网页内容若使用gzip压缩--获得页面源码

 if (String.IsNullOrEmpty(strUrl))      

 { return "抓取地址为空!"; } 
            HttpWebRequest req = null; 
            HttpWebResponse resp = null;
            Stream stream = null;
            StreamReader read = null; 
            try 
            {
                req = (HttpWebRequest)HttpWebRequest.Create(strUrl); 
                req.UserAgent = "Mozilla/5.0 (Windows NT 5.1; rv:14.0) Gecko/20100101 Firefox/14.0.1";
                req.Accept = "text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8"; 
                req.Headers.Add("Accept-Language", "zh-cn,zh;q=0.8,en-us;q=0.5,en;q=0.3"); 
                req.ContentType = "text/html"; req.Timeout = 20000; // 设置访问来源地址，避免被检测到非本地址访问 
                if (String.IsNullOrEmpty(referer)) 
                { req.Referer = req.RequestUri.Host; } 
                else { req.Referer = referer; } 
                // 设置 cookie 验证信息 
                CookieContainer cc = new CookieContainer();
                req.CookieContainer = cc;
                foreach (Cookie cook in cookies) 
                { 
                    Cookie c = new Cookie(cook.Name, cook.Value); 
                    if (cookieDomain != null) 
                        c.Domain = cookieDomain; cc.Add(c); 
                } 
                resp = (HttpWebResponse)req.GetResponse();
                Encoding enc; 
                // 解决 .NET 编码识别错误的问题 
                if ("ISO-8859-1" == resp.CharacterSet)
                { 
                    // 使用指定的编码格式校正
                    enc = encoding; 
                } else
                { 
                    // 自动使用识别出来的编码格式 
                    enc = Encoding.GetEncoding(resp.CharacterSet);
                } 
                //if (isAjax) //{ // return GetAjaxUseWebBrowser(strUrl); //} 
                string sHTML = string.Empty; 
                // 从网站Url获取内容流 
                stream = resp.GetResponseStream(); 
                // 判断内容是否使用gzip压缩 
                if (resp.ContentEncoding.ToLower().Contains("gzip")) 
                { 
                    // 设置gzip解压缩
                    stream = new GZipStream(stream, CompressionMode.Decompress);
                    read = new StreamReader(stream, enc); 
                    sHTML = read.ReadToEnd(); 
                } 
                else 
                { 
                    string sChartSet = "";
                    read = new StreamReader(stream, enc);
                    sHTML = read.ReadToEnd(); 
                    // 获取内容使用的编码格式 
                    Match charSetMatch = Regex.Match(sHTML, "charset=(?<code>[a-zA-Z0-9\\-]+)", RegexOptions.IgnoreCase); 
                    sChartSet = charSetMatch.Groups["code"].Value;
                    //if it's not utf-8,we should redecode the html. 
                    Regex rx = new Regex("([\u4e00-\u9fa5]{2,4})"); 
                    // 如果内容为UTF-8编码格式则进行再次转码
                    if (!rx.IsMatch(sHTML)) 
                    { 
                        if (!string.IsNullOrEmpty(sChartSet.Trim()))
                            sHTML = Encoding.GetEncoding(sChartSet).GetString(enc.GetBytes(sHTML));
                    } 
                } 
                // 去除换行符 
                sHTML = sHTML.Replace("\n", "").Replace("\r", "").Replace("\t", ""); 
                // 设置抓取任务状态为 1:=成功 
                crawlerState = IWOMWebCrawlerDbLayer.Common.CrawlerState.Success; return sHTML;
            } 
            catch (Exception ex) 
            {  } 
            return "";