如何获取使用 Flutter 保存文件的 Android 下载路径？

Question

How to get the visible Android Downloads path for saving files using Flutter? Is this possibly because I am running the app in debug mode from android-studio device manager to a physically connected tablet as opposed to an installed app?

My Flutter app downloads files of any type from an API and I want to save them in the Downloads folder. This may seem like a simple question but I can't find the file anywhere on my android tablet.

This code returns /data/user/0/com.myapp/app_flutter/fatsquid.jpg

path_provider: ^2.0.11
import 'package:path_provider/path_provider.dart';
---
Future<String> getFilePath(uniqueFileName) async {
  String path = '';
  Directory dir = await getApplicationDocumentsDirectory();
  path = '${dir.path}/$uniqueFileName';
  return path;
}

My intention is to save the file in a visible directory, preferable the Downloads folder. I don't need the user to pick a directory, similar to web browsers.

I am using dio.download to return the file like this

  Future<void> downloadMobileFile(User user) async {
    log('downloading with mobile function ');
    setState(
      () {
        downloading = true;
        filename = user.downloadFileName;
      },
    );

    bool hasPermission = await _requestWritePermission();
    if (!hasPermission) return;

    String savePath = await getFilePath(user.downloadFileName);

    print(savePath);

    final storage = FlutterSecureStorage();

    String? token = await storage.read(key: 'jwt');

    Dio dio = Dio();

    dio.interceptors.add(LogInterceptor(responseBody: false));

    dio.download(
      user.fileUrl,
      savePath,
      options: Options(
        headers: {HttpHeaders.authorizationHeader: 'Bearer $token'},
      ),
      onReceiveProgress: (rcv, total) {
        setState(
          () {
            received =
                'received: ${rcv.toStringAsFixed(0)} out of total: ${total.toStringAsFixed(0)}';
            progress = ((rcv / total) * 100).toStringAsFixed(0);
          },
        );
        if (progress == '100') {
          setState(
            () {
              isDownloaded = true;
            },
          );
        } else if (double.parse(progress) < 100) {}
      },
      deleteOnError: true,
    ).then(
      (_) {
        print(progress);
        print(isDownloaded);

        setState(
          () {
            if (progress == '100') {
              isDownloaded = true;
            }
            downloading = false;
          },
        );
      },
    );
    // opens the file
    //OpenFile.open("${dir.path}/$fileName", type: 'application/pdf');
  }

  Future<bool> _requestWritePermission() async {
    await Permission.storage.request();
    return await Permission.storage.request().isGranted;
  }

console output from the download function:

[log] downloading with mobile function 
I/flutter (12774): file download path
I/flutter (12774): /data/user/0/com.mydomain/app_flutter/fatsquid.jpg
I/flutter (12774): *** Request ***
I/flutter (12774): uri: https://api.mydomain.com/transcript/download/transcript/file/1
I/flutter (12774): method: GET
I/flutter (12774): responseType: ResponseType.stream
I/flutter (12774): followRedirects: true
I/flutter (12774): connectTimeout: 0
I/flutter (12774): sendTimeout: 0
I/flutter (12774): receiveTimeout: 0
I/flutter (12774): receiveDataWhenStatusError: true
I/flutter (12774): extra: {}
I/flutter (12774): headers:
I/flutter (12774):  authorization: Bearer toosecrettotell
I/flutter (12774): 
I/flutter (12774): *** Response ***
I/flutter (12774): uri: https://api.mydomain.com/transcript/download/transcript/file/1
I/flutter (12774): statusCode: 200
I/flutter (12774): headers:
I/flutter (12774):  content-type: application/octet-stream
I/flutter (12774):  date: Fri, 16 Sep 2022 06:02:40 GMT
I/flutter (12774):  vary: Origin
I/flutter (12774):  content-length: 497741
I/flutter (12774): 
I/flutter (12774): 100
I/flutter (12774): true
D/Surface (12774): Surface::disconnect(this=0x73ae0c8000,api=1)
D/Surface (12774): Surface::disconnect(this=0x73ae0c8000,api=-1)
D/Surface (12774): Surface::disconnect(this=0x7357103000,api=1)
I/GED     (12774): ged_boost_gpu_freq, level 100, eOrigin 2, final_idx 2, oppidx_max 2, oppidx_min 0
V/PhoneWindow(12774): DecorView setVisiblity: visibility = 4, Parent = android.view.ViewRootImpl@c627c36, this = DecorView@f8b8737[MainActivity]

I tried using this code instead but it returned the same directory

  Future<String> getFileSavePath(String uniqueFileName) async {
    final Directory? dir = await getExternalStorageDirectory();
    String path = '${dir?.path}/$uniqueFileName';
    print("file download path");
    print(path);
    return path;
  }

My android/app/src/main/AndroidManifest.xml file:

<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="com.example">

    <uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE"/>
    <uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE"/>
    <uses-permission android:name="android.permission.INTERNET"/>

   <application

When I use a hard coded string path as suggested, I get this error:

E/flutter (25145): [ERROR:flutter/runtime/dart_vm_initializer.cc(41)] Unhandled Exception: FileSystemException: Cannot create file, path = '/storage/emulated/0/Download/fatsquid.jpg' (OS Error: Permission denied, errno = 13)

Answer 1

This question has been answered. Have you seen Flutter - save file to download folder - downloads_path_provider ?

path_provider will probably undergo some changes soon, there are some open issues:
https://github.com/flutter/flutter/issues/35783\ As of right now, the best way to get the download path on an Android device is to use:
/storage/emulated/0/Download/

The issue on https://github.com/flutter/flutter/issues/35783 has been closed without any solution on path_provider package

so you can use:

/storage/emulated/0/Download/

and you may make sure to add your permission on manifest.xml file:

<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />