客户端获取服务器时间倒计时

 倒计时是我们生活中比不可少的，尤其是搞程序开发的，涉及到电子商务的。都有倒计时的这个技术，首先我给大家分享一下我常常用的倒计时吧，

一、 用ajax写倒计时，ajax写倒计时，大家会发现一个确定就是他不停的想服务器发送请求，如果多了的话，就会对服务器施加压力,

大家如果要看看代码，我可以提供个大家参考，这是vs2005里面的，我以前也讲过vs2005怎么利用ajax不用安装，大家也可以去看看vs005不安装ajax一样用ajax ，

这是前面lianxi.aspx里面的，

      <div>
                                                        <asp:ScriptManager ID="sm" runat="server"></asp:ScriptManager>
                                                       
                                                        <asp:UpdatePanel ID="upnl" runat="server">
                                                            <ContentTemplate>
                                                              
                    <p><font>剩余时间:</font><span>00</span>天<asp:Label
                    ID="lblHours" runat="server"></asp:Label>:<asp:Label ID="lblMinutes"
                    runat="server"></asp:Label>:<asp:Label ID="lblSeconds" runat="server"></asp:Label>
                                                            </ContentTemplate>
                                                            <Triggers>
                                                                <asp:AsyncPostBackTrigger ControlID="timer" EventName="Tick" />
                                                            </Triggers>
                                                        </asp:UpdatePanel>
                                                       
                                                       
                                                        <asp:Timer ID="timer" runat="server" Interval="1000" OnTick="Timer_Tick" />
                                                    </div> 

后面lianxi.aspx.cs

 

  protected void Timer_Tick(object sender, EventArgs e)
    {
        CountdownSpan = endTime - DateTime.Now;//这是服务器端得到的生余时间


        if (CountdownSpan.TotalSeconds > 0)
        {
            //  lblDays.Text = CountdownSpan.Days.ToString();
            lblHours.Text = CountdownSpan.Hours < 10 ? "0" + CountdownSpan.Hours.ToString() : CountdownSpan.Hours.ToString();
            lblMinutes.Text = CountdownSpan.Minutes < 10 ? "0" + CountdownSpan.Minutes.ToString() : CountdownSpan.Minutes.ToString();
            lblSeconds.Text = CountdownSpan.Seconds < 10 ? "0" + CountdownSpan.Seconds.ToString() : CountdownSpan.Seconds.ToString();
        }
    }

二、 用js写的时间倒计时

js文件里面的

      function ShowTime() {
            var nowtime=new Date();                                       //客户端的开始时间
            $(".hddTime").each(function() {
            var s = $(this).val();                                                 //得到结束时间
            var d = new Date(Date.parse(s.replace(/-/g, "/")));
            var ticks = parseInt((d.getTime()-nowtime.getTime())/1000);
            var hh = parseInt(ticks/3600);
            var mm = parseInt((ticks%3600)/60);
            var ss = ticks % 60;

            if (isNaN(ss)) {
                ss = 00;
            }
             if (isNaN(mm)) {
                ss = 00;
            }
             if (isNaN(hh)) {
                ss = 00;
            }
            if (hh >= 0) {
                $("#hh").text(hh);
             
            }
            if (mm >= 0) {
               $("#mm").text(mm);
                
            }
            if (ss >= 0) {
               $("#ss").text(ss);
            }
                  
        })
    }

ShowTime()
var sh;
sh=setInterval(ShowTime,1000);

前台调用js

         <div id="zhensale" runat="server">
                                 <input  type="hidden" class="hddTime" id="hddTime" runat="server"/>  //服务器传过来的结束时间。
                          
                                 
                                        <p  id="hh">00
                                        </p>
                                        <span>小时</span>
                                        <p id="mm">00
                                           </p>
                                        <span>分</span>
                                        <p id="ss">00
                                          </p>
                                     
                                        <span class="label">秒</span>
                                    </div>
                               
                            </div>

 

缺点 ：这个时间，由于当前时间是直接获取你自己电脑上的时间，这样的话，会使时间根据你的电脑的时间改动而影响服务器要的结果，这是肯定是不行的。

 

 

三、 第三种，也就是这里面的最重要的一种，首先我们将服务器的剩余时间传到前台客户端。这个，都不用说了撒，肯定很简单的。我这里是把服务器的当前时间和结束时间传过来的，其实都是一样的原理。这样，再你怎么改变你电脑的时间，对他都没有影响了，是不是。

代码参考：

<!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>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<title>倾颜戏羽倒计时</title>
<style type="text/css">
*{margin:0;padding:0;}
#content{width:300px;margin:0 auto;padding:10px;background:#eee;border:1px solid #999;}
#content p span{color:red;font:bold 20px Arial;}
#content p a{font:12px/23px '宋体';color:#888;}
.div1{ display:none;}
</style>
</head><body><div id="content">
<h1>限时抢购啦！</h1>
<p>还剩<span id="times">20小时23分8秒</span></p>
</div>
<input id="endtime" value="2011/4/06 12:20:12" visible="false"/>    //开始时间，我这里写的是死的，你可以从服务处传过来
<input id="startime" value="2011/4/03 12:20:12" visible="false" />  //结束时间也是和开始时间一样的。
<script language="JavaScript">
var endtime= new Date(document.getElementById("endtime").value);
var nowtime= new Date(document.getElementById("startime").value);
 var leftsecond=parseInt((endtime.getTime()-nowtime.getTime())/1000);//把剩余时间转化成秒。
function fresh()
{
            leftsecond--;
            d=parseInt(leftsecond/3600/24);
            h=parseInt((leftsecond/3600)%24);
            m=parseInt((leftsecond/60)%60);
            s=parseInt(leftsecond%60);
        document.getElementById("times").innerHTML=h+"小时"+m+"分"+s+"秒";
        if(leftsecond<=0){
        document.getElementById("times").innerHTML="抢购已结束";
        clearInterval(sh);
        }
}
fresh()
var sh;
sh=setInterval(fresh,1000);
</script>
</body>
</html>