Flutter HttpPost方式上传文件

final form = FormData({
      'expressno':packageNoController.text,
      'position':packagePositionController.text,
      'goodcount':packageNumController.text,
      'weight':packageWeightController.text,
      'account':accountController.text,
      'adminid':_storage.read('auth_info_userid'),
    });
    for (var e in files) {
      if(e == null || e.path == null){
        continue;
      }
      form.files.add(MapEntry<String,MultipartFile>('file',MultipartFile(e!.path, filename:e.name)));
    }

    final map = await provider.addPackage(form);

方式二(dio)

Future<Map> postFile(XFile file)async{
    var dio = diodio.Dio();
    var map = {
      'file' : await diodio.MultipartFile.fromFile(file.path,filename:file.name)
    };
    var formData = diodio.FormData.fromMap(map);
    final resp = await dio.post("$baseUrl/api/admin/Upload/PostFile",data:formData);
    return resp.data;
  }