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[Java教程]Java代码获取NTP服务器时间


apache的commons-net包下面有ntp相关的实现类,主要类有:

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 org.apache.commons.net.ntp.NTPUDPClient



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 org.apache.commons.net.ntp.TimeInfo



类NTPUDPClient中相关方法:

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 TimeInfo getTime(InetAddress host, int port) throws IOException



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TimeInfo getTime(InetAddress host) throws IOException



    其中,第二个重载方法使用协议规范默认端口:123。

Java代码段:

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  public static void main(String[] args) throws IOException {
  try {
   NTPUDPClient timeClient = new NTPUDPClient();
   String timeServerUrl = "202.120.2.101";
   InetAddress timeServerAddress = InetAddress.getByName(timeServerUrl);
   TimeInfo timeInfo = timeClient.getTime(timeServerAddress);
   TimeStamp timeStamp = timeInfo.getMessage().getTransmitTimeStamp();
   Date date = timeStamp.getDate();
   System.out.println(date);
   DateFormat dateFormat = new SimpleDateFormat("yyyy-MM-dd hh:mm:ss");
   System.out.println(dateFormat.format(date));
  catch (UnknownHostException e) {
   e.printStackTrace();
  }
 }



     运行结果为:

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Thu Dec 03 16:16:50 CST 2015
2015-12-03 04:16:50



附:常用速度较快NTP服务器地址:

ntp.sjtu.edu.cn 202.120.2.101 (上海交通大学网络中心NTP服务器地址下载地址 )

time-a.nist.gov 129.6.15.28 NIST, Gaithersburg, Maryland time-b.nist.gov 129.6.15.29 NIST, Gaithersburg, Maryland time-a.timefreq.bldrdoc.gov 132.163.4.101 NIST, Boulder, Colorado time-b.timefreq.bldrdoc.gov 132.163.4.102 NIST, Boulder, Colorado time-c.timefreq.bldrdoc.gov 132.163.4.103 NIST, Boulder, Colorado