1.导包

<dependency>
			<groupId>org.mybatis.spring.boot</groupId>
			<artifactId>mybatis-spring-boot-starter</artifactId>
			<version>1.1.1</version>
		</dependency>
		<dependency>
			<groupId>mysql</groupId>
			<artifactId>mysql-connector-java</artifactId>
			<version>5.1.21</version>
		</dependency>

 2.配置文件配置

spring.datasource.url=jdbc:mysql://127.0.0.1:3306/db
spring.datasource.username=root
spring.datasource.password=123
spring.datasource.driver-class-name=com.mysql.jdbc.Driver

3.mapper文件

public interface UserMapper {
    @Select("select * from user ")
    List<User> queryAll();

    @Insert("insert into user (id,username,password) values(null,#{username},#{password})")
    int insert(@Param("username") String username,@Param("password") String password);

}

4.service文件

@Service
public class UserService {
    @Autowired
    private UserMapper userMapper;

    public int insert(User user){
        return userMapper.insert(user.getUsername(),user.getPassword());
    }

    public List<User> queryAlls(){
        return userMapper.queryAll();
    }

5.controller文件

@RestController
public class User1Controller {
    @Autowired
    private UserService userService;

    @RequestMapping("/qu")
    public List<User> queryAlls(){
        return userService.queryUser();
    }

    @RequestMapping("/in")
    public int insert(@RequestBody User user){
        return userService.insert(user);
    }
}

6.启动类

@EnableAutoConfiguration
@ComponentScan(basePackages = {"com.syf.study.controller","com.syf.study.service"})
@MapperScan(basePackages = {"com.syf.study.mapper"})
@SpringBootApplication
public class SpringbootagainApplication {

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