C# 下载搜狗词库

HttpWebRequest request = (HttpWebRequest)WebRequest.Create(url);
                    string[] userAgent = new string[]{"Mozilla/5.0 (Windows NT 6.1; WOW64; rv:15.0) Gecko/20120427 Firefox/15.0a1", //ff
                                                        "Mozilla/5.0 (MSIE 9.0; Windows NT 6.1; Trident/5.0)", //ie 9
                                                        "Mozilla/5.0 (Windows; U; Windows NT 5.2) AppleWebKit/525.13 (KHTML, like Gecko) Chrome/0.2.149.27 Safari/525.13"//chrome
                                                      };
                    //request.UserAgent = "Mozilla/5.0 (Windows; U; Windows NT 5.2) AppleWebKit/525.13 (KHTML, like Gecko) Chrome/0.2.149.27 Safari/525.13";
                    Random ra = new Random();
                    int userAgentIndex = ra.Next(0, 3);
                    request.UserAgent = userAgent[userAgentIndex];

                    request.Credentials = CredentialCache.DefaultCredentials;
                    request.Method = "GET";
                    request.Referer = refer;

                    request.KeepAlive = false;
                    request.Timeout = 5000;
                    //request.ContentType="text/plain";
                    request.ProtocolVersion = HttpVersion.Version10;

                    HttpWebResponse response;
                    Stream resStream;
                    response = (HttpWebResponse)request.GetResponse();
                    resStream = response.GetResponseStream();

                    int count = (int)response.ContentLength;
                    int offset = 0;
                    byte[] buf = new byte[count];
                    while (count > 0)
                    {
                        int n = resStream.Read(buf, offset, count);
                        if (n == 0)
                            break;
                        count -= n;
                        offset += n;
                    }