XMLHttpRequest实现无刷新验证用户名

在用户注册时，我们经常需要检查用户名是否存在，本文就是实现无刷新验证用户名

打开开发环境VS 2005,新建项目(或打开现有项目),新建一个Web窗体,命名为 Default.aspx

代码如下：

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<%@ 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>无标题页</title>
    <script type="text/javascript"></script>
</head>
<body>
    <form id="form1" runat="server">
    用户名:<input type="text" id='txt' value="Sandy" onblur="openAjax();" /> <span id="resultSpan"></span>
    </form>
</body>
</html>
<%@ 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>无标题页</title>
    <script type="text/javascript"></script>
</head>
<body>
    <form id="form1" runat="server">
    用户名:<input type="text" id='txt' value="Sandy" onblur="openAjax();" /> <span id="resultSpan"></span>
    </form>
</body>
</html>

然后新建一个一般处理程序，命名为 VerifyUserNameHandler.ashx

代码如下：

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<%@ WebHandler Language="C#" Class="VerifyUserNameHandler" %>
using System;
using System.Web;
using System.Collections;
using System.Collections.Generic;
public class VerifyUserNameHandler : IHttpHandler {

    public void ProcessRequest (HttpContext context) {
        //context.Response.ContentType = "text/plain";
        string _name = context.Request.QueryString["para"];
        _name = string.IsNullOrEmpty(_name) ? "" : _name;
        System.Threading.Thread.Sleep(3000);//用线程来模拟数据库查询工作
        string[] Names = new string[] { "Sandy", "阿非", "abc" };//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;
        }
    }
}
<%@ WebHandler Language="C#" Class="VerifyUserNameHandler" %>
using System;
using System.Web;
using System.Collections;
using System.Collections.Generic;
public class VerifyUserNameHandler : IHttpHandler {

    public void ProcessRequest (HttpContext context) {
        //context.Response.ContentType = "text/plain";
        string _name = context.Request.QueryString["para"];
        _name = string.IsNullOrEmpty(_name) ? "" : _name;
        System.Threading.Thread.Sleep(3000);//用线程来模拟数据库查询工作
        string[] Names = new string[] { "Sandy", "阿非", "abc" };//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;
        }
    }
}