Android DownloadManager not working when redirected

问题

I'm working on an app that will download a zip file stored on Amazon S3 via a Rails Heroku server after authenticating via oAuth 2. Here's the flow:

1. Request to authenticate with the server running on Heroku via oAuth2.
2. Receive oAuth2 access token.
3. Request to download the zip file from the server (passing the oAuth token as bearer).
4. The server authorizes the request and redirects to an Amazon S3 URL containing a expiring signature (to stop anyone downloading the content without being authenticated).

At this point, I want the DownloadManager to just follow the redirect and get the zip file from S3, however it's failing. Is there some way I can work around this? Or is it just a limitation of DownloadManager?

I'm new to Android and still not totally up on the best debugging methods, so I don't have a lot of output to show you. However, it seems that DownloadManager.COLUMN_STATUS == DownloadManager.STATUS_FAILED and DownloadManager.COLUMN_REASON is returning "placeholder"!

EDIT - Here is the code I'm using. Edited to hide the client etc...

    @Override
public void onListItemClick(ListView l, View v, int position, long id) {
    Log.i("ChapterListActivity", "Item clicked: " + id);


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

    Uri uri = Uri.parse("http://myapphere.herokuapp.com/api/v1/volumes/2.zip");

    DownloadManager.Request request = new Request(uri);

    String accessToken = getSharedPreferences("keyhere", MODE_PRIVATE).getString("access_token", null); 

    Log.i("SLEChapterListActivity", "Getting file with access token... " + accessToken);

    request.addRequestHeader("Authorization", "Bearer " + accessToken);
    long reference = downloadManager.enqueue(request);

    IntentFilter filter = new IntentFilter(DownloadManager.ACTION_DOWNLOAD_COMPLETE);

    BroadcastReceiver receiver = new BroadcastReceiver() {
        @Override
        public void onReceive(Context context, Intent intent) {
            long downloadReference = intent.getLongExtra(DownloadManager.EXTRA_DOWNLOAD_ID, -1);
            Log.i("ChapterListActivity", "Download completed");


            Query query = new Query();
            query.setFilterById(downloadReference);

            Cursor cur = downloadManager.query(query);

            if (cur.moveToFirst()) {
            int columnIndex = cur.getColumnIndex(DownloadManager.COLUMN_STATUS);
            if (DownloadManager.STATUS_SUCCESSFUL == cur.getInt(columnIndex)) {
                String uriString = cur.getString(cur.getColumnIndex(DownloadManager.COLUMN_LOCAL_URI));

                File mFile = new File(Uri.parse(uriString).getPath());

            } else if (DownloadManager.STATUS_FAILED == cur.getInt(columnIndex)){
                String statusResult = cur.getString(cur.getColumnIndex(DownloadManager.COLUMN_REASON));
                Toast.makeText(context, "FAILED " + statusResult, Toast.LENGTH_SHORT).show();
            } else if (DownloadManager.ERROR_TOO_MANY_REDIRECTS == cur.getInt(columnIndex)){
                String statusResult = cur.getString(cur.getColumnIndex(DownloadManager.COLUMN_REASON));
                Toast.makeText(context, "TOO MANY REDIRS " + statusResult, Toast.LENGTH_SHORT).show();
            }
        }
        }
    };

    registerReceiver(receiver, filter);

}   

回答1:

I've found in Download Manager sources (line 500):

3xx: redirects (not used by the download manager)

It's not supported, yet.

In my current project, downloads are made in two steps:

1. Get Amazon url from our own server via oAuth2
2. Enqueue DownloadManager with the Amazon url.

If you don't like the two step process, I don't, then take a look at RoboSpice project, it has similar philosophy as DownloadManager.

回答2:

Just answering a sub-part of this question. The reason why you get the reason as a "placeholder" String is because the reason column is an integer, not a String. See Android DownloadManager: Download fails, but COLUMN_REASON only returns “placeholder”.

来源：https://stackoverflow.com/questions/13150587/android-downloadmanager-not-working-when-redirected