Как да изтеглите файл с услуга в android?

Искам да изтегля файл от интернет с услуга. Намерих изходния код и кодът работи добре. Но имам проблем, когато се върна от приложението, изтеглянето спира или когато изчистя RAM, то също спира. Така че искам намерен код за изтегляне като Google Play, който никога не спира, когато изчисти RAM или хронологията на приложенията. Това е моят изходен код:

public class Temp extends IntentService {
public static final int UPDATE_PROGRESS = 8344;
private int lastupdate=0;
private NotificationManager nm;
private Builder mBuilder;
public Temp() {

    super("Temp");


}

@Override
public int onStartCommand(Intent intent, int flags, int startId) {
    Log.d("SERVICE-ONCOMMAND", "onStartCommand");
    return START_STICKY;
 }

@Override
protected void onHandleIntent(Intent intent) {
    Log.e("ok","ok");
    nm = (NotificationManager)  getSystemService(NOTIFICATION_SERVICE);
    mBuilder = new NotificationCompat.Builder(this);
    mBuilder.setContentTitle(
            "Picture Download dnsadg sadgasjdgashgd asgd asjdg asjgd sajgd s")
            .setContentText("Download in progress")
            .setSmallIcon(R.drawable.icon_app).setContentInfo("0%");

    mBuilder.setOngoing(true);  
    File root = new File(Environment.getExternalStorageDirectory()
            + "/aaaa");
    String urlToDownload = "http://dl2.mid.az/endir.php?file=uploads/Exclusive/miri_yusif_-_yoxam_men_mp3.mid.az.mp3";
   // ResultReceiver receiver = (ResultReceiver) intent.getParcelableExtra("receiver");
    try {
        URL url = new URL(urlToDownload);
        URLConnection connection = url.openConnection();
        connection.connect();
        // this will be useful so that you can show a typical 0-100% progress bar
        int fileLength = connection.getContentLength();

        // download the file
        InputStream input = new BufferedInputStream(url.openStream());
        OutputStream output = new FileOutputStream(new File(root.getPath(),
                "ok.mp3"));

        byte data[] = new byte[1024];
        long total = 0;
        int count;
        while ((count = input.read(data)) != -1) {
            total += count;

            progressChange((int)(total * 100) / fileLength);
            // publishing the progress....
         //   Bundle resultData = new Bundle();
         //   resultData.putInt("progress" ,(int) (total * 100 / fileLength));
         //   receiver.send(UPDATE_PROGRESS, resultData);
            output.write(data, 0, count);
        }

        output.flush();
        output.close();
        input.close();
    } catch (IOException e) {
        e.printStackTrace();
    }

   // Bundle resultData = new Bundle();
  //  resultData.putInt("progress" ,100);
  //  receiver.send(UPDATE_PROGRESS, resultData);
}

@Override
public void onDestroy() {
    Log.e("DESTROY", "DESTROY");
    super.onDestroy();
}
void progressChange(int progress){


    if (lastupdate != progress) {
        lastupdate = progress;
        // not.contentView.setProgressBar(R.id.status_progress,
        // 100,Integer.valueOf(progress[0]), false);
        // inform the progress bar of updates in progress
        // nm.notify(42, not);
        if (progress < 100) {
            mBuilder.setProgress(100, Integer.valueOf(progress),
                    false).setContentInfo(progress+"%");
            nm.notify(12, mBuilder.build());
               Intent i = new Intent("com.russian.apps.TabActivity").putExtra("some_msg",progress+"%");
                this.sendBroadcast(i);
        } else {
            mBuilder.setContentText("Download complete")
            // Removes the progress bar
                    .setProgress(0, 0, false).setOngoing(false).setContentInfo("");;

            nm.notify(12, mBuilder.build());

        }

    }

}
}