验证用户名是否有重复的代码

 

客户端：

    function ValidateUser()
    {
        //alert("hello");
        var obj = document.getElementById("lblCheckUser");
        var account = document.getElementById("txtAccount").value;
        if(account.length < 3)
        {
            obj.innerHTML = '<span style="vertical-align:middle; text-align:center"><img src="../images/check_error.gif" width="12" height="12"> ' + "对不起，您输入的帐号小于3个字符, 请输入一个较长的用户名。</span>";
            return;
        }
        var chk = true;
        
        if(chk) {
            var username = escape(account);
            var url = "CheckUser.aspx?name=" + account + "&t=" + Math.random(); //加参数t是为了保证URL不同（防止两次传的URL一样，js就不会从数据库中查找，直接从缓存中查找）
            //alert(url);
            var sta = GetResponseText(url); 
            //alert(sta);
            
            //异步传输失败
            if(sta == false) 
            {
                chk = true;
                obj.className = "d_ok";
                obj.innerHTML = '未能检测注册，可以尝试注册！';
             }//if(sta == false)
             //异步传输成功
             else 
             {
                if(sta.indexOf("regok") != -1) 
                {
                    //验证通过
                    chk = true;
                    obj.className = "Right";
                    obj.innerHTML =  '<span style="vertical-align:middle; text-align:center"><img src="../images/check_right.gif" width="12" height="12"> ' + "该帐号可以注册！</span>";;
                   
                 }
                 else
                 {
                    chk = false;
                    obj.className = "Error";
                    obj.innerHTML = '<span style="vertical-align:middle; text-align:center"><img src="../images/check_error.gif" width="12" height="12"> ' + "该帐号已经被注册，请改名后重试！</span>";
                  } 
              }// else         
          }// if(chk)
          else
          {
            obj.className = "Error";
          }//end else       
          return chk;
    }

    function GetResponseText(url)
    {
        var http_request;
    //获取XMLHttpRequest对象
        if(window.XMLHttpRequest)
        {
            http_request = new XMLHttpRequest();
            if(http_request.overrideMimeType)
            {
                http_request.overrideMimeType('text/xml');
            }
        }//if(window.XMLHttpRequest)
        else if (window.ActiveXObject)
        {
            try
            {
                http_request = new ActiveXObject("Msxml2.XMLHTTP");
            }
            catch (e)
            {
                try
                {
                    http_request = new ActiveXObject("Microsoft.XMLHTTP");
                }
                catch(e)
                {
                }
            }
        }//else if (window.ActiveXObject)
        
    //发送请求
        http_request.open('GET', url, false);
        http_request.send(null);
        if(http_request.readyState == 4)
        {
            if(http_request.status == 200)
            {
                var requestdoc = http_request.ResponseText;
            }
            else
            {
                requestdoc = "error";
            }
        }
        
        return requestdoc;
        
    }//end GetResponseText(url)

服务端代码：

        string nam = Request.QueryString["name"].ToString(); //获取URL中name参数值
        BLAdmin admin = DalFactory.Factory.GetBLAdmin();
        bool isExist = admin.hasSameName(nam); //查找数据库中是否有相同的用户名
        if (isExist)
        {
            Response.Write("Error");
        }
        else
        {
            Response.Write("regok");
        }