程序代码：

<form id="form1" name="login" method="post">
用户名：<input name="user" type="text" id="user" size="15" /><br /><br />
密　码：<input name="pass" type="password"  id="Pass" size="15" />
<br /><br />
<input type="submit" name="submit" value="登录"  /> &nbsp;
<input type="reset" name="submit2" value="取消"  />
</form>

程序代码：

<script language="javascript">
function check()
{
    if(login.user.value == "")
    {
        alert("用户名不能为空");
        login.user.focus();
        return false;
    }
    else {
    if(login.pass.value == "")
    {
    
        alert("密码不能为空");
        login.pass.focus();
        return false;
    }
    else{
    <% 
    sql="select ManagerNo,ManagerPass * from Manager";
    rs=Bean.exeSQL(sql);
    boolean login_ok = false;
    while(rs.next()){
    if((login.user.value=="<%=rs.getString("ManagerNo")%>") && (login.pass.value=="<%=rs.getString("ManagerPass")%>"))
    {
    login_ok = true;
            break;
    } 
    else 
    login_ok = false;
    }%>
    }
    }    
    return true
}
</script>

<form id="form1" name="login" method="post" action="shouye.jsp" onSubmit="return check()">