ASP.NET Ajax 2

代码

<%@ Page Language="C#" AutoEventWireup="true"  CodeFile="Default.aspx.cs" Inherits="_Default" %>

<!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>
</head>
<body>
    <script type="text/javascript" language="javascript">
        var xmlHttp = null; //define the xmlHttpRequest
        window.onload = function() {
            loadXmlHttp();
            sendRequest("Welcome.htm");
        }
        //返回不同浏览器的XMLHttpRequest对象
        function loadXmlHttp() {
            if (window.XMLHttpRequest) {
                xmlHttp = new XMLHttpRequest();
            } else if (window.ActiveXObject) {
            try {
                xmlHttp = new ActiveXObject("Microsoft.XMLHTTP"); //IE6,IE5
            } catch (e) { }
            }
        }
        //发送请求
        function sendRequest(url) {
            if (xmlHttp) {
                xmlHttp.open("GET", url, true);
                xmlHttp.onreadystatechange = onCallback; //function
                xmlHttp.setRequestHeader('Content-type', 'application/x-www-form-urlencoded');
                xmlHttp.send(null);
            }
        }
        function onCallback() {
            if (xmlHttp.readyState == 4) {
                if (xmlHttp.status == 200) {
                    var r = document.getElementById('results');
                    r.innerHTML = xmlHttp.responseText;
                } else {
                alert('Error:'+xmlHttp.status);
                }
            }
        }
    </script>
    <form id="form1" runat="server">
    <div>
      <span id="results"></span>
    </div>
    </form>
</body>
</html>