document.onkeydown   =   function()  
  {  
          var   k   =   window.event.keyCode;  
          if   (k   ==   116 || (window.event.ctrlKey && window.event.keyCode==82))                                       //屏蔽   F5   刷新键  和CTRL+R
          {  
                  window.event.keyCode         =   0;  
                  window.event.returnValue=   false;  
				  chkrefresh();
          } 
  } 

  var refreshtime=5000;//5秒
  
  
  function chkrefresh()
  {
	var oldtime=Cookie.get('refreshtime');
	var nowtime=new Date().getTime();
	oldtime=parseInt(oldtime);
	if(oldtime+refreshtime<nowtime)
	{
		window.location.reload();
		Cookie.set('refreshtime',nowtime);

	}else
	{
		alert("刷新过快，请稍候");
	}
  }
  
  
	var Cookie = 
	{
	     get : function(name)
	     {
	          var value = "";
	          var arr = document.cookie.match(new RegExp("(^| )"+name+"=([^;]*)(;|$)"));
		     if(arr != null) { value=unescape(arr[2]); }
		     return value;
	     },
	     set : function(name,value,days){
	             if(isNaN(days)){
	                     document.cookie=name + "=" + escape(value) + ";";
	             }else{
	                     document.cookie=name + "=" + escape(value) + ";expires="+new Date(new Date().getTime() + days*86400000).toGMTString();
	             }
	     },
	     del : function(name){
	             document.cookie=name + "=;expires="+new Date().toGMTString();
	     }
	}
	
	function $(id)
	{
		return document.getElementById(id);
	}
	

	
	var refreshtime=5000;//5秒
	function chkrefresh()//检测是否刷新过快
	{
		var oldtime=Cookie.get('refreshtime');
		var nowtime=new Date().getTime();
		oldtime=parseInt(oldtime);
		if(oldtime+refreshtime<nowtime)
		{
			window.location.reload();
			Cookie.set('refreshtime',nowtime);
		
		}else
		{
			alert("刷新过快，请稍候");
		}
	}

	function onloadjsp()
	{
    	$("vc_username").value=Cookie.get('name');
    	var time=new Date().getTime();
		Cookie.set('refreshtime',time);
	}
	
	function onchk()
	{
		Cookie.set('name',$("vc_username").value,1);
	}