java.text.SimpleDateFormat simpleDateFormat = new java.text.SimpleDateFormat( 
   "yyyy-MM-dd HH:mm:ss"); 
  java.util.Date currentTime = new java.util.Date(); 
  String time = simpleDateFormat.format(currentTime).toString();  //放到页面的head中} 

function showtime() 
{ 
var today;
var hour;
var second;
var minute;
var year;
var month;
var date;
var strDate; 
today=new Date(); 
var n_day = today.getDay(); 
switch (n_day) 
{ 
case 0:{ 
strDate = "星期日" 
}break; 
case 1:{ 
strDate = "星期一" 
}break; 
case 2:{ 
strDate ="星期二" 
}break; 
case 3:{ 
strDate = "星期三" 
}break; 
case 4:{ 
strDate = "星期四" 
}break; 
case 5:{ 
strDate = "星期五" 
}break; 
case 6:{ 
strDate = "星期六" 
}break; 
case 7:{ 
strDate = "星期日" 
}break; 
} 
year = today.getYear(); 
month = today.getMonth()+1; 
date = today.getDate(); 
hour = today.getHours(); 
minute =today.getMinutes(); 
second = today.getSeconds(); 
if(month<10) month="0"+month; 
if(date<10) date="0"+date; 
if(hour<10) hour="0"+hour; 
if(minute<10) minute="0"+minute; 
if(second<10) second="0"+second; 
document.getElementById('clock').innerHTML = year + "年" + month + "月" + date + "日 " + strDate +" " + hour + ":" + minute + ":" + second; 
setTimeout("showtime();", 1000); 
}