Code
using System;
using System.Collections.Generic;
using System.Text;
using System.Net;
using System.IO;

namespace SNSHelper.Common
{
    class HttpHelper
    {
        #region 私有变量
        private CookieContainer cc;
        private string contentType = "application/x-www-form-urlencoded";
        private string accept = "image/gif, image/x-xbitmap, image/jpeg, image/pjpeg, application/x-shockwave-flash, application/x-silverlight, application/vnd.ms-excel, application/vnd.ms-powerpoint, application/msword, application/x-ms-application, application/x-ms-xbap, application/vnd.ms-xpsdocument, application/xaml+xml, application/x-silverlight-2-b1, */*";
        private string userAgent = "Mozilla/4.0 (compatible; MSIE 7.0; Windows NT 5.1; .NET CLR 2.0.50727; .NET CLR 3.0.04506.648; .NET CLR 3.5.21022)";
        private Encoding encoding = Encoding.GetEncoding("utf-8");
        #endregion

#region 属性
        /// <summary>
        /// Cookie容器
        /// </summary>
        public CookieContainer CookieContainer
        {
            get
            {
                return cc;
            }
        }

/// <summary>
        /// 获取网页源码时使用的编码
        /// </summary>
        /// <value></value>
        public Encoding Encoding
        {
            get
            {
                return encoding;
            }
            set
            {
                encoding = value;
            }
        }
        #endregion

#region 构造函数
        /// <summary>
        /// Initializes a new instance of the <see cref="HttpHelper"/> class.
        /// </summary>
        public HttpHelper()
        {
            cc = new CookieContainer();
        }

/// <summary>
        /// Initializes a new instance of the <see cref="HttpHelper"/> class.
        /// </summary>
        /// <param name="cc">The cc.</param>
        public HttpHelper(CookieContainer cc)
        {
            this.cc = cc;
        }

/// <summary>
        /// Initializes a new instance of the <see cref="HttpHelper"/> class.
        /// </summary>
        /// <param name="contentType">Type of the content.</param>
        /// <param name="accept">The accept.</param>
        /// <param name="userAgent">The user agent.</param>
        public HttpHelper(string contentType, string accept, string userAgent)
        {
            this.contentType = contentType;
            this.accept = accept;
            this.userAgent = userAgent;
        }

/// <summary>
        /// Initializes a new instance of the <see cref="HttpHelper"/> class.
        /// </summary>
        /// <param name="cc">The cc.</param>
        /// <param name="contentType">Type of the content.</param>
        /// <param name="accept">The accept.</param>
        /// <param name="userAgent">The user agent.</param>
        public HttpHelper(CookieContainer cc, string contentType, string accept, string userAgent)
        {
            this.cc = cc;
            this.contentType = contentType;
            this.accept = accept;
            this.userAgent = userAgent;
        }
        #endregion

#region 公共方法
        /// <summary>
        /// 获取指定页面的HTML代码
        /// </summary>
        /// <param name="url">指定页面的路径</param>
        /// <param name="postData">回发的数据</param>
        /// <param name="isPost">是否以post方式发送请求</param>
        /// <param name="cookieCollection">Cookie集合</param>
        /// <returns></returns>
        public string GetHtml(string url, string postData, bool isPost, CookieContainer cookieContainer)
        {
            if (string.IsNullOrEmpty(postData))
            {
                return GetHtml(url, cookieContainer);
            }

byte[] byteRequest = Encoding.Default.GetBytes(postData);

HttpWebRequest httpWebRequest;
            httpWebRequest = (HttpWebRequest)HttpWebRequest.Create(url);

httpWebRequest.CookieContainer = cookieContainer;
            httpWebRequest.ContentType = contentType;
            httpWebRequest.Referer = url;
            httpWebRequest.Accept = accept;
            httpWebRequest.UserAgent = userAgent;
            httpWebRequest.Method = isPost ? "POST" : "GET";
            httpWebRequest.ContentLength = byteRequest.Length;

Stream stream = httpWebRequest.GetRequestStream();
            stream.Write(byteRequest, 0, byteRequest.Length);
            stream.Close();

HttpWebResponse httpWebResponse;
            httpWebResponse = (HttpWebResponse)httpWebRequest.GetResponse();
            Stream responseStream = httpWebResponse.GetResponseStream();
            StreamReader streamReader = new StreamReader(responseStream, encoding);
            string html = streamReader.ReadToEnd();
            streamReader.Close();
            responseStream.Close();

return html;
        }

/// <summary>
        /// 获取指定页面的HTML代码
        /// </summary>
        /// <param name="url">指定页面的路径</param>
        /// <param name="cookieCollection">Cookie集合</param>
        /// <returns></returns>
        public string GetHtml(string url, CookieContainer cookieContainer)
        {
            HttpWebRequest httpWebRequest;

httpWebRequest = (HttpWebRequest)HttpWebRequest.Create(url);
            httpWebRequest.CookieContainer = cookieContainer;
            httpWebRequest.ContentType = contentType;
            httpWebRequest.Referer = url;
            httpWebRequest.Accept = accept;
            httpWebRequest.UserAgent = userAgent;
            httpWebRequest.Method = "GET";

HttpWebResponse httpWebResponse;
            httpWebResponse = (HttpWebResponse)httpWebRequest.GetResponse();
            Stream responseStream = httpWebResponse.GetResponseStream();
            StreamReader streamReader = new StreamReader(responseStream, encoding);
            string html = streamReader.ReadToEnd();
            streamReader.Close();
            responseStream.Close();

return html;
        }

/// <summary>
        /// 获取指定页面的HTML代码
        /// </summary>
        /// <param name="url">指定页面的路径</param>
        /// <returns></returns>
        public string GetHtml(string url)
        {
            return GetHtml(url, cc);
        }

/// <summary>
        /// 获取指定页面的HTML代码
        /// </summary>
        /// <param name="url">指定页面的路径</param>
        /// <param name="postData">回发的数据</param>
        /// <param name="isPost">是否以post方式发送请求</param>
        /// <returns></returns>
        public string GetHtml(string url, string postData, bool isPost)
        {
            return GetHtml(url, postData, isPost, cc);
        }
        #endregion
    }
}

Code
/// <summary>
/// 登录开心网
/// </summary>
/// <param name="loginEmail">Email</param>
/// <param name="loginPassword">密码</param>
/// <returns></returns>
public static bool Login(string loginEmail, string loginPassword)
{
    string loginUrl = "http://www.kaixin001.com/login/login.php";
    string postData = string.Format("url=/home/&invisible_mode=0&email={0}&password={1}", loginEmail, loginPassword);
    string result = httpHelper.GetHtml(loginUrl, postData, true, cookieContainer);

return isLogin = result.Contains("我的首页");
}

Code
CookieContainer cookie = Utility.Cookies;
string parkingHTML = new HttpHelper().GetHtml(AppUrl + AppID, cookie);  // AppUrl = "http://www.kaixin001.com/app/app.php?aid="; AppID = "1040";
if (!parkingHTML.Contains("争车位"))
{
    throw new Exception("读取争车位信息出错");
}