function Set_cookie(key,obj,time){
var Today=new Date();
var tt
var expireDay=new Date()
switch(time){
case 0:tt=0;break;//立即过期
case 1:tt=24*60*60*1000;break;//日
case 2:tt=24*60*60*1000*31;break;//月
case 3:tt=24*60*60*1000*31*12;break;//年
case 4:tt=100000000000;break;//相对的无限
default :tt=24*60*60*1000}
expireDay.setTime(Today.getTime()+tt);
document.cookie=escape(key)+"="+escape(obj)+";expires="+expireDay.toGMTString();//写入cookies
}


function Get_cookie(key){
var Today=new Date();
var key=key+"=";
var N1=document.cookie.indexOf(key)
if(N1<0) return null
else {
var N2=document.cookie.indexOf(";",N1)
N2>0?N2=document.cookie.indexOf(";",N1):N2=document.cookie.length
return document.cookie.slice(N1+key.length,N2)}
}


function Del_cookie(key){
var Today=new Date();
document.cookie=key+"=;expires="+Today.toGMTString()
}