MyBatis增删改查

https://blog.csdn.net/qq_45864838/article/details/120934495?spm=1001.2014.3001.5501

resultType:返回值类型，如果为实体类，则需要写具体位置，如com.he.pojo.User

parameterType为传入参数类型，通过#{ }可以获取。

#{ }可以直接填类的字段#{username}，#{pwd}等

也可以用map传参，#{ }填的是map的key值

int insertUser(User user);

        insert into mybatis.user(id, username, pwd) VALUES(#{id},#{username},#{pwd})
    

注意要手动提交事务，否则不会持久化进数据库！

 //增
    @Test
    public void insertUser(){
        SqlSession sqlSession = MyBatisUtils.getSqlSession();
        UserMapper mapper = sqlSession.getMapper(UserMapper.class);
        int res = mapper.insertUser(new User(4, "火狐", "123123"));

        if(res>0) System.out.println("插入成功");
        sqlSession.commit(); //增删改都是事务，需要手动提交！！！！

        sqlSession.close();
    }

与增类似，这里只附上配置映射，以及测试代码。

配置：

 
        delete from mybatis.user where id=#{id}
    

测试：

 //删
    @Test
    public void deleteUser(){
        SqlSession sqlSession = MyBatisUtils.getSqlSession();
        UserMapper mapper = sqlSession.getMapper(UserMapper.class);
        mapper.deleteUser(4);

        sqlSession.commit();

        sqlSession.close();
    }

配置：

        update mybatis.user set username=#{username},pwd=#{pwd} where id=#{id}
    

测试：

//改
    @Test
    public void updateUser(){
        SqlSession sqlSession = MyBatisUtils.getSqlSession();
        UserMapper mapper = sqlSession.getMapper(UserMapper.class);
        mapper.updateUser(new User(4,"呵呵","157762"));

        sqlSession.commit();
        sqlSession.close();
    }

配置：

        select * from mybatis.user where id=#{id}
     
测试：
 
//查
    @Test
    public void getUserById(){
        SqlSession sqlSession = MyBatisUtils.getSqlSession();
        UserMapper mapper = sqlSession.getMapper(UserMapper.class);

        User user = mapper.getUserById(1);
        System.out.println(user);

        sqlSession.close();
    }
 
模糊查询： 
配置：
 

        select * from mybatis.user where username like #{value}
    

测试：

//模糊查询
    @Test
    public void getUserByLastName(){
        SqlSession sqlSession = MyBatisUtils.getSqlSession();
        UserMapper mapper = sqlSession.getMapper(UserMapper.class);

        List userList = mapper.getUserByLastName("李%");
        for (User user : userList) {
            System.out.println(user);
        }

        sqlSession.commit();
        sqlSession.close();
    }

使用map传参，parameterType里填写map，#{ }里为key值。

配置：

//map的使用
    @Test
    public void updatePwd(){
        SqlSession sqlSession = MyBatisUtils.getSqlSession();
        UserMapper mapper = sqlSession.getMapper(UserMapper.class);
        HashMap map = new HashMap<>();
        map.put("id",1);
        map.put("pwd",987561);

        mapper.updatePwd(map);

        sqlSession.commit();
        sqlSession.close();
    }

        update mybatis.user set pwd=#{pwd} where id=#{id}
    

测试：

//map的使用
    @Test
    public void updatePwd(){
        SqlSession sqlSession = MyBatisUtils.getSqlSession();
        UserMapper mapper = sqlSession.getMapper(UserMapper.class);
        HashMap map = new HashMap<>();
        map.put("id",1);
        map.put("pwd",987561);

        mapper.updatePwd(map);

        sqlSession.commit();
        sqlSession.close();
    }

环境配置好后，只需要先在接口中添加方法，再在对应的配置文件中配置相应的语句，再在测试类中测试，

测试类模板：

@Test
    public void 函数名(){
        SqlSession sqlSession = MyBatisUtils.getSqlSession();
        UserMapper mapper = sqlSession.getMapper(接口.class);
       

        mapper.接口方法名()；

        sqlSession.commit();//手动提交
        sqlSession.close();//关闭连接
    }