Android DownloadManager Progress
Solution 1:
I am looking for a better way of doing this also, but so far I am planning to just poll for progress every 1sec or so.
DownloadManager mgr = (DownloadManager) context.getSystemService(Context.DOWNLOAD_SERVICE);
long id = mgr.enqueue(request);
DownloadManager.Query q = new DownloadManager.Query();
q.setFilterById(id);
Cursor cursor = mgr.query(q);
cursor.moveToFirst();
int bytes_downloaded = cursor.getInt(cursor.getColumnIndex(DownloadManager.COLUMN_BYTES_DOWNLOADED_SO_FAR));
cursor.close();
Edit:
A FileObserver
can help with this. This is the skeleton of one I have put together to help keep track of which files our app has downloaded. Start it in an activity or service's onStart
and stop it in onStop
. Combined with a manual synchronization of the state of things during onStart
, this can give you a pretty complete picture of what's going on.
For progress in particular, watching for the OPEN/CLOSE_WRITE events can help you decide when to start/stop polling the DownloadManager for updates.
public class DownloadsObserver extends FileObserver {
public static final String LOG_TAG = DownloadsObserver.class.getSimpleName();
private static final int flags =
FileObserver.CLOSE_WRITE
| FileObserver.OPEN
| FileObserver.MODIFY
| FileObserver.DELETE
| FileObserver.MOVED_FROM;
// Received three of these after the delete event while deleting a video through a separate file manager app:
// 01-16 15:52:27.627: D/APP(4316): DownloadsObserver: onEvent(1073741856, null)
public DownloadsObserver(String path) {
super(path, flags);
}
@Override
public void onEvent(int event, String path) {
Log.d(LOG_TAG, "onEvent(" + event + ", " + path + ")");
if (path == null) {
return;
}
switch (event) {
case FileObserver.CLOSE_WRITE:
// Download complete, or paused when wifi is disconnected. Possibly reported more than once in a row.
// Useful for noticing when a download has been paused. For completions, register a receiver for
// DownloadManager.ACTION_DOWNLOAD_COMPLETE.
break;
case FileObserver.OPEN:
// Called for both read and write modes.
// Useful for noticing a download has been started or resumed.
break;
case FileObserver.DELETE:
case FileObserver.MOVED_FROM:
// These might come in handy for obvious reasons.
break;
case FileObserver.MODIFY:
// Called very frequently while a download is ongoing (~1 per ms).
// This could be used to trigger a progress update, but that should probably be done less often than this.
break;
}
}
}
Usage would be something like this:
public class MyActivity extends Activity {
private FileObserver fileObserver = new DownloadsObserver(
getExternalFilesDir(Environment.DIRECTORY_DOWNLOADS).getAbsolutePath());
@Override
protected void onStart() {
super.onStart();
fileObserver.startWatching();
syncUpDatabaseWithFileSystem();
}
@Override
protected void onStop() {
fileObserver.stopWatching();
super.onStop();
}
}
Solution 2:
It turns out that the FileObserver
implementation on Marshmallow has a bug. As a result, FileObserver
will not report any modifications of a file downloaded by the download manager. (Older Android versions do not have this issue – it works fine on KitKat.) Source
For me, the following code (based on this answer) works well. I poll every second – I've tried halving that interval, but without any visible effect.
private static final int PROGRESS_DELAY = 1000;
Handler handler = new Handler();
private boolean isProgressCheckerRunning = false;
// when the first download starts
startProgressChecker();
// when the last download finishes or the Activity is destroyed
stopProgressChecker();
/**
* Checks download progress.
*/
private void checkProgress() {
DownloadManager.Query query = new DownloadManager.Query();
query.setFilterByStatus(~(DownloadManager.STATUS_FAILED | DownloadManager.STATUS_SUCCESSFUL));
Cursor cursor = downloadManager.query(query);
if (!cursor.moveToFirst()) {
cursor.close();
return;
}
do {
long reference = cursor.getLong(cursor.getColumnIndex(DownloadManager.COLUMN_ID));
long progress = cursor.getLong(cursor.getColumnIndex(DownloadManager.COLUMN_BYTES_DOWNLOADED_SO_FAR));
// do whatever you need with the progress
} while (cursor.moveToNext());
cursor.close();
}
/**
* Starts watching download progress.
*
* This method is safe to call multiple times. Starting an already running progress checker is a no-op.
*/
private void startProgressChecker() {
if (!isProgressCheckerRunning) {
progressChecker.run();
isProgressCheckerRunning = true;
}
}
/**
* Stops watching download progress.
*/
private void stopProgressChecker() {
handler.removeCallbacks(progressChecker);
isProgressCheckerRunning = false;
}
/**
* Checks download progress and updates status, then re-schedules itself.
*/
private Runnable progressChecker = new Runnable() {
@Override
public void run() {
try {
checkProgress();
// manager reference not found. Commenting the code for compilation
//manager.refresh();
} finally {
handler.postDelayed(progressChecker, PROGRESS_DELAY);
}
}
};