一个上好的C# http/https类

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Net.Security;
using System.Security.Cryptography.X509Certificates;
using System.ServiceModel.Security;
using System.Net;
using System.IO;
using System.IO.Compression;
using System.Text.RegularExpressions;

namespace Lzp.Service
{

    /// <summary>  
    /// 有关HTTP/HTTPS请求的辅助类 lzpong
    /// 默认 UTF-8 编码
    /// </summary>  
    public class HTTPS
    {
        public HTTPS()
        {
            spt = SecurityProtocolType.Tls;
            requestEncoding = Encoding.GetEncoding("UTF-8");
            requestUserAgent = DefaultUserAgent;
        }
        /// <summary>
        /// SecurityProtocolType
        /// 如果https出现"基础连接..."或"ssl/tls..."错误,更改此属性; 也可能需要升级 .net 已支持更新的安全协议
        /// </summary>
        public static SecurityProtocolType spt { get; set; }
        //设置编码   默认编码是UTF-8
        public static Encoding requestEncoding { get; set; }
        //设置编码
        public static void SetEncoding(string endcode) { requestEncoding = Encoding.GetEncoding(endcode); }

        private static string requestUserAgent = DefaultUserAgent;
        private static readonly string DefaultUserAgent = "Mozilla/5.0 (Windows NT 6.1; WOW64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/45.0.2454.101 Safari/537.36";
        //设置浏览器版本
        public static void SetUserAgent(string userAgent = null) { if (!String.IsNullOrWhiteSpace(userAgent))requestUserAgent = userAgent; else requestUserAgent = DefaultUserAgent; }
        /// <summary>
        /// 创建GET方式的HTTP/HTTPS请求
        /// </summary>
        /// <param name="url">请求的URL</param>
        /// <param name="timeout">请求的超时时间</param>
        /// <param name="userAgent">请求的客户端浏览器信息，可以为空</param>
        /// <param name="requestEncoding">发送HTTP请求时所用的编码</param>
        /// <param name="cookies">随同HTTP请求发送的Cookie信息，如果不需要身份验证可以为空</param>
        /// <returns></returns>
        public static HttpWebResponse CreateGet(string url, int? timeout = null, string userAgent = null, CookieCollection cookies = null)
        {
            return Create(url, null, "GET", requestEncoding, timeout, cookies);
        }
        /// <summary>
        /// 创建POST方式的HTTP/HTTPS请求
        /// </summary>
        /// <param name="url">请求的URL</param>
        /// <param name="parameters">随同请求POST的数据</param>
        /// <param name="timeout">请求的超时时间</param>
        /// <param name="userAgent">请求的客户端浏览器信息，可以为空</param>
        /// <param name="requestEncoding">发送HTTP请求时所用的编码</param>
        /// <param name="cookies">随同HTTP请求发送的Cookie信息，如果不需要身份验证可以为空</param>
        /// <returns></returns>
        public static HttpWebResponse CreatePost(string url, string parameters = null, int? timeout = null, CookieCollection cookies = null)
        {
            return Create(url, parameters, "POST", requestEncoding, timeout, cookies);
        }
        /// <summary>
        /// 创建HTTP/HTTPS请求
        /// </summary>
        /// <param name="url">请求的URL</param>
        /// <param name="parameters">随同请求POST的参数名称及参数值字典</param>
        /// <param name="timeout">请求的超时时间</param>
        /// <param name="userAgent">请求的客户端浏览器信息，可以为空</param>
        /// <param name="requestEncoding">发送HTTP请求时所用的编码</param>
        /// <param name="cookies">随同HTTP请求发送的Cookie信息，如果不需要身份验证可以为空</param>
        /// <returns></returns>
        public static HttpWebResponse Create(string url, string parameters=null, string method = "GET", Encoding requestEncoding = null, int? timeout = null, CookieCollection cookies = null)
        {
            if (string.IsNullOrEmpty(url))
                throw new ArgumentNullException("url");

            if (requestEncoding == null)
                requestEncoding=Encoding.GetEncoding("UTF-8");

            HttpWebRequest request = null;
            //如果是发送HTTPS请求  
            if (url.StartsWith("https", StringComparison.OrdinalIgnoreCase))
            {
                ServicePointManager.SecurityProtocol = spt;
                ServicePointManager.ServerCertificateValidationCallback = new RemoteCertificateValidationCallback(CheckValidationResult);
                request = WebRequest.Create(url) as HttpWebRequest;
                request.ProtocolVersion = HttpVersion.Version10;
            }
            else
                request = WebRequest.Create(url) as HttpWebRequest;

            request.Method = method;
            request.UserAgent = requestUserAgent;

            if (timeout.HasValue)
                request.Timeout = timeout.Value;

            if (cookies != null)
            {
                request.CookieContainer = new CookieContainer();
                request.CookieContainer.Add(cookies);
            }
            //如果需要POST数据  
            if (method == "POST")
            {
                request.ContentType = "application/x-www-form-urlencoded";
                if (!String.IsNullOrWhiteSpace(parameters))
                {
                    byte[] data = requestEncoding.GetBytes(parameters);
                    using (Stream stream = request.GetRequestStream())
                    {
                        stream.Write(data, 0, data.Length);
                    }
                }
            }
            return request.GetResponse() as HttpWebResponse;
        }
        private static bool CheckValidationResult(object sender, X509Certificate certificate, X509Chain chain, SslPolicyErrors errors)
        {
            return true; //总是接受
        }
    }
}