jsp登入注册程序下载

<%
String userid =request.getParameter("userid");
String password =request.getParameter("password");
if(userid!=null) //如果是登录提交执行下面代码
{
 if(登录成功)
  {
   session.setAttribute("userid",userid); 
   out.println("<script>alert('登录成功，谢谢光临');self.location.href='"+myRedirect.geturl(url)+"';</script>");//转向到首
  }else{
   out.println("<script>alert('用户名或密码错误');history.back();</script>");
  }
}else{//如果不是登录提交显示现面登录界面
%>
<table width="311" height="162" border="0" align="center" cellpadding="0" cellspacing="0">
  <tr>      
    <td width="311" height="162" align="center"> 您还没有登录，请先登录<br>
        <table width="155" border="0" cellpadding="0" cellspacing="5" class="font12">
  <form  name="loginfrm" action="weblogin.jsp" method="post"  id="loginfrm" onSubmit="return checkfrm();">
          <tr> 
            <td width="41" height="33" valign="bottom">帐&nbsp;号：</td>
            <td width="99" valign="bottom"><input name="userid" type="text" class="textstyle" id="userid" size="12" style="height:20"></td>
          </tr>
          <tr> 
            <td>密&nbsp;码：</td>
            <td><input name="password" type="password" class="textstyle" id="password" size="12" style="height:20;width:94"></td>
          </tr>
          <tr align="center" valign="bottom"> 
            <td height="21" colspan="2"> <input type="submit" name="Submit" value="登录">
              &nbsp; <a href="reg.jsp" target="_blank">没有注册</a>&nbsp; </td>