如何获取Internet时间，或者标准北京时间

[ni871320]

现在我用winform写程序，需要获取网络时间，而不是本地时间，不要用数据库，因为本地机可能没装数据库，请高手帮忙

[wuyq11]

读取http://www.time.ac.cn/stime.asp
http://topic.csdn.net/u/20070223/14/b1f46af6-9995-4276-a9b3-2cc0725f68e6.html

[wuyq11]

webclient,httwebrequest抓取等

[兔子-顾问]

创建一个单独文件粘贴如下代码

using Microsoft.VisualBasic;
using System;
using System.Collections;
using System.Collections.Generic;
using System.Data;
using System.Diagnostics;
using System.IO;
using System.Net;
using System.Net.Sockets;
using System.Runtime.InteropServices;

public class Daytime
{
    //Internet Time Server class by Alastair Dallas 01/27/04

    //Number of seconds
    private const int THRESHOLD_SECONDS = 15;
    // that Windows clock can deviate from NIST and still be okay

    //Server IP addresses from 
    //http://www.boulder.nist.gov/timefreq/service/time-servers.html
    private static string[] Servers = {
		"129.6.15.28",
		"129.6.15.29",
		"132.163.4.101",
		"132.163.4.102",
		"132.163.4.103",
		"128.138.140.44",
		"192.43.244.18",
		"131.107.1.10",
		"66.243.43.21",
		"216.200.93.8",
		"208.184.49.9",
		"207.126.98.204",
		"205.188.185.33"

	};
    public static string LastHost = "";

    public static DateTime LastSysTime;
    public static DateTime GetTime()
    {
        //Returns UTC/GMT using an NIST server if possible, 
        // degrading to simply returning the system clock

        //If we are successful in getting NIST time, then
        // LastHost indicates which server was used and
        // LastSysTime contains the system time of the call
        // If LastSysTime is not within 15 seconds of NIST time,
        //  the system clock may need to be reset
        // If LastHost is "", time is equal to system clock

        string host = null;
        DateTime result = default(DateTime);

        LastHost = "";
        foreach (string host_loopVariable in Servers)
        {
            host = host_loopVariable;
            result = GetNISTTime(host);
            if (result > DateTime.MinValue)
            {
                LastHost = host;
                break; // TODO: might not be correct. Was : Exit For
            }
        }

        if (string.IsNullOrEmpty(LastHost))
        {
            //No server in list was successful so use system time
            result = DateTime.UtcNow;
        }

        return result;
    }

    public static int SecondsDifference(DateTime dt1, DateTime dt2)
    {
        TimeSpan span = dt1.Subtract(dt2);
        return span.Seconds + (span.Minutes * 60) + (span.Hours * 360);
    }

    public static bool WindowsClockIncorrect()
    {
        DateTime nist = GetTime();
        if ((Math.Abs(SecondsDifference(nist, LastSysTime)) > THRESHOLD_SECONDS))
        {
            return true;
        }
        return false;
    }

    private static DateTime GetNISTTime(string host)
    {
        //Returns DateTime.MinValue if host unreachable or does not produce time
        DateTime result = default(DateTime);
        string timeStr = null;

        try
        {
            StreamReader reader = new StreamReader(new TcpClient(host, 13).GetStream());
            LastSysTime = DateTime.UtcNow;
            timeStr = reader.ReadToEnd();
            reader.Close();
        }
        catch (SocketException ex)
        {
            //Couldn't connect to server, transmission error
            Debug.WriteLine("Socket Exception [" + host + "]");
            return DateTime.MinValue;
        }
        catch (Exception ex)
        {
            //Some other error, such as Stream under/overflow
            return DateTime.MinValue;
        }

        //Parse timeStr
        if ((timeStr.Substring(38, 9) != "UTC(NIST)"))
        {
            //This signature should be there
            return DateTime.MinValue;
        }
        if ((timeStr.Substring(30, 1) != "0"))
        {
            //Server reports non-optimum status, time off by as much as 5 seconds
            return DateTime.MinValue;
            //Try a different server
        }

        int jd = int.Parse(timeStr.Substring(1, 5));
        int yr = int.Parse(timeStr.Substring(7, 2));
        int mo = int.Parse(timeStr.Substring(10, 2));
        int dy = int.Parse(timeStr.Substring(13, 2));
        int hr = int.Parse(timeStr.Substring(16, 2));
        int mm = int.Parse(timeStr.Substring(19, 2));
        int sc = int.Parse(timeStr.Substring(22, 2));

        if ((jd < 15020))
        {
            //Date is before 1900
            return DateTime.MinValue;
        }
        if ((jd > 51544))
            yr += 2000;
        else
            yr += 1900;

        return new DateTime(yr, mo, dy, hr, mm, sc);

    }

    [StructLayout(LayoutKind.Sequential)]
    public struct SYSTEMTIME
    {
        public Int16 wYear;
        public Int16 wMonth;
        public Int16 wDayOfWeek;
        public Int16 wDay;
        public Int16 wHour;
        public Int16 wMinute;
        public Int16 wSecond;
        public Int16 wMilliseconds;
    }
    [DllImport("kernel32.dll", CharSet = CharSet.Ansi, SetLastError = true, ExactSpelling = true)]
    private static extern Int32 GetSystemTime(ref SYSTEMTIME stru);
    [DllImport("kernel32.dll", CharSet = CharSet.Ansi, SetLastError = true, ExactSpelling = true)]
    private static extern Int32 SetSystemTime(ref SYSTEMTIME stru);


    public static void SetWindowsClock(DateTime dt)
    {
        //Sets system time. Note: Use UTC time; Windows will apply time zone

        SYSTEMTIME timeStru = default(SYSTEMTIME);
        Int32 result = default(Int32);

        timeStru.wYear = (Int16)dt.Year;
        timeStru.wMonth = (Int16)dt.Month;
        timeStru.wDay = (Int16)dt.Day;
        timeStru.wDayOfWeek = (Int16)dt.DayOfWeek;
        timeStru.wHour = (Int16)dt.Hour;
        timeStru.wMinute = (Int16)dt.Minute;
        timeStru.wSecond = (Int16)dt.Second;
        timeStru.wMilliseconds = (Int16)dt.Millisecond;

        result = SetSystemTime(ref timeStru);

    }
}

调用方法很简单
Daytime.GetTime().ToLocalTime()
就是网络对时后精确的时间。

[天罡gg]

mark

[永动bug制造机]

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