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);

    }

}