背景

 Selenium是一个用于Web应用程序测试的工具。Selenium测试直接运行在浏览器中，就像真正的用户在操作一样。而对于爬虫来说，使用Selenium操控浏览器来爬取网上的数据那么肯定是爬虫中的杀手武器。这里，我将介绍selenium + 谷歌浏览器的一般使用。

需求

在平常的爬虫开发中，有时候网页是一堆js堆起来的代码，涉及很多异步计算，如果是普通的http 控制台请求，那么得到的源文件是一堆js ，需要自己在去组装数据，很费力；但是采用Selenium+ChromeDriver可以达到所见即所得的完美效果。

实现方式

项目结构：为了方便使用，用的winform程序，附nuget包

 以下是form1.cs的代码，这里就只放关键方法代码了。需要安装最新的chrome浏览器+代码中使用的chromedriver是 v2.9.248315

 private void crawlingWebFunc()
        {
            SetText("\r\n开始尝试...");
            List<testfold> surls = new List<testfold>();
            string path = System.Environment.CurrentDirectory + "\\图片url\\";
            DirectoryInfo root = new DirectoryInfo(path);
            DirectoryInfo[] dics = root.GetDirectories();
            foreach (var itemdic in dics)
            {
                string txt = "";
                StreamReader sr = new StreamReader(itemdic.FullName + "\\data.txt");
                while (!sr.EndOfStream)
                {
                    string str = sr.ReadLine();
                    txt += str;// + "\n";
                }
                sr.Close();
                surls.Add(new testfold() { key = itemdic.FullName, picurl = txt });
            }

            ChromeDriverService service = ChromeDriverService.CreateDefaultService(System.Environment.CurrentDirectory);
            //  service.HideCommandPromptWindow = true;

            ChromeOptions options = new ChromeOptions();
            options.AddArguments("--test-type", "--ignore-certificate-errors");
            options.AddArgument("enable-automation");
            //   options.AddArgument("headless");
            //  options.AddArguments("--proxy-server=http://user:password@yourProxyServer.com:8080");

            using (IWebDriver driver = new OpenQA.Selenium.Chrome.ChromeDriver(service, options, TimeSpan.FromSeconds(120)))
            {
                driver.Url = "https://www.1688.com/";
                Thread.Sleep(200);
                try
                {
                    int a = 1;
                    foreach (var itemsurls in surls)
                    {
                        SetText("\r\n第" + a.ToString() + "个");
                        driver.Navigate().GoToUrl(itemsurls.picurl);
                        //登录
                        if (driver.Url.Contains("login.1688.com"))
                        {
                            SetText("\r\n需要登录，开始尝试...");
                            trylogin(driver); //尝试登录完成
                                              //再试试
                            driver.Navigate().GoToUrl("https://s.1688.com/youyuan/index.htm?tab=imageSearch&imageType=oss&imageAddress=cbuimgsearch/eWXC7XHHPN1607529600000&spm=");

                            if (driver.Url.Contains("login.1688.com"))
                            {
                                //没办法退出
                                SetText("\r\n退出，换ip重试...");
                                return;
                            }
                        }

                        //鼠标放上去的内容因为页面自带只能显示一个的原因 没办法做到全部显示 然后在下载 只能是其他方式下载
                        //  var elements = document.getElementsByClassName('hover-container');
                        //  Array.prototype.forEach.call(elements, function(element) {
                        //  element.style.display = "block";
                        //   console.log(element);
                        //  });

                        //   IJavaScriptExecutor js = (IJavaScriptExecutor)driver;

                        //    var sss = js.ExecuteScript(" var elements = document.getElementsByClassName('hover-container');  Array.prototype.forEach.call(elements, function(element) {  console.log(element); element.setAttribute(\"class\", \"测试title\");  element.style.display = \"block\";  console.log(element); });");

                        Thread.Sleep(500);
                        var responseModel = Write(itemsurls.key, driver.PageSource, Pagetypeenum.列表);
                        Thread.Sleep(500);
                        int i = 1;
                        foreach (var offer in responseModel?.data?.offerList ?? new List<OfferItemModel>())
                        {
                            driver.Navigate().GoToUrl(offer.information.detailUrl);
                            string responseDatadetail = driver.PageSource;
                            Write(itemsurls.key, driver.PageSource, Pagetypeenum.详情);
                            SetText("\r\n第" + a.ToString() + "-" + i.ToString() + "个");
                            Thread.Sleep(500);
                            i++;
                        }
                    }
                }
                catch (Exception ex)
                {
                    CloseChromeDriver(driver);
                    throw;
                }
            }
        }
 　

  #region 异常  退出chromedriver

        [DllImport("user32.dll", EntryPoint = "FindWindow")]
        private extern static IntPtr FindWindow(string lpClassName, string lpWindowName);

        [DllImport("user32.dll", EntryPoint = "SendMessage")]
        public static extern int SendMessage(IntPtr hWnd, int Msg, int wParam, int lParam);

        public const int SW_HIDE = 0;
        public const int SW_SHOW = 5;

        [DllImport("user32.dll", EntryPoint = "ShowWindow")]
        public static extern int ShowWindow(IntPtr hwnd, int nCmdShow);

        /// <summary>
        /// 获取窗口句柄
        /// </summary>
        /// <returns></returns>
        public IntPtr GetWindowHandle()
        {
            string name = (Environment.CurrentDirectory + "\\chromedriver.exe");
            IntPtr hwd = FindWindow(null, name);
            return hwd;
        }

        /// <summary>
        /// 关闭chromedriver窗口
        /// </summary>
        public void CloseWindow()
        {
            try
            {
                IntPtr hwd = GetWindowHandle();
                SendMessage(hwd, 0x10, 0, 0);
            }
            catch { }
        }

        /// <summary>
        /// 退出chromedriver
        /// </summary>
        /// <param name="driver"></param>
        public void CloseChromeDriver(IWebDriver driver)
        {
            try
            {
                driver.Quit();
                driver.Dispose();
            }
            catch { }
            CloseWindow();
        }

        #endregion 异常  退出chromedriver

　效果

总结

说一下思路:

1.跳转到指定的网页driver.Navigate().GoToUrl

2.确定数据源，从driver.PageSource读取数据

3.对html数据进行解析