AJAX——使用Timer来控制内容背景

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源视图代码：

 1 <%@ Page Language="C#" AutoEventWireup="true" CodeFile="Default.aspx.cs" Inherits="_Default" %>
 2 
 3 <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.1//EN" "http://www.w3.org/TR/xhtml11/DTD/xhtml11.dtd">
 4 <html xmlns="http://www.w3.org/1999/xhtml">
 5 <head id="Head1" runat="server">
 6     <title>Timer Example Page</title>
 7     <link href="DivStyles.css" rel="stylesheet" type="text/css" />
 8 </head>
 9 <body>
10     <form id="form1" runat="server">
11     <asp:ScriptManager ID="ScriptManager1" runat="server" />
12     <asp:Timer ID="Timer1" OnTick="Timer1_Tick" runat="server" Interval="1000" />
13     <br />
14     <hr />
15     <br />
16     Some content ..............<br />
17     <br />
18     <asp:UpdatePanel ID="BannerPanel" runat="server" UpdateMode="Conditional">
19         <Triggers>
20             <asp:AsyncPostBackTrigger ControlID="Timer1" />
21         </Triggers>
22         <ContentTemplate>
23             <asp:Image ID="BannerImage" runat="server" ImageUrl="~/banners/banner_1.gif" />&nbsp;
24         </ContentTemplate>
25     </asp:UpdatePanel>
26     <br />
27     <div>
28         &nbsp;Some more content ..........<br />
29         <br />
30     </div>
31     </form>
32 </body>
33 </html>

1   protected void Timer1_Tick(object sender, EventArgs e)
2     {
3         Random RandomClass = new Random();
4         int n = RandomClass.Next(1, 9);
5         BannerImage.ImageUrl = System.String.Concat("banners/Banner_", n.ToString(), ".gif");
6     }

代码的作用是产生1-9的任意随机数，来选择不同的图片的呈现。