// 比对固定时间，看是否超时。        private void CompareTime()        {            try            {                                dd = GetBeijingTime();                i = DateTime.Compare(dd, Convert.ToDateTime("2013-1-1 00:00:00"));                if (i < 0)                {                    dd = DateTime.Today;                }            }            catch            {                            }            i = DateTime.Compare(dd, Convert.ToDateTime("2014-5-5 00:00:00"));            if (i > 0)            {                btnOpen.Enabled = false;            }        }        // 获取北京时间        public static DateTime GetBeijingTime()        {            //t0 = new Date().getTime();            //nyear = 2011;            //nmonth = 7;            //nday = 5;            //nwday = 2;            //nhrs = 17;            //nmin = 12;            //nsec = 12;            DateTime dt;            WebRequest wrt = null;            WebResponse wrp = null;            try            {                wrt = WebRequest.Create("http://www.beijing-time.org/time.asp");                wrp = wrt.GetResponse();                string html = string.Empty;                using (Stream stream = wrp.GetResponseStream())                {                    using (StreamReader sr = new StreamReader(stream, Encoding.UTF8))                    {                        html = sr.ReadToEnd();                    }                }                string[] tempArray = html.Split(‘;‘);                for (int i = 0; i < tempArray.Length; i++)                {                    tempArray[i] = tempArray[i].Replace("\r\n", "");                }                string year = tempArray[1].Substring(tempArray[1].IndexOf("nyear=") + 6);                string month = tempArray[2].Substring(tempArray[2].IndexOf("nmonth=") + 7);                string day = tempArray[3].Substring(tempArray[3].IndexOf("nday=") + 5);                string hour = tempArray[5].Substring(tempArray[5].IndexOf("nhrs=") + 5);                string minite = tempArray[6].Substring(tempArray[6].IndexOf("nmin=") + 5);                string second = tempArray[7].Substring(tempArray[7].IndexOf("nsec=") + 5);                dt = DateTime.Parse(year + "-" + month + "-" + day + " " + hour + ":" + minite + ":" + second);            }            catch (WebException)            {                return DateTime.Parse("2011-4-1");            }            catch (Exception)            {                return DateTime.Parse("2011-1-1");            }            finally            {                if (wrp != null)                    wrp.Close();                if (wrt != null)                    wrt.Abort();            }            return dt;        }