一、导入依赖

        <dependency>
            <groupId>org.mybatis.spring.boot</groupId>
            <artifactId>mybatis-spring-boot-starter</artifactId>
            <version>3.0.0</version>
        </dependency>
        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
            <version>8.0.29</version>
        </dependency>

二、编写配置文件

server:
  port: 8081
  servlet:
    context-path: /springboot1
spring:
  datasource:
    driver-class-name: com.mysql.cj.jdbc.Driver
    url: jdbc:mysql://127.0.0.1:3306/test1?useSSL=false&useUnicode=true&characterEncoding=UTF-8&serverTimezone=Asia/Shanghai
    username: root
    password: 123456
mybatis:
#  mapper映射文件包扫描
  mapper-locations: classpath:/mappers/*.xml
#  实体类别名包扫描
  type-aliases-package: com.buba.pojo

三、在启动类上添加注解，表示mapper接口所在位置

如果不在MyApplication启动类上添加@MapperScan必须在UserMapper接口上添加@Mapper注解。

@SpringBootApplication
//@MapperScan("com.buba.mappers")
public class ApplicationStarter {
  public static void main(String[] args) {
      SpringApplication.run(ApplicationStarter.class,args);
  }
}

四、定义mapper接口

package com.buba.mappers;
import org.apache.ibatis.annotations.Mapper;
import java.util.List;

/**
 * @author qlx
 */
@Mapper
public interface TestMapper {
    List<String> selectNameAll();
}

五、定义mapper.xml映射文件

在resource下新建mappers文件夹，mapper.xml文件名没有要求了，不需要和接口名完全对应了，是根据namespace去找接口。但是最好还是和接口名字保持一致

<?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.buba.mappers.TestMapper">
    <select id="selectNameAll" resultType="string">
        select name from user
    </select>
</mapper>

六、service层

@Service
public class TestServiceImpl implements TestService {
    @Autowired
    private TestMapper testMapper;
    @Override
    public List<String> selectNameAll() {
        return testMapper.selectNameAll();
    }
}

七、controller层

@RestController
@RequestMapping("/test")
public class TestController {
    
    @Autowired
    private TestService testService;

    @GetMapping("/selectNameAll")
    public List<String> selectNameAll() {
        return testService.selectNameAll();
    }
}