<%@ Page
Language="C#" AutoEventWireup="true" CodeBehind="Default.aspx.cs"
Inherits="CheckUser.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>检查用户名是否存在</title>
<script type="text/javascript">
var xmlHttp = null;
function createXMLHttpRequest() {
if (xmlHttp == null) {
if (window.XMLHttpRequest) {
//Mozilla 浏览器
xmlHttp = new XMLHttpRequest();
} else if (window.ActiveXObject) {
// IE浏览器
try {
xmlHttp = new ActiveXObject("Msxml2.XMLHTTP");
} catch (e) {
try {
xmlHttp = new ActiveXObject("Microsoft.XMLHTTP");
} catch (e) {
//alert(‘创建失败‘);
}
}
}
}
}
function openAjax() {
if (xmlHttp == null) {
createXMLHttpRequest();
if (xmlHttp == null) {
//alert(‘出错‘);
return;
}
}
var val = document.getElementById(‘txt‘).value;
xmlHttp.open("get", "VerifyUserNameHandler.ashx?para=" + val +
"&date=" + new Date(), true);
xmlHttp.onreadystatechange = xmlHttpChange;
xmlHttp.send(null);
document.getElementById(‘resultSpan‘).innerText =
‘正在检查,请稍候...‘;
}
function xmlHttpChange() {
if (xmlHttp.readyState == 4) {
if (xmlHttp.status == 200) {
var res = xmlHttp.responseText;
document.getElementById(‘resultSpan‘).innerText =
res;
if (res == ‘恭喜，用户名可以使用。‘) {
setTimeout("document.getElementById(‘resultSpan‘).innerText=‘‘;",
2000);
}
else if (res == ‘抱歉，用户名已被使用。‘) {
document.getElementById(‘txt‘).focus();
}
}
}
}
</script>
</head>
<body>
<form id="form1" runat="server">
<div>
用户名:<input type="text" id=‘txt‘ value="" onblur="openAjax();"
/>
<span id="resultSpan"></span>
</div>
</form>
</body>
</html>
using System;
using System.Collections.Generic;
using
System.Linq;
using System.Web;
namespace
CheckUser
{
///
<summary>
/// VerifyUserNameHandler
的摘要说明
///
</summary>
public class
VerifyUserNameHandler : IHttpHandler
{
public void
ProcessRequest(HttpContext
context)
{
context.Response.ContentType =
"text/plain";
//context.Response.Write("Hello
World");
string _name =
context.Request.QueryString["para"];
_name = string.IsNullOrEmpty(_name) ? "" :
_name;
System.Threading.Thread.Sleep(500);//用线程来模拟数据库查询工作
string[] Names = new string[] { "pannian", "liupeng", "chenhao"
};//这里用Names数组来代替数据库中的结果集
if (Array.IndexOf<string>(Names, _name) ==
-1)
{
context.Response.Write("恭喜，用户名可以使用。");
}
else
{
context.Response.Write("抱歉，用户名已被使用。");
}
}
public bool
IsReusable
{
get
{
return
false;
}
}
}
}
原文：http://www.cnblogs.com/liupeng61624/p/3663571.html