asp.net客户端同步服务端实时刷新时间

 
//首先加入下列脚本
< script > ...
        //获取时间
    function Timer(span)
        ...{
                            var tmp = new Date();
            var milsecs=Date.parse(tmp.getMonth()+"-"+tmp.getDay()+"-"+tmp.getFullYear()+" "+document.getElementById('lbl_Hour').innerText+":"+document.getElementById('lbl_Minute').innerText+":"+document.getElementById('lbl_Second').innerText);
            var timer = new Date(milsecs+span);
            var seconds,minutes,hours;
            if(timer.getSeconds()<10)
                seconds = "0"+timer.getSeconds();
            else
                seconds = timer.getSeconds();
            if(timer.getMinutes()<10)
                minutes = "0"+timer.getMinutes();
            else
                minutes = timer.getMinutes();
            if(timer.getHours()<10)
                hours = "0"+timer.getHours();
            else
                hours = timer.getHours();    
            document.getElementById('lbl_Second').innerText = seconds;
            document.getElementById('lbl_Minute').innerText = minutes;
            document.getElementById('lbl_Hour').innerText = hours;
        }
        //得到服务器时间每隔updatespan分钟校验一次，每秒更新一次本地时钟
        function GetServerTime(updatespan)
        ...{    
            var clientspan = 1*1000;
            //更新本地时钟
            setInterval("Timer("+clientspan+")",clientspan);
            //同步服务器时钟 注意'SendErrorTaskModify.aspx'是你当前页的名称
            setInterval("window.location.href='SendErrorTaskModify.aspx'",updatespan);
            
        }
        //-->
     script >
                     //下面这个方法也可以移到aspx.cs后台文件中
     < script  language ="C#"  runat ="server" > ...
        
        string GetTime(object day)
        ...{
            if(day.ToString()=="")
                return "";
            else
            ...{
                return(DateTime.Parse(day.ToString()).ToShortTimeString());            
            }
        
        }
     script >

//接着在body 中添加如下方法
< body  onload ="GetServerTime(15*60*1000)" >

//在界面中添加如下时间的label
  < tr >
   < td  colspan ="4" >
                   < asp:Label  ID ="lbl_Time"  runat ="server"  Font-Size ="X-Small"  ForeColor ="blue" > asp:Label >
                   < asp:Label  ID ="lbl_Hour"  runat ="server"  Font-Size ="X-Small"  ForeColor ="blue" > Label asp:Label > :
                   < asp:Label  ID ="lbl_Minute"  runat ="server"  Font-Size ="X-Small"  ForeColor ="blue" > Label asp:Label > :
                   < asp:Label  ID ="lbl_Second"  runat ="server"  Font-Size ="X-Small"  ForeColor ="blue" > Label asp:Label >
    td >
    tr >
//在aspx.cs后台代码中PageLoad(...)中添加 这个非常重要
    lbl_Hour.Text = DateTime.Now.Hour.ToString();
        lbl_Minute.Text = DateTime.Now.Minute.ToString();
        lbl_Second.Text = DateTime.Now.Second.ToString();