mybatis注解使用报错是为什么

Question

为什么报错

public interface UserService {
    User getUser();
}

public class UserServiceImpl implements UserService {

    @Resource
    private UserMapper userMapper;

    public User getUser(){
        return userMapper.getUser();
    }
}

@Mapper
public interface UserMapper {
    User getUser();
}

 public static void main(String[] args) {
        SpringApplication.run(SkyApplication.class, args);
        UserService userService=new UserServiceImpl();
        System.out.println(userService.getUser());
        log.info("server started");
    }

报错信息：

Answer 1

UserMapper userMapper 没有注入成功