C#获取北京时间与设置系统时间

获取北京时间

public static DateTime GetBeijingTime()
{
    DateTime dt;

    // 返回国际标准时间
    // 只使用 timeServers 的 IP 地址，未使用域名
    try
    {
        string[,] timeServers = new string[14, 2];
        int[] searchOrder = { 3, 2, 4, 8, 9, 6, 11, 5, 10, 0, 1, 7, 12 };
        timeServers[0, 0] = "time-a.nist.gov";
        timeServers[0, 1] = "129.6.15.28";
        timeServers[1, 0] = "time-b.nist.gov";
        timeServers[1, 1] = "129.6.15.29";
        timeServers[2, 0] = "time-a.timefreq.bldrdoc.gov";
        timeServers[2, 1] = "132.163.4.101";
        timeServers[3, 0] = "time-b.timefreq.bldrdoc.gov";
        timeServers[3, 1] = "132.163.4.102";
        timeServers[4, 0] = "time-c.timefreq.bldrdoc.gov";
        timeServers[4, 1] = "132.163.4.103";
        timeServers[5, 0] = "utcnist.colorado.edu";
        timeServers[5, 1] = "128.138.140.44";
        timeServers[6, 0] = "time.nist.gov";
        timeServers[6, 1] = "192.43.244.18";
        timeServers[7, 0] = "time-nw.nist.gov";
        timeServers[7, 1] = "131.107.1.10";
        timeServers[8, 0] = "nist1.symmetricom.com";
        timeServers[8, 1] = "69.25.96.13";
        timeServers[9, 0] = "nist1-dc.glassey.com";
        timeServers[9, 1] = "216.200.93.8";
        timeServers[10, 0] = "nist1-ny.glassey.com";
        timeServers[10, 1] = "208.184.49.9";
        timeServers[11, 0] = "nist1-sj.glassey.com";
        timeServers[11, 1] = "207.126.98.204";
        timeServers[12, 0] = "nist1.aol-ca.truetime.com";
        timeServers[12, 1] = "207.200.81.113";
        timeServers[13, 0] = "nist1.aol-va.truetime.com";
        timeServers[13, 1] = "64.236.96.53";
        int portNum = 13;
        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++)
        {
            string hostName = timeServers[searchOrder[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 (Exception)
            {
                // ignored
            }
        }
        char[] sp = new char[1];
        sp[0] = ' ';
        dt = new DateTime();
        string str1 = System.Text.Encoding.ASCII.GetString(bytes, 0, bytesRead);

        string[] s = str1.Split(sp);
        if (s.Length >= 2)
        {
            dt = 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("2016-1-1");
        }
    }
    catch (Exception)
    {
        dt = DateTime.Parse("2016-1-1");
    }
    return dt;
}            

设置本地系统时间

[DllImport("kernel32.dll")]
private static extern bool SetLocalTime(ref Systemtime time);

[StructLayout(LayoutKind.Sequential)]
private struct Systemtime
{
    public short year;
    public short month;
    public short dayOfWeek;
    public short day;
    public short hour;
    public short minute;
    public short second;
    public short milliseconds;
}

public static bool SetDate(DateTime dt)
{
    Systemtime st;

    st.year = (short)dt.Year;
    st.month = (short)dt.Month;
    st.dayOfWeek = (short)dt.DayOfWeek;
    st.day = (short)dt.Day;
    st.hour = (short)dt.Hour;
    st.minute = (short)dt.Minute;
    st.second = (short)dt.Second;
    st.milliseconds = (short)dt.Millisecond;

    bool rt = SetLocalTime(ref st);
    return rt;
}