Random rnd = new Random();
            int n = rnd.Next(100000, 999999);
            try
            {
               // Session["code"] = n.ToString();
               //Session.Add("code", n.ToString());
                Session["code"] = "123123";
            }
            catch (Exception e)
            {
                Console.WriteLine(e.ToString());
                return isbool;
            }
session老报“未将对象引用设置到对象实例”?