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 |
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
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