function checklogin(){
			if(document.all.account.value=="")
			{
			  document.all.account.focus();
		 	  return false;
			}
			if(document.all.password.value=="")
			{
			  document.all.password.focus();
		 	  return false;
			}
			var xmlhttp;
			try{
				xmlhttp=new XMLHttpRequest();
				}
			catch(e){
				xmlhttp=new ActiveXObject("Microsoft.XMLHTTP");
				}
			xmlhttp.onreadystatechange=function(){
			document.getElementById('login_1').style.display = "none";
			document.getElementById('login_2').style.display = "";
                        login_2.innerHTML="<img src='http://www.bst120.com/images/loading.gif'> 登录中..."; 
			if (xmlhttp.readyState==4){
				if (xmlhttp.status==200){
					var data=xmlhttp.responseText;
					login.innerHTML=data;
					document.getElementById('login_1').style.display = "none";
					document.getElementById('login_2').style.display = "none";					
					document.getElementById('login').style.display = "";					
					}
				else{
					document.getElementById('login_1').style.display = "none";
					document.getElementById('login_2').style.display = "none";					
				        login.innerHTML="请求超时，点击<a href='' onclick='location.reload();'>刷新</a>"					
				    }
				}
			}			
			xmlhttp.open("post","../login_ajax.asp",true);
			xmlhttp.setRequestHeader('Content-type','application/x-www-form-urlencoded');
			var account=document.all.account.value;
			var password=document.all.password.value;
			var url="account="+account+"&password="+password;
			xmlhttp.send(url)
		}