嗨，我有接受POST请求的控制器。
请求正文可以为空，也可以正文包含空字段：即或{ }

@RestController
public class UserController {
    @Autowired
    private UserService UserService;
    @RequestMapping(value = "/tree", method = POST,consumes = MediaType.APPLICATION_JSON_VALUE)
    public List<ResponseUser> controller(@RequestBody(required=false) UserDataRequest request) {
        return UserService.send(request);
    }
}

我的服务定义如下：
1.检查主体是否为空，即null
1.逐个检查字段是否为空
1.如果字段为空，则再次执行步骤1

@Service
public class UserService {

    @Autowired
    private RestTemplate restTemplate;

    private ResponseEntity<List<ResponseUser>> responseEntity;

    public List<ResponseUser> send(UserDataRequest data){

        //empty body == null
    if(data == null ) {
           // return list1 of type ResponseUser
        }
    else{

       //Check for the fields are present are not
        Optional<String> id = Optional.ofNullable(data.getid());
        Optional<String> search = Optional.ofNullable(data.getsearch());

        //if id is present 
        if (id.isPresent()) {
            // return list2 of type ResponseUser

        }

        //if search is present 
        else if(search.isPresent()){
        // return list3 of type ResponseUser

            }

        else {
        // return list1 of type ResponseUser
        }
    }
    return responseEntity.getBody();
    }
}

我想知道怎样才能不重复同样的事情？有什么有效的方法吗？