为什么查询Androids MediaStore会返回空光标？

Question

I'm using Android's MediaStore to retrieve duration/dateTaken of video files I record with my app. It works fine for older files, latest files I record do return empty (not null) cursor though. I cant see why this is happening, is MediaStore not updating instantly or there is a problem with the code I use below? Thanks for any help!

Uri uri = MediaStore.Video.Media.EXTERNAL_CONTENT_URI;
String selection = MediaStore.MediaColumns.DISPLAY_NAME + " LIKE '"+file.getName()+"'";
Cursor cursor = getContentResolver().query(uri, new String[]{MediaStore.Video.VideoColumns.DATE_TAKEN,MediaStore.Video.VideoColumns.DURATION}, selection, null, null);

Answer 1

I was also facing the same problem. Printing the stacktrace revieled the issue. Please add this permission in Manifest:

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

Answer 2

Seems like MediaScanner didn't scan latest files into MediaStore yet. You have to trigger if there are new files in your external storage.

sendBroadcast(new Intent(Intent.ACTION_MEDIA_MOUNTED, Uri.parse("file://"
                            + Environment.getExternalStorageDirectory())));

Answer 3

Check to make sure that having your Android device plugged in isn't messing with the external storage. If your phone is mounting as USB storage, then you won't have direct access to the files in external storage. You can check for this by opening the gallery while your phone is connected to your computer.

I just went through developing an app that had to access all of the pictures on the phone, and it doesn't work while the phone is plugged in. However, it works just fine if I unplug it.