Webbrowser获取<button>标签的class的值

<pre name="code" class="csharp">//测试按钮        private void button2_Click(object sender, EventArgs e)        {            try            {                HtmlElementCollection Input = webBrowser1.Document.GetElementsByTagName("button");                HtmlElementCollection Button = webBrowser1.Document.GetElementsByTagName("button");                foreach (HtmlElement btn in Button)                {                    if (btn.GetAttribute("className").Equals("123")) //这里当<button class="123" >的class="123"时                    {                        //去执行。。。。。                        break;                    }                }            }            catch (Exception ex)            {                MessageBox.Show("结果："+ex);            }<span style="white-space:pre"></span>}