springboot的Web项目编译运行时提示错误：Field userService in com.cetc.UserManger.controller.UserController required a bean of type 'com.cetc.UserManger.service.UserService' that could not be found.

错误描述：

　　springboot的Web项目编译运行时提示错误：Field userService in com.cetc.UserManger.controller.UserController required a bean of type 'com.cetc.UserManger.service.UserService' that could not be found.

解决办法：

　　在提示错误的service的实现类impl上添加注解@Service。如下代码所示：

UserRepository的代码如下：

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

UserService的代码如下：

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

UserServiceImpl的代码如下：

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

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

UserController的代码如下：

@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的索引是从0开始的，size的索引是从1开始的
        return userService.findAll(request);
    }
}