protected void Page_Load(object sender, EventArgs e)
        {
            if (!IsPostBack)
            {
                Sessioninfo();
            }

            Session.Remove("info");
        }
		 private void Sessioninfo()
        {
            if (Session["info"] != null)
                tc.Text = Session["info"].ToString();
           
        }
		
		   private void  sessionadd() {
            Session.Add("info", tc.Text);
        }
		//事件中添加
		 sessionadd();