ASP.NET AJAX 初学
今天看了一点ASP.NET AJAX，知道了如何用UpdatePanel,呵呵，下面是示例代码：
1
<
table border
=
"
1
"
width
=
"
800
"
bgcolor
=
"
#99FF99
"
align
=
"
center
"
>
2
<
tr
>
3
<
td
>
4
<
asp:Label ID
=
"
Label1
"
runat
=
"
server
"
Text
=
"
User List：
"
>
</
asp:Label
>
5
6
</
td
>
7
</
tr
>
8
<
tr
>
9
<
td
>
10
<
asp:UpdatePanel ID
=
"
UpdatePanel1
"
runat
=
"
server
"
UpdateMode
=
"
Conditional
"
>
11
<
ContentTemplate
>
12
<
asp:Label ID
=
"
lbUserList
"
runat
=
"
server
"
Text
=
""
>
</
asp:Label
>
13
</
ContentTemplate
>
14
<
Triggers
>
15
<
asp:AsyncPostBackTrigger ControlID
=
"
Timer1
"
/>
16
</
Triggers
>
17
</
asp:UpdatePanel
>
18
<
asp:Timer ID
=
"
Timer1
"
runat
=
"
server
"
Interval
=
"
1000
"
OnTick
=
"
Timer1_Tick
"
>
19
</
asp:Timer
>
20
</
td
>
21
</
tr
>
22
<
tr
>
23
<
td
>
24
<
asp:Label ID
=
"
Label3
"
runat
=
"
server
"
Text
=
"
Chat Area
"
>
</
asp:Label
>
25
</
td
>
26
</
tr
>
27
<
tr
>
28
<
td
>
29
<
asp:UpdatePanel ID
=
"
UpdatePanel2
"
runat
=
"
server
"
UpdateMode
=
"
Conditional
"
>
30
<
Triggers
>
31
<
asp:AsyncPostBackTrigger ControlID
=
"
Timer2
"
/>
32
</
Triggers
>
33
<
ContentTemplate
>
34
<
asp:TextBox ID
=
"
txMsg
"
runat
=
"
server
"
TextMode
=
"
MultiLine
"
Height
=
"
300
"
Width
=
"
795
"
35
ReadOnly
=
"
true
"
></
asp:TextBox
>
36
</
ContentTemplate
>
37
</
asp:UpdatePanel
>
38
<
asp:Timer ID
=
"
Timer2
"
runat
=
"
server
"
Interval
=
"
1000
"
OnTick
=
"
Timer2_Tick
"
>
39
</
asp:Timer
>
40
</
td
>
41
</
tr
>
42
<
tr
>
43
<
td
>
44
<
asp:TextBox ID
=
"
txSendMsg
"
runat
=
"
server
"
TextMode
=
"
MultiLine
"
Width
=
"
650
"
></
asp:TextBox
>
45
<
asp:Button ID
=
"
btSend
"
runat
=
"
server
"
Text
=
"
Send
"
OnClick
=
"
btSend_Click
"
/>
46
<
asp:Button ID
=
"
btLogOff
"
runat
=
"
server
"
Text
=
"
LogOff
"
OnClick
=
"
btLogoff_Click
"
/>
47
</
td
>
48
</
tr
>
49
</
table
>
其中首先必须有一个ScriptManager控件，并且一个ASPX中只能有一个，然后有两个UpdatePanel块，每块用一个Timer来定时触发异步更新，至于Timer的OnTick响应事件，当然就是设定的时间间隔到了时要做的事情了，这时，就可以异步更新定义在UpdatePanel中的控件内容。这时候，就不会发现页面整个在闪动啦。爽爽爽
另外一种使用ASP.NET AJAX的方式是用WEB SERVICE来响应客户端的异步请求，示例代码如下：
首先，ASPX页面中当然要有ScriptManager块，注意这个块比上面的那种用法多了几行，用标签指示了要请求的服务的路径，指向一个asmx文件。
<asp:ScriptManager ID="ScriptManager1" runat="server" >
<Services>
<asp:ServiceReference Path="~/MyService.asmx" />
</Services>
</asp:ScriptManager>
然后是ASMX中的内容：
[System.Web.Script.Services.ScriptService]
public class MyService : System.Web.Services.WebService {
public MyService () {
//Uncomment the following line if using designed components
//InitializeComponent();
}
[WebMethod]
public string SayHello(string name) {
return "Hello " + name;
}
}
要注意把VS2008自动生成的ASMX中的那行[System.Web.Script.Services.ScriptService]给UNCOMMENT了。
在ASPX页面上有两个HTML 控件：
<input type="text" id="inputName" />
<input type="button" value="Call Service" onclick="return OnButton_Click()" />
并且button控件的响应函数为：
<script type="text/javascript">
function OnButton_Click()
{
requestSimpleService=MyService.SayHello($get('inputName').value,OnRequestComplete);
return false;
}
function OnRequestComplete(result)
{
alert(result);
}
</script>
注意在这儿客户端要运行的脚本中可以直接使用MyService.SayHello函数！！！并且在原先只有的一个参数上，又传递了一个函数名进去，这个函数名指定了当请求结束时，客户端要做什么。这就是框架封装的作用。
现在我使用的是ASP.NET AJAX 3.5，在以往的2007年时代，ASP.NET AJAX 1.0,2.0的时候，使用VS2005开发相关应用，必须先手动安装ASP.NET AJAX组件，然后在WEB.CONFIG中进行配置才可以运行。但现在3.5版本中，ASP.NET AJAX已经被集成为ASP.NET原生应用了，可以直接使用，不城特殊设置！