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() {
List<String> hosts = 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,我一直在java.net.ConnectException: Connection timed out: connect
我曾尝试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吗?
答案 0 :(得分:10)
NTP是一种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,请使用合适的服务器( ntp.xs4all.nl
似乎正在侦听时间端口)。
答案 1 :(得分:7)
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());
}
答案 2 :(得分:0)
好吧,我可以从我的机器上ping服务器0.pool.ntp.org,是吗?由于超时异常主要是由于运行此代码的机器无法在60秒内连接到主机。
答案 3 :(得分:0)
public class NTPService {
private final static Logger logger = Logger.getLogger(NTPService.class);
private final static int TIMEOUT = 5000;
private final static List<String> hostList =
Arrays.asList("time.windows.com", "nl.pool.ntp.org");
private final NTPUDPClient client = new NTPUDPClient();
public NTPService() {
client.setDefaultTimeout(TIMEOUT);
}
public LocalDateTime getNTPDateTime() {
for (final String host : hostList) {
final LocalDateTime localDateTime = getNTPDateTime(host);
if (null != localDateTime) {
return localDateTime;
}
}
return null;
}
private LocalDateTime getNTPDateTime(final String host) {
try {
client.open();
return convertToLocalDateTime(
TimeStamp.getNtpTime(client.getTime(InetAddress.getByName(host))
.getReturnTime()).getTime());
} catch (final Exception exp) {
logger.warn(String.format("%s: failed to update NTP", host), exp);
return null;
} finally {
if (client.isOpen()) {
client.close();
}
}
}
private LocalDateTime convertToLocalDateTime(final long value) {
return LocalDateTime.ofInstant(Instant.ofEpochMilli(value),
ZoneId.systemDefault());
}
}
用法:
System.out.println(DateTimeFormatter.ofPattern("yyyy.MM.dd HH:mm:ss").
format(new NTPService().getNTPDateTime()));