HttpUtil

using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using System.Net;
using System.Text;
using System.Threading.Tasks;
using System.Web;

namespace Common
{
   public class HttpUtil
    {
        private const string UserAgent = @"Mozilla/5.0 (Windows; Windows NT 6.1) AppleWebKit/534.23 (KHTML, like Gecko) Chrome/11.0.686.3 Safari/534.23";

        private readonly CookieContainer _cookie = new CookieContainer();

        public string Url { get; set; }

        public HttpUtil() { }

        public HttpUtil(string url)
        {
            Url = url;
        }

        /// <summary>
        /// GET请求
        /// </summary>
        /// <param name="data">需要请求的数据</param>
        public string Get(IDictionary<string, string> data)
        {
            ServicePointManager.DefaultConnectionLimit = 512;
            var str = data == null ? string.Empty : data.Keys.Aggregate(string.Empty, (current, key) => current + string.Format("{0}={1}&", key, System.Web.HttpUtility.UrlEncode(data[key]))).TrimEnd(new[] { ‘&‘ });
            if (string.IsNullOrEmpty(Url)) return string.Empty;
            var url = Url.TrimEnd(new[] { ‘?‘ });
            url += (url.IndexOf(‘?‘) > 0 ? "&" : "?") + str;
            var request = (HttpWebRequest)WebRequest.Create(url);
            //request.ServicePoint.SetTcpKeepAlive(true, 6000000, 100000);
            request.KeepAlive = true;
            request.CookieContainer = _cookie;
            request.UserAgent = UserAgent;
            request.Method = "GET";
            request.Timeout = 3000;
            try
            {
                //request.ServicePoint.ConnectionLeaseTimeout = 0;
                using (var response = (HttpWebResponse)request.GetResponse())
                {
                    var responseStream = response.GetResponseStream();
                    if (responseStream == null) return string.Empty;
                    try
                    {
                        using (var sr = new StreamReader(responseStream))
                        {
                            //response.Close();
                            return sr.ReadToEnd();
                        }
                    }
                    finally
                    {
                        response.Close();
                    }
                }
            }
            catch
            {
                return string.Empty;
            }
        }

        /// <summary>
        /// POST请求
        /// </summary>
        /// <param name="data">POST数据</param>
        /// <param name="refer">引用地址</param>
        /// <returns></returns>
        public string Post(IDictionary<string, string> data, string refer = "")
        {
            if (string.IsNullOrEmpty(Url)) return string.Empty;
            var str = data == null ? string.Empty : data.Keys.Aggregate(string.Empty, (current, key) => current + string.Format("{0}={1}&", key, data[key])).TrimEnd(new[] { ‘&‘ });

            var request = (HttpWebRequest)WebRequest.Create(Url);
            request.ServicePoint.ConnectionLimit = int.MaxValue;
            request.CookieContainer = _cookie;
            request.UserAgent = UserAgent;
            request.KeepAlive = true;
            request.Method = "POST";
            request.Referer = refer;
            request.Timeout = 3000;

            var postBytes = Encoding.ASCII.GetBytes(str);
            request.ContentType = "application/x-www-form-urlencoded; charset=UTF8";
            request.ContentLength = postBytes.Length;

            try
            {
                using (var requestStream = request.GetRequestStream())
                {
                    requestStream.Write(postBytes, 0, postBytes.Length);
                }
                using (var response = (HttpWebResponse)request.GetResponse())
                {
                    var responseStream = response.GetResponseStream();
                    if (responseStream == null) return string.Empty;
                    using (var sr = new StreamReader(responseStream))
                    {
                        return sr.ReadToEnd();
                    }
                }
            }
            catch
            {
                return string.Empty;
            }
        }

        /// <summary>
        /// POST请求
        /// </summary>
        /// <param name="data">POST数据</param>
        /// <param name="refer">引用地址</param>
        /// <returns></returns>
        public string Post(string data, string refer = "")
        {
            if (string.IsNullOrEmpty(Url)) return string.Empty;

            var request = (HttpWebRequest)WebRequest.Create(Url);
            request.ServicePoint.ConnectionLimit = int.MaxValue;
            request.CookieContainer = _cookie;
            request.UserAgent = UserAgent;
            request.KeepAlive = true;
            request.Method = "POST";
            request.Referer = refer;
            request.Timeout = 3000;

            var postBytes = Encoding.ASCII.GetBytes(data);
            request.ContentType = "text/html; charset=UTF8";
            request.ContentLength = postBytes.Length;

            try
            {
                using (var requestStream = request.GetRequestStream())
                {
                    requestStream.Write(postBytes, 0, postBytes.Length);
                }
                using (var response = (HttpWebResponse)request.GetResponse())
                {
                    var responseStream = response.GetResponseStream();
                    if (responseStream == null) return string.Empty;
                    using (var sr = new StreamReader(responseStream))
                    {
                        return sr.ReadToEnd();
                    }
                }
            }
            catch
            {
                return string.Empty;
            }
        }



/*
        private const string DefaultUserAgent = "Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.2; SV1; .NET CLR 1.1.4322; .NET CLR 2.0.50727)";
        private static readonly Encoding DefaultRequestEncoding = Encoding.GetEncoding("utf-8");

        /// <summary>
        /// 创建GET方式访问
        /// Author: George liu
        /// </summary>
        /// <param name="url">访问url</param>
        /// <param name="timeout">超时时间</param>
        /// <param name="userAgent">用户代理</param>
        /// <param name="cookies">cookie信息</param>
        /// <returns></returns>
        public static HttpWebResponse CreateGetHttpResponse(string url, int? timeout = null, string userAgent = null, CookieCollection cookies = null)
        {
            if (string.IsNullOrEmpty(url)) { return null; }
            HttpWebRequest request = WebRequest.Create(url) as HttpWebRequest;
            request.Method = "GET";
            request.UserAgent = DefaultUserAgent;
            if (!string.IsNullOrEmpty(userAgent)) { request.UserAgent = userAgent; }
            if (timeout.HasValue) { request.Timeout = timeout.Value; }
            if (cookies != null)
            {
                request.CookieContainer = new CookieContainer();
                request.CookieContainer.Add(cookies);
            }
            return request.GetResponse() as HttpWebResponse;
        }

        /// <summary>
        /// 创建POST访问方式
        /// Author: George liu
        /// </summary>
        /// <param name="url">访问url</param>
        /// <param name="parameters">参数键值对</param>
        /// <param name="timeout">超时时间</param>
        /// <param name="userAgent">用户代理</param>
        /// <param name="requestEncoding">编码类型</param>
        /// <param name="cookies">cookie信息</param>
        /// <returns></returns>
        public static HttpWebResponse CreatePostHttpResponse(string url, IDictionary<string, string> parameters = null, int? timeout = null, string userAgent = null,
                                                             Encoding requestEncoding = null, CookieCollection cookies = null)
        {
            if (string.IsNullOrEmpty(url)) { return null; }
            HttpWebRequest request = WebRequest.Create(url) as HttpWebRequest;
            request.Method = "POST";
            request.ContentType = "application/x-www-form-urlencoded";
            request.UserAgent = DefaultUserAgent;
            if (!string.IsNullOrEmpty(userAgent)) { request.UserAgent = userAgent; }
            if (timeout.HasValue) { request.Timeout = timeout.Value; }
            if (requestEncoding == null) { requestEncoding = DefaultRequestEncoding; }
            if (cookies != null)
            {
                request.CookieContainer = new CookieContainer();
                request.CookieContainer.Add(cookies);
            }
            if (parameters != null && parameters.Count > 0)
            {
                StringBuilder buffer = new StringBuilder();
                var keyArray = parameters.Keys.ToArray();
                for (int i = 0; i < keyArray.Length; i++)
                {
                    if (i > 0)
                    {
                        buffer.AppendFormat("&{0}={1}", keyArray[i], parameters[keyArray[i]]);
                    }
                    else
                    {
                        buffer.AppendFormat("{0}={1}", keyArray[i], parameters[keyArray[i]]);
                    }
                }
                byte[] data = requestEncoding.GetBytes(buffer.ToString());
                using (Stream stream = request.GetRequestStream())
                {
                    stream.Write(data, 0, data.Length);
                }
            }
            return request.GetResponse() as HttpWebResponse;
        }

        /// <summary>
        /// 获取客户端IP
        /// </summary>
        /// <returns></returns>
        public static string GetClientIP()
        {
            var clientIp = string.Empty;
            var request = HttpContext.Current.Request;
            if (request.ServerVariables["HTTP_VIA"] != null)
            {
                clientIp = request.ServerVariables["HTTP_X_FORWARDED_FOR"].ToString();
            }
            else
            {
                clientIp = request.ServerVariables["REMOTE_ADDR"].ToString();
            }
            return clientIp;
        }*/
    }
}