DownloadManager manager = (DownloadManager) getSystemService(Context.DOWNLOAD_SERVICE);
    Uri uri = Uri.parse("https://www.netkiller.cn/linux/images/cover.png");
    DownloadManager.Request request = new DownloadManager.Request(uri);
    request.setNotificationVisibility(DownloadManager.Request.VISIBILITY_VISIBLE);
    long reference = manager.enqueue(request);