Get file name from headers with DownloadManager in Android

Question

I'm using DownloadManager to download video files from a url.

The problem is if I use the default folder to download the file I can not see the video in the galery.

Also, If I try to use this method:

request.setDestinationInExternalPublicDir(Environment.DIRECTORY_DOWNLOADS, 'filename');

I need to know the file name before download which in this case, I don't.

And also, I don't have the name of the file in the url.

How can I do to get the file name from the headers and pass the name to the method setDestinationInExternalPublicDir ? Other alternatives?

"The problem is if I use the default folder to download the file I can not see the video in the galery" -- what did you do to make it show up in the Gallery? Did you use `MediaScannerConnnection` and `scanFile()`? Otherwise, it will not show up until the next periodic round of file indexing, which may be a while. "I need to know the file name before download which in this case, I don't" -- then issue an HTTP `HEAD` request or something so that you can get the filename. — CommonsWare, Apr 14 '14 at 20:56
What it doesn't make sense to me is why DonwloadManager doesnt't provide a way to set just the destination folder and keep the name of the file from the server. I'm missing something here? Thanks for your time again. — rodeleon, Apr 14 '14 at 22:28
That'd be a nice feature, but `DownloadManager` doesn't offer it. — CommonsWare, Apr 14 '14 at 22:30
Getting file name from the download response header? I think this would be a basic feature of a "DownloadManager". It's just frustrating to work with Android at times. — Robert Kang, May 14 '14 at 13:24

score 10 · Accepted Answer · answered Apr 19 '14 at 01:56

In case anyone want an implementation of doing a HEAD request to get the filename:

class GetFileName extends AsyncTask<String, Integer, String>
{
    protected String doInBackground(String... urls)
    {
        URL url;
        String filename = null;
        try {
            url = new URL(urls[0]);
            String cookie = CookieManager.getInstance().getCookie(urls[0]);
            HttpURLConnection con = (HttpURLConnection) url.openConnection();
            con.setRequestProperty("Cookie", cookie);
            con.setRequestMethod("HEAD");
            con.setInstanceFollowRedirects(false);
            con.connect();

            String content = con.getHeaderField("Content-Disposition");
            String contentSplit[] = content.split("filename=");
            filename = contentSplit[1].replace("filename=", "").replace("\"", "").trim();
        } catch (MalformedURLException e1) {
            e1.printStackTrace();
        } catch (IOException e) {
        }
        return filename;
    }

    @Override
    protected void onPreExecute() {
        super.onPreExecute();
    }
    @Override
    protected void onPostExecute(String result) {

    }
}

Thanks! So there is no way to do it with the DownloadManager? :( I am downloading files from Google Drive and the only way to extract the file name is reading the headers — lasnow, Mar 16 '19 at 00:44

score 4 · Answer 2 · answered Feb 28 '17 at 16:03

4

Small tip, there is a nice helper method in Android

URLUtil.guessFileName(url, contentDisposition, contentType);

So after completing the call to the server, getting the contenttype and contentDisposition from the Headers this will try and find the filename from the information.

answered Feb 28 '17 at 16:03

Raanan

4,777
27
47

A simple and effective solution. Thanks – OMi Shah Oct 16 '19 at 03:56
Unfortunately, this solution does not support filename* value from rfc https://tools.ietf.org/html/rfc5987 – HotIceCream Apr 06 '21 at 13:38

score 0 · Answer 3 · answered Apr 18 '19 at 07:24

I got into the same problem.I used @rodeleon answer but there was no Content-Disposition in response header. Then I analyzed url header from Chrome dev tools and got 'Location' in response header which contained filename at the end, it was like "b/Ol/fire_mp3_24825.mp3". so instead of using

String content = con.getHeaderField("Content-Disposition")

I used

String content = con.getHeaderField("Location")

and at the end in onPostExecute

    protected void onPostExecute(String result) {
        super.onPostExecute(result);
        String fileName = result.substring(result.lastIndexOf("/") + 1);
        // use result as file name
        Log.d("MainActivity", "onPostExecute: " + fileName);
    }

Martin Zeitler · Answer 4 · 2020-09-23T12:12:32.410

Method URLUtil.guessFileName() (while not yet knowing about the Content-Disposition) and also the meanwhile deprecated class AsyncTask are both kinda problematic approaches these days. To properly enqueue the download with the DownloadManager:

One first has to disable "following redirects" in whatever HTTP client (that's the clue).
Then the first response will be HTTP 302 (with a Location header), instead of HTTP 200.
When fetching that, one will get HTTP 200 with a Content-Disposition header (filename).
Only then one can enqueue with DownloadManager (whilst knowing the filename already).

Here's an example of mine: RepositoryFragment (a GitHub Client).

score -4 · Answer 5 · answered Apr 20 '16 at 21:10

-4

    request.setDestinationInExternalPublicDir(Environment.DIRECTORY_MOVIES, uri.getLastPathSegment());

answered Apr 20 '16 at 21:10

user3726663

1
3

Does not use headers. – Andrew Gaul Sep 21 '18 at 15:55

Get file name from headers with DownloadManager in Android

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