ASP.NET如何接收清楚缓存的通知

1 如果使用cache的add方法或者接受CacheItemPriority值得Insert方法重载接收通知，可以提供CacheItemRemovedCallBack对象，选择在清除对象时接收通知

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

namespace Cachting
{
    public partial class Default : System.Web.UI.Page
    {
        private static readonly string CACHE_KEY = "codebehind_ts";
        protected void Page_Load(object sender, EventArgs e)
        {

        }

        public string GetTime()
        {
            string ts = (string)Cache[CACHE_KEY];
            if (ts==null)
            {
                Cache[CACHE_KEY]=ts= DateTime.Now.ToLongTimeString();
                Cache.Insert(CACHE_KEY, ts, null, Cache.NoAbsoluteExpiration, TimeSpan.FromSeconds(),
                    System.Web.Caching.CacheItemPriority.Normal, HandleRemoveNotification);
            }
            else
            {
                ts += "<b>(Cached)</b>";
            }
            return ts;
        }

        private void HandleRemoveNotification(string key, object value, CacheItemRemovedReason reason)
        {
            string cacheData = (string)Cache[CACHE_KEY];
            cacheData = cacheData + "10 秒之后的清楚缓存数据的通知";
            Response.Write("<Script Language='JavaScript'>window.alert('" + cacheData.ToString() + "');</script>");
        }
    }
}

示例代码如上