通过获取一次服务器时间动态添加服务器时间

<%@ page language="java" import="java.util.*" pageEncoding="ISO-8859-1"%>
<%
String path = request.getContextPath();
String basePath = request.getScheme()+"://"+request.getServerName()+":"+request.getServerPort()+path+"/";
%>

<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
<head>
    <base href="<%=basePath%>">

    <title>My JSP 'index.jsp' starting page</title>
<meta http-equiv="pragma" content="no-cache">
<meta http-equiv="cache-control" content="no-cache">
<meta http-equiv="expires" content="0">
<meta http-equiv="keywords" content="keyword1,keyword2,keyword3">
<meta http-equiv="description" content="This is my page">

<script type="text/javascript">
function dateDiff(interval, date1, date2)
    {
        var objInterval = {'D' : 1000 * 60 * 60 * 24, 'H' : 1000 * 60 * 60, 'M' : 1000 * 60, 'S' : 1000, 'T' : 1};
        interval = interval.toUpperCase();
        var dt1 = Date.parse(date1.replace(/-/g, '/'));
        var dt2 = Date.parse(date2.replace(/-/g, '/'));
        try
        {
            return Math.round((dt2 - dt1));
        }
        catch (e)
        {
            return e.message;
        }
    }

function getClientDate()
{
  var myDate=new Date();
  var year=myDate.getYear();
  var month=myDate.getMonth();
  var date=myDate.getDate();
  var hour=myDate.getHours();
  var mininute=myDate.getMinutes();
  var second=myDate.getSeconds();
  var timestr=year+"-"+(month+1)+"-"+date+" "+hour+":"+mininute+":"+second;
  return timestr;

}
var cha=0;
function init()
{
  var server=document.getElementById("datestr").value;
  var client=getClientDate();
  cha=Math.abs(dateDiff("s",server,client));
  alert(cha);
  startTime();
}


function startTime(){
    var mei = new Date();
    var y = mei.getYear();
    var m = mei.getMonth();
    var d = (mei.getDate()   > 9) ? mei.getDate()   : "0" + mei.getDate();
    mei.setTime(mei.getTime() + cha);
    var h = (mei.getHours()   > 9) ? mei.getHours()   : "0" + mei.getHours();
    var mi = (mei.getMinutes() > 9) ? mei.getMinutes() : "0" + mei.getMinutes();
    var s = (mei.getSeconds() > 9) ? mei.getSeconds() : "0" + mei.getSeconds();
    document.getElementById("clock").innerHTML = y+"-"+(m+1)+"-"+d+" "+ h +":"+ mi +":"+ s;
    setTimeout("startTime()", 1000);
}
</script>
</head>

<body>
    This is my JSP page. <br>
    <input id="datestr" type="hidden" value="<%new Date().toLocaleString() %>>">
    <span id="clock">fgfg</span>
</body>
<script type="text/javascript">
init();
</script>
</html>