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
    
      surls = new List
     
      ();            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
      
       ())                        {                            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);        /// 
        /// 获取窗口句柄        /// 
        /// 
            public IntPtr GetWindowHandle()        {            string name = (Environment.CurrentDirectory + "\\chromedriver.exe");            IntPtr hwd = FindWindow(null, name);            return hwd;        }        /// 
        /// 关闭chromedriver窗口        /// 
        public void CloseWindow()        {            try            {                IntPtr hwd = GetWindowHandle();                SendMessage(hwd, 0x10, 0, 0);            }            catch { }        }        /// 
        /// 退出chromedriver        /// 
        /// 
    
             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