之前看了很多获取网页源码的写法，要么有乱码，要么没考虑到gzip等压缩，比如有些网页这个HttpWebResponse 对象的CharacterSet是iso-8859-1,那么这种情况

我们根据它的charset读取。

还有个将流转成byte[] 数组的。。。发现GetResponseStream() 的流不能获取length属性

以下是源码

 public static HttpWebResponse GetResponse(string url, string method, string data = null, string reffer = null, CookieContainer cookieContainer = null)
        {
            //System.Net.ServicePointManager.Expect100Continue = true;
            HttpWebRequest req = (HttpWebRequest)WebRequest.Create(url);
            // 需要注意的： 
            //有的网页可能下不下来，有种种原因比如需要cookie,编码问题等等 
            //这是就要具体问题具体分析比如在头部加入cookie 
            // req.Headers.Add("Cookie", cookie); 
            //这样可能需要一些重载方法。根据需要写就可以了 

            //获取或设置用于对向 Internet 资源的请求进行身份验证的网络凭据。 
            req.Credentials = CredentialCache.DefaultCredentials;
            //如果服务器要验证用户名,密码 
            //NetworkCredential mycred = new NetworkCredential(struser, strpassword); 
            //myWebClient.Credentials = mycred; 
            //从资源下载数据并返回字节数组。（加@是因为网址中间有"/"符号） 
            //req.Proxy = null; //解决.net 4 第一次请求慢的问题
            req.Proxy = GetIEProxy(url);
            req.KeepAlive = true;
            req.Method = method.ToUpper();
            req.AllowAutoRedirect = true;
            req.ContentType = "application/x-www-form-urlencoded";
            req.Accept = "text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8";
            req.Headers.Add("Accept-Encoding", "gzip,deflate");
            //req.Connection = "keep-alive";
            req.Timeout = 10000;
            req.Referer = reffer;
            if (cookieContainer != null)
            {
                req.CookieContainer = cookieContainer;
            }
            else
            {

            }
            req.UserAgent = IE9;

            if (method.ToUpper() == "POST" && data != null)
            {
                byte[] postBytes = Encoding.UTF8.GetBytes(data); ;
                req.ContentLength = postBytes.Length;
                Stream st = req.GetRequestStream();
                st.Write(postBytes, 0, postBytes.Length);
                st.Close();
            }

            System.Net.ServicePointManager.ServerCertificateValidationCallback += (se, cert, chain, sslerror) =>{
                return true;
            };

            HttpWebResponse res = (HttpWebResponse)req.GetResponse();

            return res;
        }

        /**  
* 用getBytes(encoding)：返回字符串的一个byte数组  
* 当b[0]为 63时，应该是转码错误  
* A、不乱码的汉字字符串：  
* 1、encoding用GB2312时，每byte是负数；  
* 2、encoding用ISO8859_1时，b[i]全是63。  
* B、乱码的汉字字符串：  
* 1、encoding用ISO8859_1时，每byte也是负数；  
* 2、encoding用GB2312时，b[i]大部分是63。  
* C、英文字符串  
* 1、encoding用ISO8859_1和GB2312时，每byte都大于0；  
** 总结：给定一个字符串，用getBytes("iso8859_1")  
* 1、如果b[i]有63，不用转码； A-2  
* 2、如果b[i]全大于0，那么为英文字符串，不用转码； B-1  
* 3、如果b[i]有小于0的，那么已经乱码，要转码。 C-1  
*/
        public static String GetResponseString(string url, string method, string data = null, string reffer = null, CookieContainer cookieContainer = null)
        {
            HttpWebResponse res = GetResponse(url, method, data, reffer, cookieContainer);
            Stream receiveStream = res.GetResponseStream();
            if (res.ContentEncoding.ToLower().Contains("gzip"))
            {
                receiveStream = new GZipStream(receiveStream, CompressionMode.Decompress);
            }
            else
                if (res.ContentEncoding.ToLower().Contains("deflate"))
                {
                    receiveStream = new DeflateStream(receiveStream, CompressionMode.Decompress);
                }

            //获取网页字符编码描述信息 
            //Match charSetMatch = Regex.Match(strWebData, "<meta([^<]*)charset=([^<]*)\"", RegexOptions.IgnoreCase | RegexOptions.Multiline);
            //string webCharSet = charSetMatch.Groups[2].Value.Trim('\"');

            Encoding encode = Encoding.UTF8;
            if (res.CharacterSet != null && res.CharacterSet != "")
            {
                encode = Encoding.GetEncoding(res.CharacterSet);
            }

            StreamReader sr = new StreamReader(receiveStream, encode);
            string result = sr.ReadToEnd();
            sr.Close();

            if (res.CharacterSet != null && res.CharacterSet.ToLower() == "iso-8859-1")
            {
                Match charSetMatch = Regex.Match(result, "<meta.*?charset=(.*?)[\"|']", RegexOptions.IgnoreCase | RegexOptions.Multiline);
                if (charSetMatch.Success)
                {
                    string webCharSet = charSetMatch.Groups[1].Value.Replace("\"", "").Replace("'", "").Trim();
                    if (Encoding.GetEncoding(webCharSet) != encode)
                    {
                        // result = Encoding.GetEncoding(webCharSet).GetString(buffer);
                        sr = new StreamReader(receiveStream, Encoding.GetEncoding(webCharSet));
                        result = sr.ReadToEnd();
                        sr.Close();
                    }
                }
            }

            receiveStream.Close();
            res.Close();

            return result;
        }