在Spring中使用泛型生成服务

public interface GenericService<T> {
    void save(T entity);
    T findById(Long id);
    List<T> findAll();
}

@Service
public class GenericServiceImpl<T> implements GenericService<T> {
    @Autowired
    private GenericRepository<T> repository;

    @Override
    public void save(T entity) {
        repository.save(entity);
    }

    @Override
    public T findById(Long id) {
        return repository.findById(id);
    }

    @Override
    public List<T> findAll() {
        return repository.findAll();
    }
}

@RestController
public class UserController {
    @Autowired
    private GenericService<User> userService;

    @PostMapping("/users")
    public void createUser(@RequestBody User user) {
        userService.save(user);
    }

    @GetMapping("/users/{id}")
    public User getUserById(@PathVariable Long id) {
        return userService.findById(id);
    }

    @GetMapping("/users")
    public List<User> getAllUsers() {
        return userService.findAll();
    }
}