibernateUtil.closeSession();

      }

      //瞬时状态

   }