<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8">
<title>
login
</title>
<script type="text/javascript" src="send.js"></script>
</head>
<body>
<div>
<input type="text" name="UserName" id="UserName" οnblur="usercheck()"> <span id="showerror"></span>
</div>
<input type="password" name="Pwd" id="Pwd">
<button id="login" >登陆</button>
</body>
</html>此代码是html一个简单的登录界面
var http_request=false;
function usercheck()
{
var username=document.getElementById("UserName").value;
if(username=="")
{
var showerror=document.getElementById("showerror");
showerror.innerText="用户名不能为空！";
}
else
{
send_request("server.aspx?username="+username+"&r="+Math.random());
}
}
function send_request(url)
{
http_request=false;
if(window.XMLHttpRequest)
{
http_request=new XMLHttpRequest();
if(http_request.overrideMimeType)
{
http_request.overrideMimeType('text/xml');
}
}
else
if(window.ActiveXObject)
{
try
{
http_request=new ActiveXObject("Msxml2.XMLHTTP");
}
catch(e)
{
try
{
http_request=new ActiveXObject("Msxml2.XMLHTTP");
}
catch(e)
{
}
}
}
if(!http_request)
{
window.alert("错误！");
return false;
}
http_request.onreadystatechange=processRequest;
http_request.open("GET",url,true);
http_request.send(null);
}
function processRequest()
{
if(http_request.readyState==4)
{
if(http_request.status==200)
{
var str=http_request.responseText;
showMsg(str);
}
else
{
alert("有错误！");
}
}
}
function showMsg(str)
{
if(str=="1")
{
document.getElementById("showerror").innerText="";
}
else
if(str=="0")
{
document.getElementById("showerror").innerText="用户名存在！";
}
else
if(str=="2")
{
document.getElementById("showerror").innerText="用户名不能为空！";
}
}此是send.js 里面包含了对用户名的验证
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;
using System.Xml;
public partial class server : System.Web.UI.Page
{
protected void Page_Load(object sender, EventArgs e)
{
string username = Request.QueryString["username"].ToString();
if (username == "")
{
Response.Write("2");
return;
}
else
if (username == "cxw")
{
Response.Write("0");
return;
}
else
{
Response.Write("1");
return;
}
}
}此是.aspx后缀的服务器后台，用此来接受客户端的数据，从而返回数据
