<asp:ScriptManager ID="ScriptManager1" runat="server">
</asp:ScriptManager> //ajax控件
<asp:UpdatePanel ID="UpdatePanel1" runat="server"> //使用ajax区域
<ContentTemplate>
<asp:Timer ID="timerCD" runat="server" Interval="1000" OnTick="timerCD_Tick">
</asp:Timer> //Timer控件,必须手写才能找到
<asp:Label ID="labDays" runat="server" Width="155px"></asp:Label><asp:Label ID="labTimes"
runat="server" Width="155px"></asp:Label> //显示
</ContentTemplate>
</asp:UpdatePanel>
后台：
private DateTime dtExam = DateTime.Parse("2012-10-09 08:40:29"); //定义时间
protected void Page_Load(object sender, EventArgs e)
{
}
protected void timerCD_Tick(object sender, EventArgs e) //双击Timer控件
{
if (this.dtExam < DateTime.Now) //如果设置的时间已过
{
this.timerCD.Enabled = false; //将Timmer置为false
labTimes.Text = "时间到！";
}
else
{
RefreshTime(); //刷新时间
}
}
private void RefreshTime() //刷新时间
{
TimeSpan ts = this.dtExam - DateTime.Now; //时间差
this.labDays.Text = ts.Days.ToString().PadLeft(2, '0') + "天";
this.labTimes.Text = ts.Hours.ToString().PadLeft(2, '0') + ":" + ts.Minutes.ToString().PadLeft(2, '0') + ":" + ts.Seconds.ToString().PadLeft(2, '0');
}