对于本地视频，Cursor始终返回NULL以从文件资源管理器中获取路径

Question

从本地存储中获取视频路径时，始终在游标对象中获取空值

public String getPath(Uri uri){
    Log.i(TAG,"inside getpath");
    String[] filePathColumn={MediaStore.Video.Media.DATA};
    Cursor cursor=getContentResolver().query(uri, filePathColumn, null, null, null);
    Log.i(TAG,"bloody cursor = "+cursor);if (cursor != null) {
        // HERE YOU WILL GET A NULLPOINTER IF CURSOR IS NULL
        // THIS CAN BE, IF YOU USED OI FILE MANAGER FOR PICKING THE MEDIA
        int column_index = cursor.getColumnIndexOrThrow(MediaStore.Video.Media.DATA);
        cursor.moveToFirst();
        Log.i(TAG,"exit  if get path");
        return cursor.getString(column_index);
    } else{
        Log.i(TAG,"exit else get path");
        return null;
    }
}

错误记录如下：

03-11 15:10:04.415 1758-1758/com.example.vivekgandhi.playvideoapp I/MyMessage: bloody cursor = null 
03-11 15:10:04.415 1758-1758/com.example.vivekgandhi.playvideoapp I/MyMessage: exit else get path