android - Convert content:// to File:// -

i want know how can convert content:// file://. in application implement custom content provider , want convert content: // file://.

code:

content://com.abc.provider.local.file/mail/attachment/1.jpg want convert file://

string contentpath = localfileprovider.mail_file_uri + picture.getfilename();  uri photopath = uri.parse(contentpath);  

public string getrealpathfromuri(uri contenturi) {         string[] proj = { mediastore.images.media.data };         cursor cursor = managedquery(contenturi, proj, null, null, null);         int column_index = cursor.getcolumnindexorthrow(mediastore.images.media.data);         cursor.movetofirst();         return cursor.getstring(column_index);     }