c# 使用 HttpWebRequest模拟登陆（附带验证码）

在C#中，可以使用HttpWebRequest进行相关的模拟登陆，登陆后进行相关的操作，比如抓取数据，页面分析，制作相关登陆助手等等。

先说下流程

1.使用httpwebrequest先进入你要登录的网站，获取cookie

2.使用第一步获取的cookie到验证码的网页将验证码下载下来。

3.使用Post数据 发送至网站。如果有cookie则继续保存。

4.使用第三步的cookie登陆相关网页操作。

获取相关数据可以使用抓包工具进行抓取，如httpwatch。（网上下载的好多都有病毒，下载的时候注意点）

1。

/// <summary>
/// 通过get方式请求页面，传递一个实例化的cookieContainer
/// </summary>
/// <param name="postUrl"></param>
/// <param name="cookie"></param>
/// <returns></returns>
public static ArrayList GetHtmlData(string postUrl, CookieContainer cookie)
{
    HttpWebRequest request;
    HttpWebResponse response;
    ArrayList list = new ArrayList();
    request = WebRequest.Create(postUrl) as HttpWebRequest;
    request.Method = "GET";
    request.UserAgent = "Mozilla/4.0";
    request.CookieContainer = cookie;
    request.KeepAlive = true;

    request.CookieContainer = cookie;
    try
    {
        //获取服务器返回的资源
        using (response = (HttpWebResponse)request.GetResponse())
        {
            using (StreamReader reader = new StreamReader(response.GetResponseStream(), Encoding.Default))
            {
                cookie.Add(response.Cookies);
                //保存Cookies
                list.Add(cookie);
                list.Add(reader.ReadToEnd());
                list.Add(Guid.NewGuid().ToString());//图片名
            }
        }
    }
    catch (WebException ex)
    {
        list.Clear();
        list.Add("发生异常/n/r");
        WebResponse wr = ex.Response;
        using (Stream st = wr.GetResponseStream())
        {
            using (StreamReader sr = new StreamReader(st, System.Text.Encoding.Default))
            {
                list.Add(sr.ReadToEnd());
            }
        }
    }
    catch (Exception ex)
    {
        list.Clear();
        list.Add("5");
        list.Add("发生异常：" + ex.Message);
    }
    return list;
}

2.下载验证码，保存在本地。

/// <summary>
        /// 下载验证码图片并保存到本地
        /// </summary>
        /// <param name="Url">验证码URL</param>
        /// <param name="cookCon">Cookies值</param>
        /// <param name="savePath">保存位置/文件名</param>
        public static bool DowloadCheckImg(string Url, CookieContainer cookCon, string savePath)
        {
            bool bol = true;
            HttpWebRequest webRequest = (HttpWebRequest)WebRequest.Create(Url);
            //属性配置
            webRequest.AllowWriteStreamBuffering = true;
            webRequest.Credentials = System.Net.CredentialCache.DefaultCredentials;
            webRequest.MaximumResponseHeadersLength = -1;
            webRequest.Accept = "image/gif, image/x-xbitmap, image/jpeg, image/pjpeg, application/x-shockwave-flash, application/vnd.ms-excel, application/vnd.ms-powerpoint, application/msword, */*";
            webRequest.UserAgent = "Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.1; SV1; Maxthon; .NET CLR 1.1.4322)";
            webRequest.ContentType = "application/x-www-form-urlencoded";
            webRequest.Method = "GET";
            webRequest.Headers.Add("Accept-Language", "zh-cn");
            webRequest.Headers.Add("Accept-Encoding", "gzip,deflate");
            webRequest.KeepAlive = true;
            webRequest.CookieContainer = cookCon;
            try
            {
                //获取服务器返回的资源
                using (HttpWebResponse webResponse = (HttpWebResponse)webRequest.GetResponse())
                {
                    using (Stream sream = webResponse.GetResponseStream())
                    {
                        List<byte> list = new List<byte>();
                        while (true)
                        {
                            int data = sream.ReadByte();
                            if (data == -1)
                                break;
                            list.Add((byte)data);
                        }
                        File.WriteAllBytes(savePath, list.ToArray());
                    }
                }
            }
            catch (WebException ex)
            {
                bol = false;
            }
            catch (Exception ex)
            {
                bol = false;
            }
            return bol;
        }

3。发送post数据

/// <summary>
/// 发送相关数据至页面
/// 进行登录操作
/// 并保存cookie
/// </summary>
/// <param name="postData"></param>
/// <param name="postUrl"></param>
/// <param name="cookie"></param>
/// <returns></returns>
public static ArrayList PostData(string postData, string postUrl, CookieContainer cookie)
{
    ArrayList list = new ArrayList();
    HttpWebRequest request;
    HttpWebResponse response;
    ASCIIEncoding encoding = new ASCIIEncoding();
    request = WebRequest.Create(postUrl) as HttpWebRequest;
    byte[] b = encoding.GetBytes(postData);
    request.UserAgent = "Mozilla/4.0";
    request.Method = "POST";
    request.CookieContainer = cookie;
    request.ContentLength = b.Length;
    using (Stream stream = request.GetRequestStream())
    {
        stream.Write(b, 0, b.Length);
    }

    try
    {
        //获取服务器返回的资源
        using (response = request.GetResponse() as HttpWebResponse)
        {
            using (StreamReader reader = new StreamReader(response.GetResponseStream(), Encoding.UTF8))
            {
                if (response.Cookies.Count > 0)
                    cookie.Add(response.Cookies);
                list.Add(cookie);
                list.Add(reader.ReadToEnd());
            }
        }
    }
    catch (WebException wex)
    {
        WebResponse wr = wex.Response;
        using (Stream st = wr.GetResponseStream())
        {
            using (StreamReader sr = new StreamReader(st, System.Text.Encoding.Default))
            {
                list.Add(sr.ReadToEnd());
            }
        }
    }
    catch (Exception ex)
    {
        list.Add("发生异常/n/r"+ex.Message);
    }
    return list;
}

4。就是第三步请求的链接地址换一个就行了

好了

以上核心代码已经贴出了

具体实现需要靠你们按照你们自己的逻辑

还有一些header能不写就不写，因为我2天前一直在获取返回response这地方报500错误。

找了N多代码，看了N多资料都不可以。最后将一些header注释掉就可以了，真郁闷。