如何在flutter中将文件上传或保存到服务器？

import 'package:dio/dio.dart';
import 'package:file_picker/file_picker.dart';

void uploadFile() async {
  FilePickerResult result = await FilePicker.platform.pickFiles();

  if (result != null) {
    String fileName = result.files.single.name;
    String filePath = result.files.single.path;
    FormData formData = FormData.fromMap({
      "file": await MultipartFile.fromFile(filePath, filename: fileName),
    });

    try {
      Response response = await Dio().post("YOUR_UPLOAD_URL", data: formData);
      print(response.data);
    } catch (e) {
      print(e);
    }
  }
}