新建SpringBoot项目

配置pom.xml

<dependency>
    <groupId>com.baomidou</groupId>
    <artifactId>mybatis-plus-boot-starter</artifactId>
    <version>3.4.3.1</version>
</dependency>
<dependency>
    <groupId>mysql</groupId>
    <artifactId>mysql-connector-java</artifactId>
    <version>8.0.20</version>
</dependency>

在 Spring Boot 启动类中添加 @MapperScan 注解，扫描 Mapper 文件夹

@SpringBootApplication
@MapperScan("mybatis.plus.test.mapper")
public class MybatisplustestApplication {
    public static void main(String[] args) {
        SpringApplication.run(MybatisplustestApplication.class, args);
    }
}

编写实体类bean.User

表结构根据 baomidou.com/guide/quick-start.html 设计

@Data
public class User {
    private Long id;
    private String name;
    private Integer age;
    private String email;
}

配置application.yml

spring:
  datasource:
    driver-class-name: com.mysql.cj.jdbc.Driver # 如果是MySQL5.x则用com.mysql.jdbc.Driver，否则报错
    url: jdbc:mysql://ip:port/database_name?useUnicode=true&characterEncoding=utf8&serverTimezone=Asia/Shanghai&useSSL=false
    username: username
    password: password

编写Mapper类 mapper.UserMapper

public interface UserMapper extends BaseMapper<User> {
}

添加测试类，进行功能测试

@Autowired
private UserMapper userMapper;
@Test
public void testSelect() {
    List<User> userList = userMapper.selectList(null);
    System.out.print(userList);
}