ASP.NET缓存 Cache

// 保存缓存  null 表示缓存依赖
// 键,值,缓存依赖对象,绝对过期时间,区间
Cache.Insert("user","xgao",null,DateTime.Now.AddSeconds(10),TimeSpan.Zero);

// 简单保存缓存
Cache["test"] = "这是一个测试！";

//读取缓存
lbl.text = Cache["user"];

protected void Page_Load(object sender, EventArgs e)
{
    
    if (Cache["fileText"] == null)
    {
    Response.Write("文件被修改,缓存被删除,但又创建了新的缓存,下次访问可得到！");
    // 得到指定文件的物理路径
    string filePath = Server.MapPath("~/CacheDep.txt");
    // 读取指定文件
    string Text = File.ReadAllText(filePath);

    // 创建缓存的文件依赖对象(依赖的文件的服务物理路径)
    CacheDependency cDep = new CacheDependency(filePath);
    // 键,值,缓存依赖对象,无绝对过期时间,无滑动过期时间,优先级,更新回调函数
    Cache.Insert("fileText", Text, cDep,
        System.Web.Caching.Cache.NoAbsoluteExpiration, System.Web.Caching.Cache.NoSlidingExpiration, 
        System.Web.Caching.CacheItemPriority.Normal, callback);
    }
    else
    {
    Response.Write(Cache["fileText"].ToString());
    }
}

// 缓存依赖的回调函数(当缓存被清除时调用些方法)
public void callback(string key, object value, CacheItemRemovedReason reason)
{
    string filePath = Server.MapPath("~/CacheLog.txt");
    string msg = "Cache["+key+"]="+value+"缓存被移除,因为:"+reason+"\r\n";
    File.AppendAllText(filePath, msg);
}

create Trigger [bankTri]
on [bank]
for insert,update,delete
as
  update BankVer set VerNum=VerNum+1

<caching>
  <sqlCacheDependency enabled="true">
    <databases>
        <!-- pollTime为轮询时间间隔 15 秒  -->
    <add name="DepName" connectionStringName="conStr" pollTime="15000"/>
    </databases>
  </sqlCacheDependency>
</caching>

 <form id="form1" runat="server">
    <div>
        <asp:GridView ID="gvBankList" runat="server"></asp:GridView>
    </div>
  </form>

 protected void Page_Load(object sender, EventArgs e)
        {
            if (Cache["bankList"] == null)
            {
                Response.Write("数据以更改！以下从数据库读取的！</br>");

                DataTable dt = GetBankList();
                gvBankList.DataSource = dt;
                gvBankList.DataBind();

                SqlCacheDependency sqlDep = new SqlCacheDependency("DepName", "BankVer");
                Cache.Insert("bankList", dt, sqlDep, System.Web.Caching.Cache.NoAbsoluteExpiration, System.Web.Caching.Cache.NoSlidingExpiration, CacheItemPriority.Normal,callback);

            }
            else
            {
                Response.Write("以下是从缓存里读取的</br>");
                gvBankList.DataSource = Cache["bankList"];
                gvBankList.DataBind();
            }
        }
        public void callback(string key,object value,CacheItemRemovedReason reason)
        {
            string filePath = Server.MapPath("~/CacheLog.txt");
            string msg = "数据库依赖 Cache[" + key + "]=" + value + "缓存被移除,因为:" + reason + "\r\n";
            File.AppendAllText(filePath, msg);
        }

        public DataTable GetBankList()
        {
            string connStr = ConfigurationManager.ConnectionStrings["ConnStr"].ConnectionString;
            SqlConnection conn = new SqlConnection(connStr);
            SqlCommand cmd = conn.CreateCommand();
            cmd.CommandText = "select * from bank";

            DataSet ds = new DataSet();
            SqlDataAdapter sda = new SqlDataAdapter(cmd);
            sda.Fill(ds);
            return ds.Tables[0];
        }