关于在后台如何遍历前台的DIV

关于在后台怎么遍历前台的DIV
<form id="form1" runat="server">
  <div runat="server">
  </div>
   
  <div runat="server">
  </div>

   
  <div runat="server">
  </div>
  </form>
在后台用foreach怎么遍历前台的所有DIV

  foreach (Control item in form1.Controls)
  { 
  item as 什么
  }


[解决办法]
as System.Web.UI.HtmlControls.HtmlGenericControl