ajax实现登陆限制

发布房源时，如果为未登录用户，提示登录，登录后转到发房源页面

<!-- js_login 开始 -->
<c:if test="${num=='1'}">
<script type="text/javascript" src="../js/jquery.js" ></script>
<script type="text/javascript" src="../js/jquery.simplemodal.js" ></script>
<script>
$(document).ready(function () {
$('#basicModalContent').modal();
});
</script>
<link type="text/css" href="../css/basic.css" rel="stylesheet" media="screen" />
</c:if>
<!-- js_login 结束 -->

<!-- 登录界面 开始 -->
<div id="basicModalContent" style="display:none;">
<html:form action="/login" method="post">
<table class="backgroundtb" align="center">
    <tr class="loggingstyle">
      <td colspan="2">会员登录</td>
      <td align="right">
      <%-- <a onclick="window.opener='anyone';window.close();" title="关闭"> --%>
      <a href="http://www.sina.com/"><img src="../images/shut.gif" /></a>
      &nbsp;&nbsp;</td>
    </tr>
    <tr class="TextBox">
      <td rowspan="4" style="width:32px;">&nbsp;</td>
      <td>用户名：<html:text property="userName" maxlength="31"/></td>
      <td><html:errors property="userName"/></td>    
    </tr>
    <tr class="TextBox">
      <td>密&nbsp;&nbsp;&nbsp;&nbsp;码：<html:password property="password" maxlength="15"/></td>
      <td><html:errors property="password"/></td>
    </tr>
    <tr class="TextBox1">
      <td colspan="2">
  <ul>
          <li><input type="image" src="../images/iconlogging.gif" alt="登录"/></li>
          <li style="padding-top:6px;"><a href="http://login.ilantu.com/registerPage.do">注册</a></li>
      </ul>
      </td>
    </tr>
    </table>
</html:form>
</div>
<!-- 登录界面 结束 -->

<html:form action="" method="">
..................
..................
.....................
</html:form>