/// 
        /// 获取指定URL的HTML源代码        /// 
        ///         /// 如果为NULL 则自动识别        /// 
             public static string GetWebHtml(string url, Encoding encoding)        {            try            {                HttpWebRequest hwr = (HttpWebRequest)HttpWebRequest.Create(url);                HttpWebResponse res;                try                {                    res = (HttpWebResponse)hwr.GetResponse();                }                catch                {                    return string.Empty;                }                if (res.StatusCode == HttpStatusCode.OK)                {                    using (Stream mystream = res.GetResponseStream())                    {                        //没有指定编码，                        if (encoding == null)                        {                            return DecodeData(mystream, res);                        }                        //指定了编码                        else                        {                            using (StreamReader reader = new StreamReader(mystream, encoding))                            {                                return reader.ReadToEnd();                            }                        }                    }                }                return null;            }            catch            {                return null;            }        }        private static string DecodeData(Stream responseStream, HttpWebResponse response)        {            string name = null;            string text2 = response.Headers["content-type"];            if (text2 != null)            {                int index = text2.IndexOf("charset=");                if (index != -1)                {                    name = text2.Substring(index + 8);                }            }            MemoryStream stream = new MemoryStream();            byte[] buffer = new byte[0x400];            for (int i = responseStream.Read(buffer, 0, buffer.Length); i > 0; i = responseStream.Read(buffer, 0, buffer.Length))            {                stream.Write(buffer, 0, i);            }            responseStream.Close();            if (name == null)            {                MemoryStream stream3 = stream;                stream3.Seek((long)0, SeekOrigin.Begin);                string text3 = new StreamReader(stream3, Encoding.ASCII).ReadToEnd();                if (text3 != null)                {                    int startIndex = text3.IndexOf("charset=");                    int num4 = -1;                    if (startIndex != -1)                    {                        num4 = text3.IndexOf("\"", startIndex);                        if (num4 != -1)                        {                            int num5 = startIndex + 8;                            name = text3.Substring(num5, (num4 - num5) + 1).TrimEnd(new char[] { '>', '"' });                        }                    }                }            }            Encoding aSCII = null;            if (name == null)            {                aSCII = Encoding.GetEncoding("gb2312");            }            else            {                try                {                    if (name == "GBK")                    {                        name = "GB2312";                    }                    aSCII = Encoding.GetEncoding(name);                }                catch                {                    aSCII = Encoding.GetEncoding("gb2312");                }            }            stream.Seek((long)0, SeekOrigin.Begin);            StreamReader reader2 = new StreamReader(stream, aSCII);            return reader2.ReadToEnd();        }