使用下载管理器将文件保存到内部存储中的隐藏文件夹中

File hiddenFolder = new File(Environment.getExternalStorageDirectory(), ".hidden_folder");
if (!hiddenFolder.exists()) {
    hiddenFolder.mkdirs();
}

DownloadManager.Request request = new DownloadManager.Request(Uri.parse(fileUrl));
request.setDestinationInExternalFilesDir(context, Environment.DIRECTORY_DOWNLOADS, ".hidden_folder");
DownloadManager downloadManager = (DownloadManager) getSystemService(Context.DOWNLOAD_SERVICE);
long downloadId = downloadManager.enqueue(request);

BroadcastReceiver receiver = new BroadcastReceiver() {
    @Override
    public void onReceive(Context context, Intent intent) {
        long downloadId = intent.getLongExtra(DownloadManager.EXTRA_DOWNLOAD_ID, -1);
        if (downloadId != -1) {
            DownloadManager downloadManager = (DownloadManager) getSystemService(Context.DOWNLOAD_SERVICE);
            DownloadManager.Query query = new DownloadManager.Query();
            query.setFilterById(downloadId);
            Cursor cursor = downloadManager.query(query);
            if (cursor.moveToFirst()) {
                int statusIndex = cursor.getColumnIndex(DownloadManager.COLUMN_STATUS);
                int status = cursor.getInt(statusIndex);
                if (status == DownloadManager.STATUS_SUCCESSFUL) {
                    int uriIndex = cursor.getColumnIndex(DownloadManager.COLUMN_LOCAL_URI);
                    String downloadedUriString = cursor.getString(uriIndex);
                    if (downloadedUriString != null) {
                        File downloadedFile = new File(Uri.parse(downloadedUriString).getPath());
                        File hiddenFolder = new File(Environment.getExternalStorageDirectory(), ".hidden_folder");
                        File destinationFile = new File(hiddenFolder, downloadedFile.getName());
                        downloadedFile.renameTo(destinationFile);
                    }
                }
            }
            cursor.close();
        }
    }
};

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