multipart/form-data 获取不到hidden数据

<input type="button" value="提交" onclick="javascript:changeSubmitUrl();" />  <input type="reset" value="重置"/>  <input type="button" value="取消" onClick="javascript:window.history.go(-1);"/><br/>  </form>  <c:set var="method" value="${mark=='新增'?'addBook':'editBook' }"></c:set>  <script type="text/javascript">  function changeSubmitUrl(){document.form1.action=document.form1.action+"?method=${method }";document.form1.submit();  }  </script>

传送门：http://blog.csdn.net/hurryjiang/article/details/7549768