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; //存储验证码cookie

    #region 登录
    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;//获取验证码时候获取到的cookie会附加在这个容器里面
        request.KeepAlive = true;//建立持久性连接
        //整数据
        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;

        //发送数据 using结束代码段释放
        using (Stream requestStm = request.GetRequestStream())
        {
          requestStm.Write(bytepostData, 0, bytepostData.Length);
        }

        //响应
        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 获取验证码
    public Stream getCodeStream(string codeUrl)
    {

      //验证码请求
      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();//更新验证码
    }

    //更新验证码
    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();//更新验证码
    }

    private void picValidate_Click(object sender, EventArgs e)
    {
      ReflshPicImage();//更新验证码
    }
  }
}