0
点赞
收藏
分享

微信扫一扫

SpringBoot系列之集成MybatisPlus操作指南

1、什么是mybatisPlus?

​​MyBatis-Plus ​​,引用官网的说法:

MyBatis-Plus (opens new window)(简称 MP)是一个 MyBatis (opens new window)的增强工具,在 MyBatis 的基础上只做增强不做改变,为简化开发、提高效率而生。

2、创建MybatisPlus项目

开发环境

  • JDK 1.8
  • SpringBoot2.2.1
  • Maven 3.2+
  • Mysql5.7.36
  • 开发工具
  • IntelliJ IDEA
  • smartGit

使用阿里的脚手架,链接:​​https://start.aliyun.com​​

SpringBoot系列之集成MybatisPlus操作指南_spring boot
选择mybatis plus framework
SpringBoot系列之集成MybatisPlus操作指南_spring boot_02
新建application.yml,加上配置:

mybatis-plus:
type-aliases-package: com.example.mybatisplus.*.*.model
mapper-locations: classpath*:mapper/*/*.xml
configuration:
map-underscore-to-camel-case: true
default-statement-timeout: 60

创建数据库表,sql使用官网的

DROP TABLE IF EXISTS user;

CREATE TABLE user
(
id BIGINT(20) NOT NULL COMMENT '主键ID',
name VARCHAR(30) NULL DEFAULT NULL COMMENT '姓名',
age INT(11) NULL DEFAULT NULL COMMENT '年龄',
email VARCHAR(50) NULL DEFAULT NULL COMMENT '邮箱',
PRIMARY KEY (id)
);

表数据,数据使用官网的

DELETE FROM user;

INSERT INTO user (id, name, age, email) VALUES
(1, 'Jone', 18, 'test1@baomidou.com'),
(2, 'Jack', 20, 'test2@baomidou.com'),
(3, 'Tom', 28, 'test3@baomidou.com'),
(4, 'Sandy', 21, 'test4@baomidou.com'),
(5, 'Billie', 24, 'test5@baomidou.com');

3、MybatisPlus快速入门

写一个例子,写一套RestFul风格的curd接口:

加上注解​​@TableName​​​,id加上​​@TableId​

package com.example.mybatisplus.model;

import com.baomidou.mybatisplus.annotation.TableId;
import com.baomidou.mybatisplus.annotation.TableName;
import lombok.AllArgsConstructor;
import lombok.Data;
import lombok.NoArgsConstructor;
import lombok.ToString;
import lombok.experimental.SuperBuilder;

import java.io.Serializable;

@TableName("user")
@Data
@SuperBuilder(toBuilder = true)
@AllArgsConstructor
@NoArgsConstructor
@ToString
public class User implements Serializable {
@TableId
private Long id;
private String name;
private Integer age;
private String email;

}

加上一个mapper类,继承​​BaseMapper​

package com.example.mybatisplus.mapper;

import com.baomidou.mybatisplus.core.mapper.BaseMapper;
import com.example.mybatisplus.model.User;

public interface UserMapper extends BaseMapper<User>{

}

​MapperScan​​​扫描具体的mapper包,就不需要每个mapper类都加​​@Mapper​

package com.example.mybatisplus;

import org.mybatis.spring.annotation.MapperScan;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.boot.autoconfigure.jdbc.DataSourceAutoConfiguration;

@SpringBootApplication
@MapperScan("com.example.mybatisplus.mapper")
public class SpringbootMybatisPlusApplication {

public static void main(String[] args) {
SpringApplication.run(SpringbootMybatisPlusApplication.class, args);
}
}

接口实现​​IService​

package com.example.mybatisplus.service;
import com.baomidou.mybatisplus.extension.service.IService;
import com.example.mybatisplus.model.User;
public interface IUserService extends IService<User> {

}

接口实现类实现​​ServiceImpl​

package com.example.mybatisplus.service.impl;
import com.baomidou.mybatisplus.extension.service.impl.ServiceImpl;
import com.example.mybatisplus.mapper.UserMapper;
import com.example.mybatisplus.model.User;
import com.example.mybatisplus.service.IUserService;
import org.springframework.stereotype.Service;
@Service
public class UserServiceImpl extends ServiceImpl<UserMapper , User> implements IUserService {

}

写一个RestFul风格的控制类:

package com.example.mybatisplus.controller;

import cn.hutool.core.bean.BeanUtil;
import com.example.mybatisplus.common.ResultBean;
import com.example.mybatisplus.model.User;
import com.example.mybatisplus.model.dto.UserDto;
import com.example.mybatisplus.model.vo.UserVo;
import com.example.mybatisplus.service.impl.UserServiceImpl;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.*;

import java.util.List;

@RestController
@RequestMapping(value = "/api")
public class UserController {

@Autowired
private UserServiceImpl userService;

@GetMapping(value = {"/user"})
public ResultBean<List<UserVo>> users() {
List<User> poList = userService.list();
List<UserVo> voList = BeanUtil.copyToList(poList , UserVo.class);
return ResultBean.ok(voList);
}

@GetMapping(value = {"/user/{id}"})
public ResultBean<UserVo> user(@PathVariable("id")Integer id) {
User user = userService.getById(id);
UserVo userVo = BeanUtil.copyProperties(user , UserVo.class);
return ResultBean.ok(userVo);
}

@PostMapping(value = "/user")
public ResultBean<User> save(@RequestBody UserDto userDto) {
User user = BeanUtil.copyProperties(userDto , User.class);
boolean flag = userService.save(user);
if (flag) return ResultBean.ok(user);
return ResultBean.badRequest("新增失败");
}

@DeleteMapping(value = "/user/{id}")
public ResultBean<Integer> del(@PathVariable("id") Integer id) {
boolean flag = userService.removeById(id);
if (flag) return ResultBean.ok(id);
return ResultBean.badRequest("删除失败");
}

@PutMapping(value = "/user")
public ResultBean<User> update(@RequestBody UserDto userDto) {
User user = BeanUtil.copyProperties(userDto , User.class);
boolean flag = userService.updateById(user);
if (flag) return ResultBean.ok(user);
return ResultBean.badRequest("更新失败");
}

}

封装一个ResultBean类:

package com.example.mybatisplus.common;

import lombok.Data;
import org.springframework.http.HttpStatus;

/**
* <pre>
* ResultBean
* </pre>
*
* <pre>
* @author mazq
* 修改记录
* 修改后版本: 修改人: 修改日期: 2020/08/10 17:07 修改内容:
* </pre>
*/
@Data
public class ResultBean<T> {

/**
* 状态
* */
private int status;
/**
* 描述
* */
private String desc;
/**
* 数据返回
* */
private T data;

public ResultBean(int status, String desc, T data) {
this.status = status;
this.desc = desc;
this.data = data;
}

public ResultBean(T data) {
this.status = HttpStatus.OK.value();
this.desc = "处理成功";
this.data = data;
}

public static <T> ResultBean<T> ok(T data) {
return new ResultBean(data);
}

public static <T> ResultBean<T> ok() {
return new ResultBean(null);
}

public static <T> ResultBean<T> badRequest(String desc,T data) {
return new ResultBean(HttpStatus.BAD_REQUEST.value(), desc, data);
}

public static <T> ResultBean<T> badRequest(String desc) {
return new ResultBean(HttpStatus.BAD_REQUEST.value(), desc, null);
}

public static <T> ResultBean serverError(String desc, T data){
return new ResultBean(HttpStatus.INTERNAL_SERVER_ERROR.value(),"服务器内部异常:"+desc,data);
}

public static <T> ResultBean serverError(String desc){
return new ResultBean(HttpStatus.INTERNAL_SERVER_ERROR.value(),"服务器内部异常:"+desc,null);
}

}
<dependency>
<groupId>com.baomidou</groupId>
<artifactId>dynamic-datasource-spring-boot-starter</artifactId>
<version>3.4.1</version>
</dependency>

4、多数据源配置

pom加上配置:

<dependency>
<groupId>com.baomidou</groupId>
<artifactId>mybatis-plus-boot-starter-test</artifactId>
<version>3.4.3.4</version>
</dependency>

多数据源,参考​​官网​​

spring:
datasource:
dynamic:
primary: shop #设置默认的数据源或者数据源组,默认值即为master
strict: false #严格匹配数据源,默认false. true未匹配到指定数据源时抛异常,false使用默认数据源
datasource:
shop:
url: jdbc:mysql://127.0.0.1:3306/shop?useUnicode=true&characterEncoding=utf-8
username: root
password:
driver-class-name: com.mysql.jdbc.Driver # 3.2.0开始支持SPI可省略此配置
schema: classpath:db/schema-mysql.sql
data: classpath:db/data-mysql.sql
slave_1:
url: jdbc:mysql://127.0.0.1:3306/canaltest?useUnicode=true&characterEncoding=utf-8
username: root
password:
driver-class-name: com.mysql.jdbc.Driver

表格来自​​官网​​​:
SpringBoot系列之集成MybatisPlus操作指南_sql_03

package com.example.mybatisplus.mapper;

import com.baomidou.dynamic.datasource.annotation.DS;
import com.baomidou.mybatisplus.core.mapper.BaseMapper;
import com.example.mybatisplus.model.User;

@DS(value = "shop")
public interface UserMapper extends BaseMapper<User>{

}

有些版本可能可能会出现异常:Failed to configure a DataSource: ‘url‘ attribute is not specified and no embedded datasource

这种情况,可以排查数据源的自动配置

@SpringBootApplication(exclude= {DataSourceAutoConfiguration.class})

5、MybatisPlus测试

pom配置:

<dependency>
<groupId>com.baomidou</groupId>
<artifactId>mybatis-plus-boot-starter-test</artifactId>
<version>3.4.3.4</version>
</dependency>

测试类:

package com.example.mybatisplus;

import com.baomidou.mybatisplus.core.conditions.query.QueryWrapper;
import com.baomidou.mybatisplus.test.autoconfigure.MybatisPlusTest;
import com.example.mybatisplus.mapper.UserMapper;
import com.example.mybatisplus.model.User;
import org.junit.jupiter.api.Test;
import org.springframework.beans.factory.annotation.Autowired;

import java.util.List;

@MybatisPlusTest
class MybatisPlusSampleTest {

@Autowired
private UserMapper userMapper;

@Test
void test() {
List<User> userList = userMapper.selectList(new QueryWrapper<User>());
userList.stream().forEach(System.out::println);
}
}

6、和Lambda表达式的妙用

mybatisPlus支持Lambda表示式,单表查询的业务一遍用不上,还是给下具体的业务场景:列举电商spu和sku的例子,spu表和sku表有一张关联表,传入一个spuCode,查询对应的spu清单,具体sql

SELECT
*
FROM
t_sku sku
LEFT JOIN t_spu_sku_relate r ON sku.skuCode = r.skuCode
WHERE
r.spuCode = #{spuCode};

先查出关联表数据,然后再查具体的业务表,可以使用​​LambdaQueryWrapper​​表达式

String spucode = "123456";
final List<SkuBean> list = new ArrayList<SkuBean>();
relationMapper.selectList(new LambdaQueryWrapper<SkuSpuRelationBean>()
.eq(SkuSpuRelationBean::getSpuCode, spuCode)).forEach(
relation ->
list.add(
skuMapper.selectById(relation.getSkuCode()))
);

再给一个例子,使用了in,然后再嵌套一条sql的:

SELECT
*
FROM
t_sku sku
WHERE
sku.skuCode IN (
SELECT
skuCode form t_spu_sku_relate
WHERE
spu_code = '123456');

使用​​LambdaQueryWrapper​​​加上​​inSql​​来实现:

LambdaQueryWrapper<SkuBean> queryWrapper = new LambdaQueryWrapper<SkuBean>();
queryWrapper.inSql(SkuBean::getSkuCode,
"SELECT SKU_CODE FROM T_SKU_SPU_RELATE WHERE SPU_CODE = '123456'");
List<SkuBean> skus = skuDao.selectList(queryWrapper);

本博客代码例子,可以在github找到​​下载链接​​

博客参考资料

MybatisPlus官方文档:​​https://baomidou.com/pages/24112f/​​


举报

相关推荐

0 条评论