关于mybatis:Mybatis入门之CRUD

xml元素

• namespace
  xml中的namespace与dao接口的包名统一
• id
  xml中的id与dao接口的办法名统一
• resultType
  sql语句执行的返回值
• parameterType
  参数类型

select

1. 编写接口

//查问全副用户List<User> getUserList();

2. 编写sql语句

<!--select查问语句--><select id="getUserList" resultType="com.sunfl.pojo.User">    select * from mybatis.user</select>

3. 测试

@Testpublic void test(){    //取得SqlSession对象    SqlSession sqlSession = MybatisUtils.getSqlSession();    //形式一：执行SQL  举荐    UserMapper userMapper = sqlSession.getMapper(UserMapper.class);    List<User> userList = userMapper.getUserList();    //形式二：//        List<User> userList = sqlSession.selectList("com.sunfl.dao.UserDao.getUserList");    for (User user : userList) {        System.out.println(user);    }    //敞开sqlSession    sqlSession.close();}

insert

1. 编写接口

//新增一个用户int addUser(User user);

2. 编写sql语句

<insert id="addUser" parameterType="com.sunfl.pojo.User">    insert into mybatis.user (id, name, pwd) values (#{id},#{name},#{pwd});</insert>

3. 测试

@Testpublic void addUser(){    SqlSession sqlSession = MybatisUtils.getSqlSession();    UserMapper mapper = sqlSession.getMapper(UserMapper.class);    mapper.addUser(new User(4, "哈哈哈", "12323"));    sqlSession.commit();    sqlSession.close();}

update

1. 编写接口

//更新一个用户int updateUser(User user);

2. 编写sql语句

<update id="updateUser" parameterType="com.sunfl.pojo.User">    update mybatis.user set name=#{name},pwd=#{pwd} where id=#{id};</update>

3. 测试

@Testpublic void updateUser(){    SqlSession sqlSession = MybatisUtils.getSqlSession();    UserMapper mapper = sqlSession.getMapper(UserMapper.class);    mapper.updateUser(new User(4,"嘿嘿","1111"));    sqlSession.commit();    sqlSession.close();}

delete

1. 编写接口

//删除一个用户int deleteUser(int id);

2. 编写sql语句

<delete id="deleteUser" parameterType="int">    delete from mybatis.user where id = #{id};</delete>

3. 测试

@Testpublic void deleteUser(){    SqlSession sqlSession = MybatisUtils.getSqlSession();    UserMapper mapper = sqlSession.getMapper(UserMapper.class);    mapper.deleteUser(4);    sqlSession.commit();    sqlSession.close();}