C#中的GetElementsByClassName方法

    public static class Spread
    {
        /// <summary>
        /// 检索指定class的所有HtmlDocument对象
        /// </summary>
        /// <param name="doc"></param>
        /// <param name="className"></param>
        /// <returns></returns>
        public static HtmlElement GetElementsByClassName(this HtmlDocument doc, string className)
        {
            HtmlElementCollection collection = doc.All;
            //HtmlElementCollection collection = doc.Body.All;
            HtmlElement html = doc.CreateElement("");

            foreach (HtmlElement he in collection)
            {
                if (he.GetAttribute("classname") == className)
                {
                    html.AppendChild(he);
                }
            }
            return html;
        }
    }