Map by value

一、Map的使用说明

假设,我们的实体类,或者数据库中的表,字段或者参数过多,我们应当考虑使用Map！
使用Map时,则Entity classes are not required了！（It is recommended to use when there are too many fields or parameters！）

二、Map 实例

Jump to previous article：
https://blog.csdn.net/weixin_45737330/article/details/126064436

Just modify the following code！

使用Map添加信息

1、Mapper接口

 //使用mapto add user information
   int getUserAdd02(Map<String,Object> map);

2、XML

<insert id="getUserAdd02" parameterType="map">
        insert into mybatis01.user(id, name, pwd)
        values (#{Ku_Id},#{Ku_Name},#{Ku_Pwd});
</insert>

3、Test

@Test
    public void UserAdd(){
    
        SqlSession sqlSession = MybatisUtil.getSqlSession();
        UserMapper mapper = sqlSession.getMapper(UserMapper.class);

        //创建HashMap对象
        HashMap<String, Object> map = new HashMap<>();
        map.put("Ku_Id",6);
        map.put("Ku_Name","酷");
        map.put("Ku_Pwd","097");
        mapper.getUserAdd02(map);

        System.out.println(map);

        //增删改一定要提交事务 
        sqlSession.commit();
        sqlSession.close();
    }

使用Map删除信息

1、Mapper接口

 	//使用map来删除用户信息
    int getUserDel02(Map<String,Object> map);

2、XML

<delete id="getUserDel02" parameterType="map">
        delete
        from mybatis01.user
                 where id=#{Ku_Id};
    </delete>

3、Test

 @Test
    public void UserDelete(){
    
        SqlSession sqlSession = MybatisUtil.getSqlSession();
        UserMapper mapper = sqlSession.getMapper(UserMapper.class);

        HashMap<String, Object> map = new HashMap<>();
        map.put("Ku_Id",12);
        int i = mapper.getUserDel02(map);
        if(i>0){
    
            System.out.println("删除成功！");
        }else{
    
            System.out.println("删除失败");
        }
        System.out.println(map);
		//增删改一定要提交事务
        sqlSession.commit();
        sqlSession.close();
    }

使用Map修改信息

1、Mapper接口

	//使用map来修改用户信息
    int getUserUpdate02(Map<String,Object> map);

2、XML

 <update id="getUserUpdate02" parameterType="map">
        update mybatis01.user
            set  id=#{Ku_Id},name=#{Ku_Name},pwd=#{Ku_Pwd} 
        where id=#{Ku_Id};
    </update>

3、Test

 @Test
    public void UserUpd(){
    
        SqlSession sqlSession = MybatisUtil.getSqlSession();
        UserMapper mapper = sqlSession.getMapper(UserMapper.class);
        
        //创建HashMap对象
        HashMap<String, Object> map = new HashMap<>();
        map.put("Ku_Id",6);
        map.put("Ku_Name","亚");
        map.put("Ku_Pwd","3321");
        mapper.getUserUpdate02(map);
        System.out.println(map);
        //增删改一定要提交事务
        sqlSession.commit();
        sqlSession.close();
    }

使用Map查询信息

1、Mapper接口

    //使用map来查询用户信息
    List<Map> getUserSelect02(Map<String,Object> map);

2、XML

 	<select id="getUserSelect02" resultType="map">
        select *
        from mybatis01.user where id=#{kxy_Id};
    </select>

3、Test

	@Test
    public void getUserSelect02(){
    
        SqlSession sqlSession = MybatisUtil.getSqlSession();
        UserMapper mapper = sqlSession.getMapper(UserMapper.class);
        //创建HashMap对象
        HashMap<String, Object> map = new HashMap<>();
        map.put("kxy_Id",6);
        List<Map> mapList = mapper.getUserSelect02(map);
        for (Map map1 : mapList) {
    
            System.out.println(map1);
        }
		//增删改一定要提交事务 sqlSession.commit();
        sqlSession.close();
    }

总结

• Map传递参数,直接在sql中取出key即可！【parameterType=“map”】
• 对象传递参数,直接在sql中取对象的属性即可！【parameterType=“Object”】(int属性可省略不写！)
• 只有一个基本类型参数的情况下,可以直接在sql中取到！ 多个参数用Map,或者注解！