C#获取获取北京时间多种方法

#region 获取网络时间
///<summary>
/// 获取中国国家授时中心网络服务器时间发布的当前时间
///</summary>
///<returns></returns>
publicstatic DateTime GetChineseDateTime()
{
    DateTime res = DateTime.MinValue;
    try
    {
        string url = "http://www.time.ac.cn/stime.asp";
        HttpHelper helper = new HttpHelper();
        helper.Encoding = Encoding.Default;
        string html = helper.GetHtml(url);
        string patDt = @"\d{4}年\d{1,2}月\d{1,2}日";
        string patHr = @"hrs\s+=\s+\d{1,2}";
        string patMn = @"min\s+=\s+\d{1,2}";
        string patSc = @"sec\s+=\s+\d{1,2}";
        Regex regDt = new Regex(patDt);
        Regex regHr = new Regex(patHr);
        Regex regMn = new Regex(patMn);
        Regex regSc = new Regex(patSc);

        res = DateTime.Parse(regDt.Match(html).Value);
        int hr = GetInt(regHr.Match(html).Value, false);
        int mn = GetInt(regMn.Match(html).Value, false);
        int sc = GetInt(regSc.Match(html).Value, false);
        res = res.AddHours(hr).AddMinutes(mn).AddSeconds(sc);
    }
    catch { }
    return res;
}

///<summary>
/// 从指定的字符串中获取整数
///</summary>
///<param name="origin">原始的字符串</param>
///<param name="fullMatch">是否完全匹配，若为false，则返回字符串中的第一个整数数字</param>
///<returns>整数数字</returns>
privatestaticint GetInt(string origin, bool fullMatch)
{
    if (string.IsNullOrEmpty(origin))
    {
        return0;
    }
    origin = origin.Trim();
    if (!fullMatch)
    {
        string pat = @"-?\d+";
        Regex reg = new Regex(pat);
        origin = reg.Match(origin.Trim()).Value;
    }
    int res = 0;
    int.TryParse(origin, out res);
    return res;
}
#endregion

///<summary>
/// 获取标准北京时间1
///</summary>
///<returns></returns>
publicstatic DateTime GetStandardTime()
{
    //<?xml version="1.0" encoding="GB2312" ?>
    //- <ntsc>
    //- <time>
    //  <year>2011</year>
    //  <month>7</month>
    //  <day>10</day>
    //  <Weekday />
    //  <hour>19</hour>
    //  <minite>45</minite>
    //  <second>37</second>
    //  <Millisecond />
    //  </time>
    //  </ntsc>
    DateTime dt;
    WebRequest wrt = null;
    WebResponse wrp = null;
    try
    {
        wrt = WebRequest.Create("http://www.time.ac.cn/timeflash.asp?user=flash");
        wrt.Credentials = CredentialCache.DefaultCredentials;

        wrp = wrt.GetResponse();
        StreamReader sr = new StreamReader(wrp.GetResponseStream(), Encoding.UTF8);
        string html = sr.ReadToEnd();

        sr.Close();
        wrp.Close();

        int yearIndex = html.IndexOf("<year>") + 6;
        int monthIndex = html.IndexOf("<month>") + 7;
        int dayIndex = html.IndexOf("<day>") + 5;
        int hourIndex = html.IndexOf("<hour>") + 6;
        int miniteIndex = html.IndexOf("<minite>") + 8;
        int secondIndex = html.IndexOf("<second>") + 8;

        string year = html.Substring(yearIndex, html.IndexOf("</year>") - yearIndex);
        string month = html.Substring(monthIndex, html.IndexOf("</month>") - monthIndex); ;
        string day = html.Substring(dayIndex, html.IndexOf("</day>") - dayIndex);
        string hour = html.Substring(hourIndex, html.IndexOf("</hour>") - hourIndex);
        string minite = html.Substring(miniteIndex, html.IndexOf("</minite>") - miniteIndex);
        string second = html.Substring(secondIndex, html.IndexOf("</second>") - secondIndex);
        dt = DateTime.Parse(year + "-" + month + "-" + day + "" + hour + ":" + minite + ":" + second);
    }
    catch (WebException)
    {
        return DateTime.Parse("2011-1-1");
    }
    catch (Exception)
    {
        return DateTime.Parse("2011-1-1");
    }
    finally
    {
        if (wrp != null)
            wrp.Close();
        if (wrt != null)
            wrt.Abort();
    }
    return dt;
}

///<summary>
/// 获取标准北京时间2
///</summary>
///<returns></returns>
publicstatic 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("2011-1-1");
    }
    catch (Exception)
    {
        return DateTime.Parse("2011-1-1");
    }
    finally
    {
        if (wrp != null)
            wrp.Close();
        if (wrt != null)
            wrt.Abort();
    }
    return dt;
}

/// <summary>
/// 获取标准北京时间
/// </summary>
/// <returns></returns>
public static DateTime DataStandardTime()
{
    DateTime dt;

    //返回国际标准时间
    //只使用的时间服务器的IP地址，未使用域名
    try
    {
        string[,] 时间服务器 = new string[14, 2];
        int[] 搜索顺序 = new int[] { 3, 2, 4, 8, 9, 6, 11, 5, 10, 0, 1, 7, 12 };
        时间服务器[0, 0] = "time-a.nist.gov";
        时间服务器[0, 1] = "129.6.15.28";
        时间服务器[1, 0] = "time-b.nist.gov";
        时间服务器[1, 1] = "129.6.15.29";
        时间服务器[2, 0] = "time-a.timefreq.bldrdoc.gov";
        时间服务器[2, 1] = "132.163.4.101";
        时间服务器[3, 0] = "time-b.timefreq.bldrdoc.gov";
        时间服务器[3, 1] = "132.163.4.102";
        时间服务器[4, 0] = "time-c.timefreq.bldrdoc.gov";
        时间服务器[4, 1] = "132.163.4.103";
        时间服务器[5, 0] = "utcnist.colorado.edu";
        时间服务器[5, 1] = "128.138.140.44";
        时间服务器[6, 0] = "time.nist.gov";
        时间服务器[6, 1] = "192.43.244.18";
        时间服务器[7, 0] = "time-nw.nist.gov";
        时间服务器[7, 1] = "131.107.1.10";
        时间服务器[8, 0] = "nist1.symmetricom.com";
        时间服务器[8, 1] = "69.25.96.13";
        时间服务器[9, 0] = "nist1-dc.glassey.com";
        时间服务器[9, 1] = "216.200.93.8";
        时间服务器[10, 0] = "nist1-ny.glassey.com";
        时间服务器[10, 1] = "208.184.49.9";
        时间服务器[11, 0] = "nist1-sj.glassey.com";
        时间服务器[11, 1] = "207.126.98.204";
        时间服务器[12, 0] = "nist1.aol-ca.truetime.com";
        时间服务器[12, 1] = "207.200.81.113";
        时间服务器[13, 0] = "nist1.aol-va.truetime.com";
        时间服务器[13, 1] = "64.236.96.53";
        int portNum = 13;
        string hostName;
        byte[] bytes = new byte[1024];
        int bytesRead = 0;
        System.Net.Sockets.TcpClient client = new System.Net.Sockets.TcpClient();
        for (int i = 0; i < 13; i++)
        {
            hostName = 时间服务器[搜索顺序[i], 1];
            try
            {
                client.Connect(hostName, portNum);
                System.Net.Sockets.NetworkStream ns = client.GetStream();
                bytesRead = ns.Read(bytes, 0, bytes.Length);
                client.Close();
                break;
            }
            catch (System.Exception)
            {
            }
        }
        char[] sp = new char[1];
        sp[0] = ' ';
        dt = new DateTime();
        string str1;
        str1 = System.Text.Encoding.ASCII.GetString(bytes, 0, bytesRead);

        string[] s;
        s = str1.Split(sp);
        if (s.Length >= 2)
        {
            dt = System.DateTime.Parse(s[1] + " " + s[2]);//得到标准时间
            dt = dt.AddHours(8);//得到北京时间*/
        }
        else
        {
            dt = DateTime.Parse("2011-1-1");
        }
    }
    catch (Exception)
    {
        dt = DateTime.Parse("2011-1-1");
    }
    return dt;
}

调用示例：

DateTime dt = Common.GetBeijingTime();// Common.GetStandardTime();
if (dt.ToString() == "2011-1-1 0:00:00")
{
    MessageBox.Show("网络异常，不能启动本程序！");
    Application.Exit();
    return;
}