springboot的Web項目編譯運行時提示錯誤：Field userService in com.cetc.UserManger.controller.UserController required a bean of type 'com.cetc.UserManger.service.UserService' that could not be found.

錯誤描述：

　　springboot的Web項目編譯運行時提示錯誤：Field userService in com.cetc.UserManger.controller.UserController required a bean of type 'com.cetc.UserManger.service.UserService' that could not be found.

解決辦法：

　　在提示錯誤的service的實現類impl上添加注解@Service。如下代碼所示：

UserRepository的代碼如下：

public interface UserRepository extends JpaRepository<User,Integer> {
}

UserService的代碼如下：

public interface UserService {
    public Page<User> findAll(Pageable pageable);
}

UserServiceImpl的代碼如下：

@Service
public class UserServiceImpl implements UserService {
    @Autowired
    private UserRepository userRepository;

    @Override
    public Page<User> findAll(Pageable pageable){
        return userRepository.findAll(pageable);
    }
}

UserController的代碼如下：

@RestController
@RequestMapping("/user")
public class UserController {
    @Autowired
    private UserService userService;

    @GetMapping("/findAll/{page}/{size}")
    public Page<User> findAll(@PathVariable("page") Integer page, @PathVariable("size") Integer size){
        PageRequest request=PageRequest.of(page,size);//注意：page的索引是從0開始的，size的索引是從1開始的
        return userService.findAll(request);
    }
}