.net 之缓存

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;
using DBHelper;
using System.Data;
using MySql.Data.MySqlClient;
using System.Web.Caching;

public partial class 缓存过期 : System.Web.UI.Page
{
    static bool itemremove = false;
    static CacheItemRemovedReason reson;
    CacheItemRemovedCallback onremove = null;

    public void removeCallback(string k, object v, CacheItemRemovedReason r) {

        itemremove = true;
        reson = r;
    }
    protected void Page_Load(object sender, EventArgs e)
    {
        DataSet ds = (DataSet)Cache["students"];
        if (ds == null) {
            ds = GetStudent();
            onremove=new CacheItemRemovedCallback(this.removeCallback);
            CacheDependency cd=new CacheDependency(Server.MapPath("web.config"));
            Cache.Insert("students", ds, cd, Cache.NoAbsoluteExpiration, TimeSpan.FromHours(1), CacheItemPriority.High, onremove);

        }
        GridView1.DataSource = ds;
        GridView1.DataBind();
    }
    protected void Button1_Click(object sender, EventArgs e)
    {
        if (Cache["students"] != null) {
            Cache.Remove("students");

        }
        if (itemremove)
        {

            Label1.Text += "REmove触发";
            Label1.Text += "<br>";
            Label1.Text += reson.ToString();
        }
        else {
            Label1.Text += Server.HtmlEncode(Cache["students"] as string);

        }
    }

    public static void SetCache(string CacheKey, object objObject, System.Web.Caching.CacheDependency dep)
    {
        System.Web.Caching.Cache objCache = HttpRuntime.Cache;
        objCache.Insert(
            CacheKey,
            objObject,
            dep,
            System.Web.Caching.Cache.NoAbsoluteExpiration, //从不过期
            System.Web.Caching.Cache.NoSlidingExpiration, //禁用可调过期
            System.Web.Caching.CacheItemPriority.Default,
            null);
    }

    public static object GetCache(string CacheKey)
    {
        System.Web.Caching.Cache objCache = HttpRuntime.Cache;
        return objCache[CacheKey];
    }

    public DataSet GetStudent()
    {
        string sql = "select * from t_student";
        return SqlHelper.ExecuteDataSetText(sql);
    }

}