Asp.net ajax实现任务提示页面的简单代码

%@ Page Language="C#" %>
!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN"
"http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
script runat="server">
    void WaitFiveSeconds(object o, EventArgs e)
    {
        System.Threading.Thread.Sleep(5000);
        Label1.Text = DateTime.Now.ToLongTimeString( );
    }
/script>
html xmlns="http://www.w3.org/1999/xhtml">
head id="Head1" runat="server">
title>ASP.NET AJAX/title>
/head>
body>
form id="form1" runat="server">
    asp:ScriptManager ID="ScriptManager1" runat="server" />
    asp:UpdatePanel ID="UpdatePanel1" runat="server">
        ContentTemplate>
            asp:Button ID="Button1" runat="server" Text="Do something" OnClick="WaitFiveSeconds" />br />
            asp:Label ID="Label1" runat="server" />
        /ContentTemplate>
    /asp:UpdatePanel>
    asp:UpdateProgress ID="UpdateProgress1" runat="server" AssociatedUpdatePanelID="UpdatePanel1">
        ProgressTemplate>
        div style="position: absolute; left: 200px; top: 150px; border: solid 1px black; padding:4px;">
            Loading, please stand by ...
        /div>
        /ProgressTemplate>
    /asp:UpdateProgress>
/form>
/body>
/html>