1.创建springboot项目

    <dependencies>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>
         <!--   mybatis-plus maven坐标依赖     -->
        <dependency>
            <groupId>com.baomidou</groupId>
            <artifactId>mybatis-plus-boot-starter</artifactId>
            <version>3.4.1</version>
        </dependency>
         <!--  mysql数据库驱动-->
        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
            <scope>runtime</scope>
        </dependency>
        <dependency>
            <groupId>org.projectlombok</groupId>
            <artifactId>lombok</artifactId>
            <optional>true</optional>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-test</artifactId>
            <scope>test</scope>
        </dependency>
    </dependencies>

2.yml 注意数据库名’springboot_test’

spring:
  datasource:
    driver-class-name: com.mysql.cj.jdbc.Driver
    url: jdbc:mysql://localhost:3306/springboot_test?allowMultiQueries=true&useUnicode=true&characterEncoding=UTF-8&useSSL=false&serverTimezone=GMT%2B8
    username: root
    password: root
server:
  port: 9527

3结构

sys_user.sql 文件

CREATE TABLE `sys_user` (
  `id` bigint NOT NULL,
  `username` varchar(255) COLLATE utf8mb4_general_ci DEFAULT NULL,
  `password` varchar(255) COLLATE utf8mb4_general_ci DEFAULT NULL,
  `email` varchar(255) COLLATE utf8mb4_general_ci DEFAULT NULL,
  `address` varchar(255) COLLATE utf8mb4_general_ci DEFAULT NULL,
  `create_id` bigint DEFAULT NULL,
  `create_time` datetime DEFAULT NULL,
  `update_id` bigint DEFAULT NULL,
  `update_time` datetime DEFAULT NULL,
  PRIMARY KEY (`id`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_general_ci;

INSERT INTO `springboot_test`.`sys_user`(`id`, `username`, `password`, `email`, `address`, `create_id`, `create_time`, `update_id`, `update_time`) VALUES (1, 'mei', 'xxxxx', '90xxxx@', '北京市', NULL, NULL, NULL, NULL);

SysUser.java

package cn.lanca.vo;

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

import java.util.Date;

@Data
@TableName("sys_user")
public class SysUser {
    //id
    @TableId
    private Long id;
    private String username;
    private String password;
    private String email;
    private String address;
    private Long createId;
    private Date createTime;
    private Long updateId;
    private Date updateTime;
}

SysUserMapper 注意@Mapper将其扫描进去交给spring容器管理

package cn.lanca.mapper;

import cn.lanca.vo.SysUser;
import com.baomidou.mybatisplus.core.mapper.BaseMapper;
import org.apache.ibatis.annotations.Mapper;

@Mapper
public interface SysUserMapper extends BaseMapper<SysUser> {

}

ISysUserService

package cn.lanca.service;

import cn.lanca.vo.SysUser;
import com.baomidou.mybatisplus.extension.service.IService;

public interface ISysUserService extends IService<SysUser> {
}

SysUserServiceImpl 注意添加@Service

package cn.lanca.service.impl;

import cn.lanca.mapper.SysUserMapper;
import cn.lanca.service.ISysUserService;
import cn.lanca.vo.SysUser;
import com.baomidou.mybatisplus.extension.service.impl.ServiceImpl;
import org.springframework.stereotype.Service;

@Service
public class SysUserServiceImpl extends ServiceImpl<SysUserMapper, SysUser> implements ISysUserService {
}

4测试

package cn.lanca;

import cn.lanca.mapper.SysUserMapper;
import cn.lanca.vo.SysUser;
import org.junit.jupiter.api.Test;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.test.context.SpringBootTest;

import java.util.List;

@SpringBootTest
class SpringbootMybatisApplicationTests {

    @Autowired
    private SysUserMapper sysUserMapper;

    @Test
    void contextLoads() {
        List<SysUser> sysUsers = sysUserMapper.selectList(null);
        sysUsers.forEach(System.out::println);
    }
}

5.打印结果

2022-04-01 21:30:41.799  INFO 1324 --- [           main] com.zaxxer.hikari.HikariDataSource       : HikariPool-1 - Starting...
2022-04-01 21:30:42.070  INFO 1324 --- [           main] com.zaxxer.hikari.HikariDataSource       : HikariPool-1 - Start completed.
SysUser(id=1, username=mei, password=xxx, email=90xxx@, address=北京市, createId=null, createTime=null, updateId=null, updateTime=null)