List<int> list = new List<int>();

        list.Add(1);

        list.Add(2);

        list.Add(3);

        Cache["Key"] = list;

        var list2 = Cache["Key"] as List<int>;

        List<int> listNew = list2;

        listNew.Add(4);

        if (list2 != null && list2.Count > 0)

        {

            foreach (int i in list2)

            {

                Response.Write(i + "<br/>");

            }

        }
结果1234