app终止后如何在后台使用download Manager下载多个文件？

<uses-permission android:name="android.permission.INTERNET" />
<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />

DownloadManager downloadManager = (DownloadManager) getSystemService(Context.DOWNLOAD_SERVICE);

DownloadManager.Request request = new DownloadManager.Request(Uri.parse(fileUrl));
request.setDestinationInExternalPublicDir(Environment.DIRECTORY_DOWNLOADS, fileName);
request.setNotificationVisibility(DownloadManager.Request.VISIBILITY_VISIBLE_NOTIFY_COMPLETED);

long downloadId = downloadManager.enqueue(request);

BroadcastReceiver receiver = new BroadcastReceiver() {
    @Override
    public void onReceive(Context context, Intent intent) {
        long id = intent.getLongExtra(DownloadManager.EXTRA_DOWNLOAD_ID, -1);
        if (id == downloadId) {
            // 下载完成后的处理逻辑
        }
    }
};
registerReceiver(receiver, new IntentFilter(DownloadManager.ACTION_DOWNLOAD_COMPLETE));