一 環境
Asp.net 2.0
VS 2005
二 客戶端
<%@ Page Language="C#" AutoEventWireup="true" CodeFile="ajaxnet.aspx.cs" Inherits="ajaxnet" %><!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"><html xmlns="http://www.w3.org/1999/xhtml" > <head> <title>Server Time</title> <script type="text/javascript" language="javascript"> function GetServerTime() 
{ 
var message = ''; var context = ''; <%=sCallBackFunctionInvocation%> 
} function ShowServerTime(timeMessage, context) { var a = document.getElementById("loadinfo"); a.innerHTML = timeMessage; } </script> </head> <body> <form id="MainForm" runat="server"> <input id="button1" type="button" value="得到服務器端時間" onclick="GetServerTime();" /> </form> <div id="loadinfo"></div> </body> </html> 三 後端代碼：
using System;using System.Data;using System.Configuration;using System.Collections;using System.Web;using System.Web.Security;using System.Web.UI;using System.Web.UI.WebControls;using System.Web.UI.WebControls.WebParts;using System.Web.UI.HtmlControls;public partial class ajaxnet : System.Web.UI.Page,ICallbackEventHandler{ public string sCallBackFunctionInvocation; void Page_Load(object sender, System.EventArgs e)
{
sCallBackFunctionInvocation = Page.ClientScript.GetCallbackEventReference(this, "message", "ShowServerTime", "context");
} public void RaiseCallbackEvent(string eventArgument) { } public string GetCallbackResult() { System.Threading.Thread.Sleep(2000); return DateTime.Now.ToString(); }}必須繼承ICallbackEventHandler接口，實現GetCallbackResult()
方法來返回值。
GetCallbackEventReference:獲取一個對客戶端函數的引用；調用該函數時，將啓動一個對服務器端事件的客戶端回調。此重載方法的客戶端函數包含指定的控件、參數、客戶端腳本和上下文。