DataList 外部事件获取DataList内部值

//外部事件

        protected void OK_Click(object sender, ImageClickEventArgs e)
        {
            foreach (DataListItem item in RoomList.Items)
            {
                if (item.ItemType == ListItemType.Item || item.ItemType == ListItemType.AlternatingItem || item.ItemType == ListItemType.EditItem)
                {
                 
                    TextBox txt = (TextBox)item.FindControl("RoomNum");
                    string str = txt.Text;
                    Response.Write("<script>alert('"+str.ToString()+"')</script>");
                }
            }

        }