<%@ Page Language="C#" AutoEventWireup="true" CodeBehind="WebForm5.aspx.cs" Inherits="WebApplication1.WebForm5" %> <!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 runat="server"> <title></title> <script language="javascript" type="text/javascript"> var xmlHttp; //xmlHttpRequest function createXMLHttpRequest() { if (window.ActiveXObject) xmlHttp = new ActiveXObject("Microsoft.XMLHTTP"); //IE else if (window.XMLHttpRequest) xmlHttp = new XMLHttpRequest(); //Firefox } function htmer_loading() { createXMLHttpRequest(); xmlHttp.onreadystatechange = function () { if (xmlHttp.readyState == 4 && xmlHttp.status == 200) //若响应完成,则显示htmer.asp中的内容 document.getElementById("show").innerHTML = xmlHttp.responseText; else //若响应未完成,则显示Loading document.getElementById("show").innerHTML = "Loading......"; } xmlHttp.open("GET", "Handler1.ashx", true); xmlHttp.send(null); } </script></head><body> <form id="form1" runat="server"> <div> <input type="button" value="check ajax" onclick="htmer_loading()" /> </div> <div id="show"> </div> </form></body></html> 耗时请求页面处理Handler1.ashx public class Handler1 : IHttpHandler { public void ProcessRequest(HttpContext context) { context.Response.ContentType = "text/plain"; Thread.Sleep(3000); context.Response.Write("<Br/> test result"); context