.net 环境下get 获取页面出现乱码问题解决

/// <summary>
        /// 获取页面内容
        /// </summary>
        /// <param name="Url">链接地址</param>
        /// <returns></returns>
        public static string GetWebContent(string Url)
        {

            string strResult = "", strCharacterSet="";
            try
            {
                HttpWebRequest request = (HttpWebRequest)WebRequest.Create(Url);
                StreamReader streamReader;
                //声明一个HttpWebRequest请求
                request.Timeout = 30000;
                //设置连接超时时间
                request.Headers.Set("Pragma", "no-cache");
                HttpWebResponse response = (HttpWebResponse)request.GetResponse();
                Stream streamReceive = response.GetResponseStream();
                Encoding encoding;
                string strPageCharacterSet = response.CharacterSet.ToLower();//获取页面响应中定义的编码字符串
                encoding = Encoding.GetEncoding(strPageCharacterSet);
                streamReader = new StreamReader(streamReceive, encoding);
                strResult = streamReader.ReadToEnd();
                strResult = StringHelps.RepalceStr(strResult, 0);
                strCharacterSet = GetEncoding(strResult).ToLower();//获取页面html中声明的编码字符串
                if (!strCharacterSet.Equals(strPageCharacterSet))//比较两者的编码格式是否一致，如果不一致，以页面中定义的编码格式再次去获取页面内容
                {
                    strResult = GetWebContentByCharecterSet(Url, strCharacterSet);
                }
                if (string.IsNullOrEmpty(strResult))
                {
                    streamReader = new StreamReader(streamReceive, encoding);
                    strResult = streamReader.ReadToEnd();
                }
            }
            catch (Exception ex)
            {
                LogHelper.Save("获取页面出现乱码" + Url + ex.ToString());
            }
            return strResult;
        }
        /// <summary>
        /// 指定编码格式获取页面代码
        /// </summary>
        /// <param name="Url"></param>
        /// <param name="strCharacterSet"></param>
        /// <returns></returns>
        public static string GetWebContentByCharecterSet(string Url,string strCharacterSet)
        {

            string strResult = "";
            try
            {
                HttpWebRequest request = (HttpWebRequest)WebRequest.Create(Url);
                StreamReader streamReader;
                //声明一个HttpWebRequest请求
                request.Timeout = 30000;
                //设置连接超时时间
                request.Headers.Set("Pragma", "no-cache");
                HttpWebResponse response = (HttpWebResponse)request.GetResponse();
                Stream streamReceive = response.GetResponseStream();
                Encoding encoding;
                encoding = Encoding.GetEncoding(strCharacterSet);
                streamReader = new StreamReader(streamReceive, encoding);
                strResult = streamReader.ReadToEnd();
            }
            catch (Exception ex)
            {
                LogHelper.Save("获取页面出现异常" + Url + ex.ToString());
            }
            return strResult;
        }
        /// <summary>
        /// 根据网页的HTML内容提取网页的Encoding
        /// </summary>
        /// <param name="html"></param>
        /// <returns></returns>
        static string GetEncoding(string html)
        {
            string pattern = @"(?i)charset=(?<charset>[-a-zA-Z_0-9]+)";
            string charset = Regex.Match(html, pattern).Groups["charset"].Value;
            if (string.IsNullOrEmpty(charset))
                charset = "utf-8";
            return charset;
        }