em có 1 doan code nhưng k biet cach sua no , mong các anh chị sửa dùm em với T_T
em bi sai o câu String userid= getVal((String)session.getValue("userid"),"");
thank mọi người


<%@page contentType="text/html" pageEncoding="UTF-8"%>
<!DOCTYPE html>
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<title>JSP Page</title>
</head>
<body>
<script language="JavaScript">
function checkinput(){
if(document.form1.username.value==""){
alert("Xin vui long nhap username");
document.form1.username.focus();
return false;
}
if(document.form1.password.value=="" ){
alert("Xin vui long nhap password");
document.form1.password.focus();
return false;
}
return true;
}
</script>
<%
String userid= getVal((String)session.getValue("userid"),"");
String err="Xin vui loøng nhaäp username vaø password";
if(userid.equals("0")){
err="<font color=\"#FF0000\">Sai password,Xin vui lòng nhaäp password</font>";}
if(userid.equals("-1")){
err="<font color=\"#FF0000\">Sai username,Xin vui lòng nhaäp username</font>";}
if(userid.equals("-2")){
err="<font color=\"#FF0000\">Loãi heä thoáng, Xin vui loøng thöû laïi</font>";}
%>
<form action=login_authentication.jsp name=form1 method=post onSubmit="return checkinput();">
<table align=center>
<tr>
<td colspan="2" height="19">
<h4><font color="#FF0000">
Nhaân vieân quaûn lyù
</font></h4><hr></td>
</tr>
<tr>
<td colspan=2 height="19">
<div align="left"></div></td>
</tr>
<tr>
<td height="19">
<div align="left">Username</div></td>
<td height="19">
<div align="left">
<input type="text" name="username" size="30" maxlength="50" </tr>
<tr>
<td height="31">
<div align="left">Password</div></td>
<td height="31">
<div align="left">
<input type="password" name="password" size="30" maxlength="10" </tr>
<tr>
<td > </td>
<td> </td>
</tr>
<tr>
<td ></td>
<td ><input type=submit value="Ñaêng nhaäp">
<input type=reset value=Huyû></td>
</tr>
</table>
</form>
</body>
</html>