我尝试使用以下代码从公共时间服务器获取时间.
package aaa; import java.util.Arrays; import java.util.List; import org.apache.commons.net.TimeTCPClient; public final class Main { public static java.util.Date getNTPDate() { Listhosts = Arrays.asList("0.pool.ntp.org"); for (String host : hosts) { TimeTCPClient client = new TimeTCPClient(); // We want to timeout if a response takes longer than 5 seconds client.setDefaultTimeout(5000); try { client.connect(host); java.util.Date ntpDate = client.getDate(); client.disconnect(); // Just to be extra caution. if (ntpDate != null) { return ntpDate; } } catch (java.net.SocketException exp) { exp.printStackTrace(); } catch (java.io.IOException exp) { exp.printStackTrace(); } } return null; } public static final void main(String[] args) { System.out.println(getNTPDate()); } }
但是,所有的时间,我都在 java.net.ConnectException: Connection timed out: connect
我试过谷歌几个不同的时间服务器.但是,他们没有工作.我想知道,问题出在我的代码或我选择的服务器上?
NTP是与时间协议不同的协议.NTP服务器仅通过端口UDP/123进行通信.时间服务器使用TCP/37(TimeTCPClient似乎正确实现).
如果您想获得远程时间,请使用适当的服务器(ntp.xs4all.nl
似乎正在侦听时间端口).
您可以使用正确的方法:
import java.io.IOException; import java.net.InetAddress; import java.util.Date; import org.apache.commons.net.ntp.NTPUDPClient; import org.apache.commons.net.ntp.TimeInfo; public final class PublicServerTime { public static Date getNTPDate() { String[] hosts = new String[]{ "ntp02.oal.ul.pt", "ntp04.oal.ul.pt", "ntp.xs4all.nl"}; NTPUDPClient client = new NTPUDPClient(); // We want to timeout if a response takes longer than 5 seconds client.setDefaultTimeout(5000); for (String host : hosts) { try { InetAddress hostAddr = InetAddress.getByName(host); System.out.println("> " + hostAddr.getHostName() + "/" + hostAddr.getHostAddress()); TimeInfo info = client.getTime(hostAddr); Date date = new Date(info.getReturnTime()); return date; } catch (IOException e) { e.printStackTrace(); } } client.close(); return null; } public static final void main(String[] args) { System.out.println(getNTPDate()); }