版本

• springboot 2.7.16
• druid 1.1.22
• mybatis-plus-boot-starter 3.4.2
• mysql 5.7.38

当然别的版本应该也差不多，最多改改相关类

步骤

1、搭建一个简单的springboot项目，版本选择2.7.16

参考从官网开始用IDEA在JDK1.8环境搭建springboot2.7.14项目

2、引入druid，mybatis-plus的相关依赖

        <!--数据库配置-->
        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
            <version>8.0.25</version>
        </dependency>
        <!--数据源-->
        <dependency>
            <groupId>com.alibaba</groupId>
            <artifactId>druid</artifactId>
            <version>1.1.22</version>
        </dependency>
        <!--自动化配置-->
        <dependency>
            <groupId>com.alibaba</groupId>
            <artifactId>druid-spring-boot-starter</artifactId>
            <version>1.1.22</version>
        </dependency>
        <!--mybatis-plus -->
        <dependency>
            <groupId>com.baomidou</groupId>
            <artifactId>mybatis-plus-boot-starter</artifactId>
            <version>3.4.2</version>
        </dependency>

3、配置文件引入数据源

spring:
  datasource:
    driver-class-name: com.mysql.cj.jdbc.Driver
    url: jdbc:mysql://localhost:3306/demo?serverTimezone=Asia/Shanghai
    username: root
    password: 123456
    type: com.alibaba.druid.pool.DruidDataSource #Druid类型

4、建库建表插入数据

CREATE DATABASE demo;
CREATE TABLE user(
     userid BIGINT  not null primary key COMMENT '主键ID,雪花算法生成',
    username VARCHAR(64) COMMENT '用户名称：这里用微信的昵称'
);
INSERT INTO `demo`.`user` (`userid`, `username`) VALUES (1, '小林');
INSERT INTO `demo`.`user` (`userid`, `username`) VALUES (2, '小马');

5、建User.class

package com.example.demo;
public class User {
    private String userid;
    private String username;
    public String getUserid() {
        return userid;
    }
    public void setUserid(String userid) {
        this.userid = userid;
    }
    public String getUsername() {
        return username;
    }
    public void setUsername(String username) {
        this.username = username;
    }
    @Override
    public String toString() {
        return "User{" +
                "userid='" + userid + '\'' +
                ", username='" + username + '\'' +
                '}';
    }
}

6、建UserMapper.class

package com.example.demo;
import com.baomidou.mybatisplus.core.mapper.BaseMapper;
import org.springframework.stereotype.Repository;
@Repository
public interface UserMapper extends BaseMapper<User> {
}

7、在DemoController加上测试逻辑

package com.example.demo;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RestController;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
@RestController
public class DemoController {
    @Autowired
    UserMapper userMapper;
    @GetMapping("/find")
    public List<User> Test1(){
        return userMapper.selectList(null);
    }
    @GetMapping("/hello")
    public Map<String,Object> hello(){
        Map<String,Object> result = new HashMap<String,Object>();
        result.put("hello","Hello World");
        return result;
    }
}

8、启动类加上注解@MapperScan

package com.example.demo;
import org.mybatis.spring.annotation.MapperScan;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
@SpringBootApplication
@MapperScan("com.example.demo")
public class DemoApplication {
    public static void main(String[] args) {
        SpringApplication.run(DemoApplication.class, args);
    }
}

9、启动访问http://localhost:8080/find

结果返回

[
    {
        "userid": "1",
        "username": "小林"
    },
    {
        "userid": "2",
        "username": "小马"
    }
]

10、项目结构简单粗暴

搞定！