一、mybatisPlus实现自定义方法

1、创建映射文件

2、自定义方法

/**
     * 根据map集合id查询用户
     * @param id
     * @return
     */
     Map<String ,Object> selectMapId(Long id);

3、UserMapper.xml

<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE mapper
        PUBLIC "-//mybatis.org//DTD mapper 3.0//EN"
        "http://mybatis.org/dtd/mybatis-3-mapper.dtd">
<mapper namespace="com.cjc.mybatisplus.mapper.UserMapper">
<!--selectMapId-->
<select id="selectMapId" resultType="map">
    select id,name,age,email from user where id = #{id}
</select>
</mapper>

4、测试方法

 /**
     * 测试自定义接口
     */
    @Test
    public void selectUserMapId(){
        Map<String, Object> userMap = userMapper.selectMapId(3L);
        System.out.println("userMap=" + userMap);
    }