var user_tb='0' ;
function setCookie (name, value) {  //设置名称为name,值为value的Cookie  
	 
        document.cookie = name + "=" + value  ;
		 
}  
function getCookie(name)
{
 
  var cookieValue = "";
  var search = name + "="; 
  if(document.cookie.length > 0)
  { 
    offset = document.cookie.indexOf(search);
    if (offset != -1)
    { 
      offset += search.length;
      end = document.cookie.indexOf(";", offset);
      if (end == -1) end = document.cookie.length;
      cookieValue = document.cookie.substring(offset, end);
     
    }
  }
  return cookieValue;
}
if(islogon){
user_tb=getCookie("user_tb");
if(user_tb==""){  //2009-5-11:设置cookie，如果cookie为空


 
}

}else{
	setCookie("user_tb","");
}