如何从url下载文件并将文件保存在flutter中的资源文件夹中？

import 'dart:io';
import 'package:dio/dio.dart';
import 'package:path_provider/path_provider.dart';

Future<void> downloadFile(String url, String fileName) async {
  Dio dio = Dio();
  try {
    Directory appDocDir = await getApplicationDocumentsDirectory();
    String appDocPath = appDocDir.path;
    String filePath = '$appDocPath/$fileName';

    await dio.download(url, filePath);
    print('File downloaded to: $filePath');
  } catch (e) {
    print('Error downloading file: $e');
  }
}

void main() {
  String fileUrl = 'https://example.com/file.pdf';
  String fileName = 'file.pdf';
  downloadFile(fileUrl, fileName);
}