Show Download Manager progress inside activity

Question

I used Download Manager class inside my activity to perform downloads; it works fine and my next task is to show the same progress percentage inside my activity. I am not sure how to do it.

My code so far

public class DownloadSampleBook extends Activity{

private long enqueue;
private DownloadManager dm;

/** Called when the activity is first created. */
@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_sample_download);

    BroadcastReceiver receiver = new BroadcastReceiver() {
        @Override
        public void onReceive(Context context, Intent intent) {
            String action = intent.getAction();
            if (DownloadManager.ACTION_DOWNLOAD_COMPLETE.equals(action)) {
                long downloadId = intent.getLongExtra(
                        DownloadManager.EXTRA_DOWNLOAD_ID, 0);
                Query query = new Query();
                query.setFilterById(enqueue);
                Cursor c = dm.query(query);
                if (c.moveToFirst()) {
                    int columnIndex = c
                            .getColumnIndex(DownloadManager.COLUMN_STATUS);
                    if (DownloadManager.STATUS_SUCCESSFUL == c
                            .getInt(columnIndex)) {

                       view.setImageURI(Uri.parse(uriString));
                    }
                }
            }
        }
    };

    registerReceiver(receiver, new IntentFilter(
            DownloadManager.ACTION_DOWNLOAD_COMPLETE));
}

public void onClick(View view) {
    dm = (DownloadManager) getSystemService(DOWNLOAD_SERVICE);
    Request request = new Request(
            Uri.parse("http://abc.com/a.png"));
    enqueue = dm.enqueue(request);

}

public void showDownload(View view) {
    Intent i = new Intent();
    i.setAction(DownloadManager.ACTION_VIEW_DOWNLOADS);
    startActivity(i);
}
}

Is there any method that give the progress download percentage?

Answer 1

If you are looking for a decent way to determine when to query the DownloadManager for progress updates, consider registering a ContentObserver for the uri content://downloads/my_downloads

Example:

DownloadManager manager = (DownloadManager) getSystemService( Context.DOWNLOAD_SERVICE );
manager.enqueue( myRequest );

Uri myDownloads = Uri.parse( "content://downloads/my_downloads" );
getContentResolver().registerContentObserver( myDownloads, true, new DownloadObserver() );

...

public static class DownloadObserver extends ContentObserver {
   @Override
   public void onChange( boolean selfChange, Uri uri ) {
      Log.d( "DownloadObserver", "Download " + uri + " updated" );
   }

This yields the following output as each chunk of the long running download is received

D/DownloadObserver(15584): Download content://downloads/my_downloads/437 updated
D/DownloadObserver(15584): Download content://downloads/my_downloads/437 updated
D/DownloadObserver(15584): Download content://downloads/my_downloads/437 updated
D/DownloadObserver(15584): Download content://downloads/my_downloads/437 updated

where '437' is the ID of your download.

Note that this follows the content URI defined in the class android.provider.Downloads which appears to be hidden in the framework and may not work consistently on all devices. (https://android.googlesource.com/platform/frameworks/base/+/refs/heads/master/core/java/android/provider/Downloads.java#89)

Answer 2

You can query the number of bytes downloaded so far, and the total number of bytes that need to be downloaded, using the query method, in much the same way as you have queried the status in your example code. Once you have those values, it's fairly easy to calculate the progress as a percentage.

There doesn't appear to be any way for you to be notified when new data is received, so it would be up to you to poll the download manager at some regular interval to determine the current status of any download that you want to monitor.

Query query = new Query();
query.setfilterById(downloadId);

Cursor c = dm.query(query);
if (c.moveToFirst()) {
  int sizeIndex = c.getColumnIndex(DownloadManager.COLUMN_TOTAL_SIZE_BYTES);
  int downloadedIndex = c.getColumnIndex(DownloadManager.COLUMN_BYTES_DOWNLOADED_SO_FAR);
  long size = c.getInt(sizeIndex);
  long downloaded = c.getInt(downloadedIndex);
  double progress = 0.0;
  if (size != -1) progress = downloaded*100.0/size;  
  // At this point you have the progress as a percentage.
}

Note that the total size will initially be -1 and will only be filled in once the download starts. So in the sample code above I've checked for -1 and set the progress to 0 if the size is not yet set.

However, you may find in some cases that the total size is never returned (for example, in an HTTP chunked transfer, there will be no Content-Length header from which the size can be determined). If you need to support that kind of server, you should probably provide some kind of indication to the user that the download is progressing and not just a progress bar that is stuck at zero.