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Flutter – Write file in flash drive (android only)

Is it possible to save files to a flash drive using flutter?

I’m using a pendrive with a USB c port like this:
https://www.bestbuy.com/site/sandisk-ultra-dual-drive-go-1tb-usb-type-a-usb-type-c-flash-drive-black/6560692.p?skuId=6560692

I found this issue:
https://github.com/flutter/flutter/issues/40504

I’ve tried several things, path_provider doesn’t return directories correctly with getExternalStorageDirectories()

I have already added the permissions to the manifest and requested it with permission_handler

<uses-permission android:name="android.permission.MANAGE_EXTERNAL_STORAGE" />
<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE"
    android:maxSdkVersion="28" />
<uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE" />
<uses-permission android:name="android.permission.INTERNET"/>

I also tried with file_picker
await FilePicker.platform.getDirectoryPath();

But when selecting a folder on the flash drive the path it returns is just: /

I also tried using usb_serial:

final bytes = <int>[];

await yt.videos.streamsClient.get(audioStream).listen((chunk) {
  bytesReceived += chunk.length;
  bytes.addAll(chunk);

}, onDone: () async{
  MyLog.log('Done onDone');

}, onError: (error) async{
  MyLog.log('Done error: $error');

}).asFuture();

final devices = await UsbSerial.listDevices();
final port = await devices.first.create();
final openResult = await port?.open();

if ( !(openResult ?? false)) {
  MyLog.log("Failed to open");
  return;

}

port?.inputStream?.listen((Uint8List event) {
  MyLog.log('Event close');
  port.close();
});

await port?.write(Uint8List.fromList(bytes));

But it did not work

Tags:

2

Answers


  1. 0

    As you only need android, and aperently existing flutter solutions don’t work, you could make your own platform channel and create your needed methods for android native.

    Then, depending on which android version you target, directly accessing the SD-Card might not be possible at all, see this blog-post..

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  2. 0

    Try using Flutter’s platform channels to communicate with native Android code (Java or Kotlin) that handles the file operations on the USB drive.

    flutter:

    import 'package:flutter/services.dart';

class UsbStorage {
  static const platform = const MethodChannel('com.example.app/usb');
   ~~~code
}

    kotlin:

    class MainActivity: FlutterActivity() {
  private val CHANNEL = "com.example.app/usb"

  override fun configureFlutterEngine(@NonNull flutterEngine: FlutterEngine) {
~~~code
}
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