我怎样才能在HttpModules中根据不同的角色控制页面中Repeater控件按钮的可用性

这下面是我写的一些代码，这只能控制repeater控件外面的，请大家帮帮忙，怎样才能控件里面的，急急急急急
 public void Init(HttpApplication context)
    {
        context.PreRequestHandlerExecute += new EventHandler(context_PreRequestHandlerExecute);
    }    void context_PreRequestHandlerExecute(object sender, EventArgs e)
    {
        HttpApplication app = (HttpApplication)sender;
        if (app.Context.Request.Url.ToString().ToLower().Contains(".aspx"))
        {
            if (!app.Context.Request.Url.ToString().ToLower().Contains("login.aspx"))
            {
                if (app.Context.Session["currentStationId"] != null)
                {
                    //得到登录用户的岗位
                    int stationId = Convert.ToInt32(app.Context.Session["currentStationId"].ToString());                    //得到登录岗位的权限列表
                    IList<Privilege> priList = PrivilegeManage.GetPrivilegeBySId(stationId);                    bool flag = false;                    foreach (Privilege item in priList)
                    {
                        string pageUrl = item.Module.PageUrl.ToLower();                        if (app.Context.Request.Url.ToString().ToLower().Contains(pageUrl))
                        {
                            flag = true;
                            break;
                        }
                    }                    if (!flag)
                    {
                        app.Context.Response.Redirect("~/Login.aspx");
                    }                }
                //else
                //{
                //    app.Context.Response.Redirect("~/Login.aspx");                //}
            }        }        System.Web.UI.Page page = (System.Web.UI.Page)app.Context.CurrentHandler;
        if (page != null)
        {
            page.PreRender += new EventHandler(page_PreRender);
        }
    }    void page_PreRender(object sender, EventArgs e)
    {
        //获取页面
        HtmlForm form = ((Page)sender).Form;        //循环遍历页面中的控件
        foreach (Control ctl in form.Controls)
        {
            //判断页面中是否有Repeater控件
            //有则遍历Repeater每一行，找到按钮，禁用
            if (ctl.GetType().ToString() == "System.Web.UI.WebControls.Repeater")
            {
                Repeater rpt = ctl as Repeater;
                foreach (Control var in rpt.Items)
                {
                    if (var.GetType().ToString() == "System.Web.UI.WebControls.ImageButton")
                    {
                        ImageButton imgbtn = (ImageButton)var;
                        if(imgbtn.ID.Contains("Delete"))
                        {
                            imgbtn.Enabled = false;
                        }
                    }                    if (var.GetType().ToString() == "System.Web.UI.WebControls.LinkButton")
                    {
                        LinkButton lkbtn = (LinkButton)var;
                        if (lkbtn.ID.Contains("Delete"))
                        {
                            lkbtn.Enabled = false;
                            
                        }
                    }
                    
                }            }
            if (ctl.GetType().ToString() == "System.Web.UI.WebControls.LinkButton")
            {                LinkButton imgbtn = (LinkButton)ctl;
                if (imgbtn.ID.Contains("Delete"))
                {
                    imgbtn.Enabled = false;
                }
            } 
        }
    }