简单验证码识别及登陆并下载页面

1-背景

   公司需要做一个抓取功能，抓取网站需要登录才可以抓取，登录有验证码，所以就有了该需求

2-实现

   百度了好久，找到了OCR图文识别库，不过该库是C++编写，不过有一个.NET封装版本 ，那我们就开始折腾吧

2.1 分析网站获取验证码图片

    a-通过查看网页源码可以看见，与登陆有关的js 是new_login.min.js,我们把它下载下来，然后格式化查看就得到了，验证码获取方法和验证码校验方法以及登录方法

验证码获取方法

验证码校验方法

登录方法

 其实通过找个代码可以看出我们其实可以绕过验证码，直接登录的。

 2.2 接下来我们开始分析验证码，并且校验

   安装OCR .net封装版本

2.3 识别验证码，单生成的验证码图片中的字符挨得比较近的时候，识别率很低

            var imgurl = string.Format("https://www.XXXX.cn/cblcn/member.login/captcha?t={0}&randomID={1}", timeTicks, randomNum);
       
            var uir = new Uri(imgurl);
            var imgByte = webClient.DownloadData(uir);
            var imgStream = new MemoryStream(imgByte);
            var image = new Bitmap(imgStream);
            //省略了识别
            if (string.IsNullOrEmpty(result.VCode))
                new Bitmap(imgStream).Save(Path.Combine(AppDomain.CurrentDomain.BaseDirectory, string.Format("{0}.png", Guid.NewGuid().ToString().ToLower().Replace("-", ""))));
            else
                new Bitmap(imgStream).Save(Path.Combine(AppDomain.CurrentDomain.BaseDirectory, string.Format("{0}.png", result.VCode)));
            return result;

 /// <summary>
        /// 识别图片，返回验证码
        /// </summary>
        /// <param name="image"></param>
        /// <returns></returns>
        public static string StartOCR(Bitmap image)
        {
            string defaultList = "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz";
            //string defaultList = "2345689ABCDEFGHJKLMNPRSTWXY";
            const string language = "eng";

            //Nuget安装的Tessract版本为3.20，tessdata的版本必须与其匹配，另外路径最后必须以""或者"/"结尾
            const string TessractData = @"D:workhaoBiaoSolutionYanZhengMaDemo	essdata";

            TesseractEngine test = new TesseractEngine(TessractData, language);

            test.SetVariable("tessedit_char_whitelist", defaultList);


            var tmpPage = test.Process(image, pageSegMode: test.DefaultPageSegMode);

            return tmpPage.GetText();
        }

        /// <summary>
        /// 获取验证码
        /// </summary>
        /// <param name="randomNum"></param>
        /// <param name="timeTicks"></param>
        /// <returns></returns>
        public static VerificationCodeRequest GetVerificationCode(WebClient webClient, string randomNum, long timeTicks)
        {
            var result = new VerificationCodeRequest();
            var imgurl = string.Format("https://www.chinabidding.cn/cblcn/member.login/captcha?t={0}&randomID={1}", timeTicks, randomNum);
            //string defaultList = "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz";
            var uir = new Uri(imgurl);
            var imgByte = webClient.DownloadData(uir);
            var imgStream = new MemoryStream(imgByte);
            var image = new Bitmap(imgStream);
            result.VCode = StartOCR(image).Trim();
            result.TimeTicks = timeTicks;
            result.RandomNum = randomNum;
            //while (string.IsNullOrEmpty(result.VCode) && result.VCode.Length < 4)
            //{
            //    result = GetVerificationCode(webClient, randomNum, GetJsTimeTicks());
            //}
            if (string.IsNullOrEmpty(result.VCode))
                new Bitmap(imgStream).Save(Path.Combine(AppDomain.CurrentDomain.BaseDirectory, string.Format("{0}.png", Guid.NewGuid().ToString().ToLower().Replace("-", ""))));
            else
                new Bitmap(imgStream).Save(Path.Combine(AppDomain.CurrentDomain.BaseDirectory, string.Format("{0}.png", result.VCode)));
            return result;
        }

2.4 获取到了验证码后，我们就开始校验验证码，该方法使用了RestSharp

 private const string _domainUrl = "https://www.xxxxx.cn";
        /// <summary>
        /// 校验验证码
        /// </summary>
        /// <returns></returns>
        public static string CheckVerificationCode(VerificationCodeRequest data)
        {
            //验证
            var action = "/cblcn/member.login/checkyzm";
            var client = new RestClient(_domainUrl);
            var request = new RestRequest(action, Method.POST);
            request.AddParameter("randomID", data.RandomNum);
            request.AddParameter("yzm", data.VCode);
            request.AddParameter("t", data.TimeTicks);
            //
            request.AddHeader("Accept", "text/html");
            var result = client.Execute(request);
            return result.Content;
        }

 2.5 接下来就是登录了，返回的是IRestResponse对象，因为我需要里面的登录返回结果以及服务器cookies

 /// <summary>
        /// 登录
        /// </summary>
        /// <returns></returns>
        public static IRestResponse Login()
        {
            //验证
            var action = "/cblcn/member.login/logincheck";
            var client = new RestClient(_domainUrl);
            var request = new RestRequest(action, Method.POST);
            request.AddParameter("name", "name");
            request.AddParameter("password", "密码");
            request.AddParameter("url", "");
            //
            request.AddHeader("Accept", "text/html");
            var result = client.Execute(request);
            return result;
        }

2.6 最后带着cookies 访问需要的页面并且下载页面数据

        public static string GetPageHtml(string url, IList<RestResponseCookie> cookies)
        {
            //var action = "/zbgs/eofTK.html";
            var client = new RestClient(_domainUrl);
            var request = new RestRequest(url, Method.POST);
            if (cookies != null)
            {
                client.CookieContainer = new CookieContainer();
                foreach (var cookie in cookies)
                {
                    client.CookieContainer.Add(new Cookie(cookie.Name, cookie.Value, cookie.Path, cookie.Domain));
                }
            }
            //client.DownloadData(request);
            var response= client.Execute(request);
            
            return response.Content;
        }

打完收工

 2.7 正则获取数据

//登录
            //zbgg/eoyHX.html#pos_60117326
            var html = VerificationCodeUtils.GetPageHtml("/zbgs/eofTK.html", Method.GET, lresult.Cookies);
            // Console.WriteLine(html);
            var matchCollection = new Regex("<div class="cen_xq c_xq_b(?<content>.*?)<div class="anniu1">", RegexOptions.IgnoreCase | RegexOptions.Singleline | RegexOptions.ExplicitCapture).Matches(html);//new Regex("<div class="cen_xq c_xq_b" id="(?<id>.*?)">(?<content>.*?)<div class="anniu1">", RegexOptions.IgnoreCase | RegexOptions.Singleline | RegexOptions.ExplicitCapture).Matches(html);
            foreach (Match match in matchCollection)
            {
                //Console.WriteLine(match.Value);
            }
            Console.WriteLine("--------------------------------------------------------");
            Console.WriteLine();
             var html2 = VerificationCodeUtils.GetPageHtml("/search/searchgj/zbcg", Method.GET, lresult.Cookies);
           
            var matchCollection2 = new Regex("bordercolordark="WHITE">-->(?<content>.*?)</table>", RegexOptions.IgnoreCase | RegexOptions.Singleline | RegexOptions.ExplicitCapture).Matches(html2);
            foreach (Match match in matchCollection2)
            {
                Console.WriteLine(match.Value);
            }

参考文章：

https://www.cnblogs.com/warioland/archive/2012/03/06/2381355.html

https://www.cnblogs.com/lcawen/articles/7040005.html

http://www.cnblogs.com/ivanyb/archive/2011/11/25/2262964.html

http://www.cnblogs.com/263613093/p/5076146.html