C#使用WebBrowser获取网页验证码图片实例

private void button1_Click(object sender, EventArgs e)
{
    var wb = new WebBrowser();
    wb.Navigate("http://www.jcard.cn/Charge/UCardDirectCharge.aspx?category=AAWYVVWYKV&product=AAWYVVWYKV010CV");
    //等待加载完毕
    while (wb.ReadyState < WebBrowserReadyState.Complete) Application.DoEvents();
    //遍历寻找验证图像所在元素
    foreach (HtmlElement f in wb.Document.Images)
    {
        if (f.GetAttribute("src").ToLower().EndsWith("randomimage.aspx"))
        {
            //将元素绝对定位到页面左上角
            f.Style = "position: absolute; z-index: 9999; top: 0px; left: 0px";
            //抓图
            var b = new Bitmap(f.ClientRectangle.Width, f.ClientRectangle.Height);
            wb.DrawToBitmap(b, new Rectangle(new Point(), f.ClientRectangle.Size));
            pictureBox1.Image = b;
            break;
        }
    }
}