1、简介

1）、什么是MP？

MyBatis-Plus
为简化开发而生

• 润物无声
  只做增强不做改变，引入它不会对现有工程产生影响，如丝般顺滑。

• 效率至上
  只需简单配置，即可快速进行单表 CRUD 操作，从而节省大量时间。

• 丰富功能
  代码生成、物理分页、性能分析等功能一应俱全。

2）、官网

https://mybatis.plus/

2、SpringBoot集成

1）、添加依赖

        <dependency>
            <groupId>com.baomidou</groupId>
            <artifactId>mybatis-plus-boot-starter</artifactId>
            <version>3.1.2</version>
        </dependency>

2）、数据库配置

spring.application.name=server-mybatis-plus
server.port=8000

## Mybatis
spring.datasource.url=jdbc:mysql://localhost:3306/db_test?autoReconnect=true&useUnicode=true&characterEncoding=utf8&serverTimezone=Asia/Shanghai
spring.datasource.username=root
spring.datasource.password=root
mybatis.typeAliasesPackage=com.shenmazong.servermybatisplus.mapper
mybatis.mapperLocations=classpath:/mapper/*.xml
logging.level.com.shenmazong.servermybatisplus.mapper=debug

3）、数据库表

SET NAMES utf8mb4;
SET FOREIGN_KEY_CHECKS = 0;
-- ----------------------------
-- Table structure for tb_student
-- ----------------------------
DROP TABLE IF EXISTS `tb_student`;
CREATE TABLE `tb_student`  (
  `id` int(11) NOT NULL AUTO_INCREMENT COMMENT '学生ID',
  `student_name` varchar(255) CHARACTER SET utf8 COLLATE utf8_general_ci NULL DEFAULT NULL COMMENT '学生名字',
  `age` int(11) NULL DEFAULT 0 COMMENT '学生年龄',
  PRIMARY KEY (`id`) USING BTREE
) ENGINE = InnoDB AUTO_INCREMENT = 7 CHARACTER SET = utf8 COLLATE = utf8_general_ci ROW_FORMAT = Dynamic;
-- ----------------------------
-- Records of tb_student
-- ----------------------------
INSERT INTO `tb_student` VALUES (1, '吕布', 13);
INSERT INTO `tb_student` VALUES (2, '赵云', 23);
INSERT INTO `tb_student` VALUES (3, '典韦', 25);
INSERT INTO `tb_student` VALUES (4, '黄盖', 35);
INSERT INTO `tb_student` VALUES (5, '马超', 26);
INSERT INTO `tb_student` VALUES (6, '张飞', 33);
SET FOREIGN_KEY_CHECKS = 1;

4）、定义pojo

package com.shenmazong.servermybatisplus.pojo;

import com.baomidou.mybatisplus.annotation.IdType;
import com.baomidou.mybatisplus.annotation.TableId;
import com.baomidou.mybatisplus.annotation.TableName;
import lombok.Data;

@Data
@TableName(value = "tb_student")
public class TbStudent {

    @TableId(value = "id", type = IdType.AUTO)
    private Integer id;

    private String studentName;
    private Integer age;
}

5）、定义mapper

package com.shenmazong.servermybatisplus.mapper;

import com.baomidou.mybatisplus.core.mapper.BaseMapper;
import com.shenmazong.servermybatisplus.pojo.TbStudent;
import org.apache.ibatis.annotations.Mapper;

@Mapper
public interface TbStudentMapper extends BaseMapper<TbStudent> {

}

6）、定义controller

package com.shenmazong.servermybatisplus.controller;

import com.baomidou.mybatisplus.core.conditions.query.QueryWrapper;
import com.shenmazong.servermybatisplus.mapper.TbStudentMapper;
import com.shenmazong.servermybatisplus.pojo.TbStudent;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RequestParam;
import org.springframework.web.bind.annotation.RestController;

@RestController
public class IndexController {

    @Autowired
    TbStudentMapper tbStudentMapper;

    @GetMapping(value = "/getById")
    public Object getById(@RequestParam("id") Integer id) {
        return tbStudentMapper.selectById(id);
    }

    @GetMapping(value = "/getOneById")
    public Object getOneById(@RequestParam("id") Integer id) {
        return tbStudentMapper.selectOne(
                new QueryWrapper<TbStudent>().lambda().eq(TbStudent::getId, id)
        );
    }

    @GetMapping(value = "/getList")
    public Object getOneById() {
        return tbStudentMapper.selectList(null);
    }

    @GetMapping(value = "/addStudent")
    public Object addStudent(@RequestParam("name") String name,
                             @RequestParam("age") Integer age) {
        TbStudent tbStudent = new TbStudent();
        tbStudent.setStudentName(name);
        tbStudent.setAge(age);

        return tbStudentMapper.insert(tbStudent);
    }

    @GetMapping(value = "/setStudent")
    public Object setStudent(@RequestParam("id") Integer id,
                             @RequestParam("name") String name,
                             @RequestParam("age") Integer age) {
        TbStudent tbStudent = new TbStudent();
        tbStudent.setId(id);
        tbStudent.setStudentName(name);
        tbStudent.setAge(age);

        return tbStudentMapper.updateById(tbStudent);
    }

    @GetMapping(value = "/delStudent")
    public Object setStudent(@RequestParam("id") Integer id) {
        return tbStudentMapper.selectById(id);
    }
}

3、mapper使用xml

1）、定义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.shenmazong.servermybatisplus.mapper.TbStudentMapper">
    <select id="getOneById" resultType="com.shenmazong.servermybatisplus.pojo.TbStudent">
        select * from tb_student where id=#{id}
    </select>
</mapper>

2）、mapper定义

package com.shenmazong.servermybatisplus.mapper;

import com.baomidou.mybatisplus.core.mapper.BaseMapper;
import com.shenmazong.servermybatisplus.pojo.TbStudent;
import org.apache.ibatis.annotations.Mapper;
import org.apache.ibatis.annotations.Param;

@Mapper
public interface TbStudentMapper extends BaseMapper<TbStudent> {

    TbStudent getOneById(@Param("id") Integer id);

}

3）、编写controller

package com.shenmazong.servermybatisplus.controller;

import com.baomidou.mybatisplus.core.conditions.query.QueryWrapper;
import com.shenmazong.servermybatisplus.mapper.TbStudentMapper;
import com.shenmazong.servermybatisplus.pojo.TbStudent;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RequestParam;
import org.springframework.web.bind.annotation.RestController;

@RestController
public class IndexController {

    @Autowired
    TbStudentMapper tbStudentMapper;

    @GetMapping(value = "/getById")
    public Object getById(@RequestParam("id") Integer id) {
        return tbStudentMapper.selectById(id);
    }

    @GetMapping(value = "/getOneById")
    public Object getOneById(@RequestParam("id") Integer id) {
        return tbStudentMapper.selectOne(
                new QueryWrapper<TbStudent>().lambda().eq(TbStudent::getId, id)
        );
    }

    @GetMapping(value = "/getList")
    public Object getList() {
        return tbStudentMapper.selectList(null);
    }

    @GetMapping(value = "/addStudent")
    public Object addStudent(@RequestParam("name") String name,
                             @RequestParam("age") Integer age) {
        TbStudent tbStudent = new TbStudent();
        tbStudent.setStudentName(name);
        tbStudent.setAge(age);

        return tbStudentMapper.insert(tbStudent);
    }

    @GetMapping(value = "/setStudent")
    public Object setStudent(@RequestParam("id") Integer id,
                             @RequestParam("name") String name,
                             @RequestParam("age") Integer age) {
        TbStudent tbStudent = new TbStudent();
        tbStudent.setId(id);
        tbStudent.setStudentName(name);
        tbStudent.setAge(age);

        return tbStudentMapper.updateById(tbStudent);
    }

    @GetMapping(value = "/delStudent")
    public Object setStudent(@RequestParam("id") Integer id) {
        return tbStudentMapper.selectById(id);
    }

    @GetMapping(value = "/getOneByXml")
    public Object getOneByXml(@RequestParam("id") Integer id) {
        return tbStudentMapper.getOneById(id);
    }
}