帮看看 HttpWebRequest 相关的一段代码

        static public int GetHtml(HttpWebRequest request, ref string strContent)
        {
            try
            {
                strContent = "";

                HttpWebResponse response = (HttpWebResponse)request.GetResponse();

                Stream responseStream = response.GetResponseStream();

                if (response.ContentEncoding.ToLower().Contains("gzip"))
                {
                    responseStream = new GZipStream(responseStream, CompressionMode.Decompress, true);
                }
                else if (response.ContentEncoding.ToLower().Contains("deflate"))
                {
                    responseStream = new DeflateStream(responseStream, CompressionMode.Decompress);
                }

                string strCharacterSet = response.CharacterSet;

                if (strCharacterSet.Contains("ISO-8859-1"))
                {
                    strCharacterSet = "gbk";
                }


                StreamReader readStream = new StreamReader(responseStream, System.Text.Encoding.GetEncoding(strCharacterSet));
                strContent = readStream.ReadToEnd();

                responseStream.Close();

                response.Close();


                return 0;
            }
            catch(Exception ex)
            {
                CMyFun.WriteLog(ex.ToString());
                return -1;
            }

        }

偶尔出错， 什么原因？
—————————————————–
2011-08-11 18:28:15  System.ArgumentException: 基流不可读。
参数名: stream
   在 System.IO.Compression.DeflateStream..ctor(Stream stream, CompressionMode mode, Boolean leaveOpen, Boolean usingGZip)
   在 System.IO.Compression.GZipStream..ctor(Stream stream, CompressionMode mode, Boolean leaveOpen)
   在 Robot.CMyFun.GetHtml(HttpWebRequest request, String& strContent) 位置 D:\workspace\WOWRobot_20110218_multi\CMyFun.cs:行号 63