transfer_manager_android #

Android implementation of the transfer_manager platform contract.

The native milestone supports durable HTTP downloads, streamed multipart uploads, and resumable TUS uploads through WorkManager. It also provides foreground progress notifications, network constraints, task reconnection, atomic .part download completion, cancellation, and persistent pause/resume actions on active notifications.

Core integration #

final manager = TransferManager(
  engines: [
    AndroidBackgroundDownloadEngine(),
    AndroidBackgroundTusUploadEngine(),
    AndroidBackgroundUploadEngine(),
    TusTransferEngine(),
    HttpTransferEngine(),
  ],
);
await manager.initialize();

The engine maps the existing DownloadRequest and task identifier to durable native work, reconnects after Dart or Android process recreation, and forwards native progress into the core task event stream.

Partial files are resumed with Range and a persisted ETag or Last-Modified validator in If-Range, preventing a changed remote resource from being appended to stale bytes.

After a successful download, Android posts a separate completion notification even when the Flutter application is currently visible. Tapping it opens the downloaded file through a non-exported FileProvider with a temporary read-only URI grant. Destinations must be within app storage or shared external storage so they can be exposed safely.

On Android 13 and newer, the host application must request POST_NOTIFICATIONS at runtime. The permission is declared by this plugin, but Android does not allow a library to display notifications after the user has denied that permission.

final android = TransferManagerAndroid();
if (!await android.notificationsEnabled()) {
  final granted = await android.requestNotificationPermission();
  // Continue without notifications if the user declines.
}

To publish a completed download in the user-visible system Downloads folder on Android 10 and newer, use the MediaStore-backed destination helper:

DownloadRequest(
  source: Uri.parse('https://example.com/report.pdf'),
  destination: const TransferDestination.downloads('report.pdf'),
);

This does not require broad storage permission. The file becomes visible to the user only after the staged download has completed.

Short-lived authorization and cookie headers are rejected because WorkManager persists its input data. Public or presigned URLs are supported in this milestone. Multipart upload retries restart the request; TUS uploads persist their server-created URL and acknowledged offset so retries resume in bounded chunks.