struts2的<s:textfield>问题

我前台页面：
<script type="text/javascript">
function relation(){
   buttonEnableOrDisabled(true,"button,reset");
   window.location='<%=request.getContextPath()%>/tianqiaouser/tianqiaorelation.action?gongweiuserid=${tpwuser.PUserid}&gongweirgid=${tpwregion.PRgid}';
 }
 </script>
</head> <body onload="">
<s:form action="" name="queryUserSubmit" id="queryUserSubmit">
<table width="100%" cellpadding="0" cellspacing="0" class="AddTable">
<tr>
<td align="center">
请输入需要关联的HIS用户ID:
</td>
<td>
<s:textfield name="hisuserid"></s:textfield>
</td>
</tr>
</table>
</s:form>
</div>

<button onclick="relation();"/>关联</button>
<s:hidden name="hidRegid" id="hidRegid"></s:hidden>
<s:reset cssClass="strutSbutton" value="重置"></s:reset>action中：我定义一个变量private String hisuserid;并且添加了get和set但是 System.out.println(hisuserid);却是空值。我错在了哪里，谢谢！