HttpWebRequest和HttpWebResponse類是用於發送和接收HTTP數據的最好選擇。它們支持一系列有用的屬性。

模擬藝龍旅遊網登錄

想模擬登錄，首先整理一下流程

1.通過360瀏覽器(IE,火狐等等)F12開發人員工具抓到相關數據

2.獲取驗證碼（拿到cookie），登錄時也需要使用

3.登錄

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F12調出開發人員工具，輸入用戶名，密碼登錄，看我們抓到了什麽信息。 （此處為360瀏覽器）

Form Data:這個是我們要POST傳輸的數據：

userName=xzdylyh&passwd=12313&validateCode=驗證碼&rememberMe=false （註意此處可能每個人略有不同）

其它一些重要信息在Request Headers中

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我使用C# 設計的winform界面

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
 
using System.Threading.Tasks;
using System.Web;
using System.Net;
using System.IO;
using System.Data;
namespace HTTPHELPER
{
    public  class ELOGN_LOGIN
    {

       public static CookieContainer container = null; //存儲驗證碼cookie

        #region 登錄
        public string  requestM(string
 
 uName,string passwd,string vaildate)
        {
            HttpWebRequest request = null;
            HttpWebResponse response = null;
            try
            {
                request = (HttpWebRequest)HttpWebRequest.Create("https://secure.elong.com/passport/ajax/elongLogin");
                request.Method = "Post";
                request.ContentType = "application/x-www-form-urlencoded; charset=UTF-8";
                request.UserAgent = "Mozilla/5.0 (Windows NT 10.0; WOW64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/45.0.2454.101 Safari/537.36";
                request.AllowAutoRedirect = true;
                request.CookieContainer = container;//獲取驗證碼時候獲取到的cookie會附加在這個容器裏面
                request.KeepAlive = true;//建立持久性連接
                //整數據
                string postData = string.Format("userName={0}&passwd={1}&validateCode={2}&rememberMe=true", uName, passwd, vaildate);
                ASCIIEncoding encoding = new ASCIIEncoding();
                byte[] bytepostData = encoding.GetBytes(postData);
                request.ContentLength = bytepostData.Length;

                //發送數據  using結束代碼段釋放
                using (Stream requestStm = request.GetRequestStream())
                {
                    requestStm.Write(bytepostData, 0, bytepostData.Length);
                }

                //響應
                response = (HttpWebResponse)request.GetResponse();
                string text = string.Empty;
                using (Stream responseStm = response.GetResponseStream())
                {
                    StreamReader redStm = new StreamReader(responseStm, Encoding.UTF8);
                    text = redStm.ReadToEnd();
                }

               return text;
            }
            catch (Exception ex)
            {
                var msg = ex.Message;
                return msg;
            }

        }
        #endregion 

        #region 獲取驗證碼
        public Stream getCodeStream(string codeUrl)
        {

            //驗證碼請求
           HttpWebRequest request = (HttpWebRequest)WebRequest.Create(codeUrl);
            request.Method = "GET";
            request.ContentType = "application/x-www-form-urlencoded";
            request.UserAgent = "Mozilla/5.0 (Windows NT 6.1; WOW64; rv:5.0.1) Gecko/20100101 Firefox/5.0.1";
            request.Accept = "image/webp,*/*;q=0.8";
            request.CookieContainer = new CookieContainer();//!Very Important.!!!
            container = request.CookieContainer;
            var c = request.CookieContainer.GetCookies(request.RequestUri);
            HttpWebResponse  response = (HttpWebResponse)request.GetResponse();
            response.Cookies = container.GetCookies(request.RequestUri);
          
          Stream stream = response.GetResponseStream();
          return stream;
        }
    }
        #endregion
}

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Forms;
using System.IO;
using HTTPHELPER;
namespace WindowsFormsApplication8
{
    public partial class ELONG_LOGIN_FORM : Form
    {
        public ELONG_LOGIN_FORM()
        {
            InitializeComponent();
        }

        private void button1_Click(object sender, EventArgs e)
        {
            
            ELOGN_LOGIN elongLogin = new ELOGN_LOGIN();
            
            var rmsg = elongLogin.requestM(txtuserName.Text,txtPassword.Text,txtVaildata.Text);
            MessageBox.Show(rmsg);
        }

        private void ELONG_LOGIN_FORM_Load(object sender, EventArgs e)
        {
            ReflshPicImage();//更新驗證碼
        }

        //更新驗證碼
        public void ReflshPicImage()
        {
            string codeUrl = "https://secure.elong.com/passport/getValidateCode";
            ELOGN_LOGIN agent = new ELOGN_LOGIN();
            Stream stmImage = agent.getCodeStream(codeUrl);
            picValidate.Image = Image.FromStream(stmImage);
        }

        private void btnReValidate_Click(object sender, EventArgs e)
        {
            ReflshPicImage();//更新驗證碼
        }

        private void picValidate_Click(object sender, EventArgs e)
        {
            ReflshPicImage();//更新驗證碼
        }
    }
}

最後執行效果，登錄的session已經成功返回。

原文鏈接：https://www.cnblogs.com/yhleng/p/6728864.html

ASP.NET HttpWebRequest和HttpWebResponse