玩弄我的缓存应用程序，我希望时间戳留在屏幕上，但回发后它会消失

Question

.Net 4.8

为什么我缓存列表框后，我的服务器端 label 控件上的时间戳没有保留？ 我不指望它会更新，但我确实希望它在那里并且不会消失。

<%@ Page Title="" Language="C#" MasterPageFile="~/Site.Master" AutoEventWireup="true" CodeBehind="CacheApp.aspx.cs" Inherits="CachePractice.CacheApp" %>

<asp:Content ID="Content1" ContentPlaceHolderID="MainContent" runat="server">
    <div class="jumbotron">
        <h1>Cache App, Get it?</h1>
    </div>
    <div>

        <div>
            <asp:Label ID="LabelCurrentTime" runat="server"></asp:Label>
            <asp:Button ID="Button1" runat="server" Text="Add value to cache" OnClick="Button1_Click" />
            <asp:Button ID="Button2" runat="server" Text="Remove cache" OnClick="Button2_Click" /><br />
            <asp:ListBox ID="ListBox1" runat="server"></asp:ListBox>
        </div>

    </div>
</asp:Content>

代码隐藏：

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;

namespace CachePractice
{
    public partial class CacheApp : System.Web.UI.Page
    {
        protected void Page_Load(object sender, EventArgs e)
        {

            if (Cache["WeekData"] != null)
            {
                ListBox1.DataSource = Cache["WeekData"];
                ListBox1.DataBind();
            }
            else
            {
                ListBox1.DataSource = null;
                ListBox1.DataBind();

                LabelCurrentTime.Text = DateTime.Now.ToLongTimeString();
            }
        }
        protected void Button1_Click(object sender, EventArgs e)
        {
            List<string> list = new List<string>();
            list.Add("Sunday");
            list.Add("Monday");
            list.Add("Tuesday");
            list.Add("Wednesday");
            list.Add("Thursday");
            list.Add("Friday");
            list.Add("Saturday");
            Cache["WeekData"] = list;
        }
        protected void Button2_Click(object sender, EventArgs e)
        {
            Cache.Remove("WeekData");
        }
    }
}