Hibernate常用方法之_查询

1、使用session的get方法

     public User getUser(int id){
         Session session = null;
         User user = null;
         try {
             session = HibernateUtils.getSession();
             /*根据主键获取一条记录*/
             user = (User) session.get(User.class,id);
         }finally {
             if (session != null){
                 session.close();
             }
         }
         return user;
     }

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2、使用HQL语言查询 Query

     public User getUserBynName(String name){
         User user = null;
         Session session = null;
         try {
             session = HibernateUtils.getSession();
             /*这里查的是User对象，不是user表，支持多态*/
             String hql = " FROM User as user WHERE user.name = :name ";
             Query query = session.createQuery(hql);
             query.setString("name",name);
             /*只返回一条记录，否则报错*/
             user = (User) query.uniqueResult();
         }finally {
             if (session != null){
                 session.close();
             }
         }
         return user;
     }

     public List<User> getUsersByName(String name){
         List<User> users = null;
         Session session = null;
         try {
             session = HibernateUtils.getSession();
             /*这里查的是User对象，不是user表，支持多态*/
             String hql = " FROM User as user WHERE user.name LIKE :name ";
             Query query = session.createQuery(hql);
             query.setString("name",name+"%");
             query.setFirstResult(10);
             query.setMaxResults(5);
             users = query.list();
         }finally {
             if (session != null){
                 session.close();
             }
         }
         return users;
     }

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3、使用条件查询 Criteria

     public User getUserByNameCri(String name){
         Session session = null;
         User user = null;
         try {
             session = HibernateUtils.getSession();
             /*条件查询*/
             Criteria criteria = session.createCriteria(User.class);
             /*添加约束条件*/
             criteria.add(Restrictions.eq("name",name));
             user = (User) criteria.uniqueResult();
         }finally {
             if (session != null){
                 session.close();
             }
         }
         return user;
     }