Java spring boot如何初始化存储库

我的服务级别如上图所示。为什么spring可以初始化接口？谢谢

Spring正在为接口创建代理，代理将所有调用委托给已经存在的实现。

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包含一个很好的解释

也许你可以在这里找到答案

@Repository
public interface RoomRepository extends CrudRepository<Room, Long>{
    Room findByNumber(String number);
}

@Service
public class ReservationService {
    private RoomRepository roomRepository;
    private GuestRepository guestRepository;
    private ReservationRepository reservationRepository;

    @Autowired
    public ReservationService(RoomRepository roomRepository, GuestRepository guestRepository, ReservationRepository reservationRepository) {
        this.roomRepository = roomRepository;
        this.guestRepository = guestRepository;
        this.reservationRepository = reservationRepository;
    }