路径问题最后的出来的路径不对

Question

string str = Server.MapPath("~/manage/upload/");                System.IO.Directory.CreateDirectory(str + "/" + username + "/");                File1.PostedFile.SaveAs(str + "/" + username + "/" + username + newname);                string strr = Path.GetFileName(str + "/" + username + "/" + username + newname);//有错误                string strfile = Server.MapPath(strr);                super.Supervise_way = strfile;取出的路径不对老是出现错误