基本控件

看图

查看网站的验证码的ID

添加MSHTML引用，步骤如下：

完整代码

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Windows.Forms;
using mshtml;


namespace WindowsFormsApp2
{
    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
        }


        private void button1_Click(object sender, EventArgs e)  
        {
            //通过webbrowser控件打开网页
            webBrowser1.Navigate(textBox1.Text.Trim());
            //检查网页是否已经加载完成
            while (webBrowser1.ReadyState < WebBrowserReadyState.Complete)
                Application.DoEvents(); //若没加载完则继续加载

            //根据验证码ID获取验证码元素
            HtmlElement ImageCodeTag = webBrowser1.Document.GetElementById("vcodeimg");

            //调用GetCodeImage方法获取验证码
            Image FinalImage = GetCodeImage(webBrowser1, ImageCodeTag);


            //验证码显示
            pictureBox1.Image = FinalImage;
        }

        /// <summary>
        /// 获取验证码方法
        /// </summary>
        /// <param name="WebControlName"></param>
        /// <param name="ImgeTag"></param>
        /// <returns></returns>
        private Image GetCodeImage(WebBrowser WebControlName, HtmlElement ImgeTag)
        {
            //获取网页所有内容
            HTMLDocument hdoc = (HTMLDocument)WebControlName.Document.DomDocument;
            //获取网页body标签中的内容
            HTMLBody hbody = (HTMLBody)hdoc.body;
            //创建一个接口
            IHTMLControlRange hcr = (IHTMLControlRange)hbody.createControlRange();
            //获取图片地址
            IHTMLControlElement hImg = (IHTMLControlElement)ImgeTag.DomElement;
            //将图片添加到接口中
            hcr.add(hImg);
            //将图片复制到内存
            hcr.execCommand("Copy", false, null);
            //从粘贴板得到图片
            Image CodeImage = Clipboard.GetImage();
            //返回得到的验证码
            return CodeImage;
        }

    }
}