本文转载自微信公众号「UP技术控」，可以通过以下二维码关注。转载本文请联系UP技术控公众号。
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
