public static void main(String[] args) {
if (args.length == 0) {
System.err.println("Usage: ntp.NTPClient <hostname-or-address-list>");
System.exit(1);
}
NTPUDPClient client = new NTPUDPClient();
// We want to timeout if a response takes longer than 10 seconds
client.setDefaultTimeout(10000);
try {
client.open();
for (String arg : args) {
System.out.println();
try {
InetAddress hostAddr = InetAddress.getByName(arg);
System.out.println("> " + hostAddr.getHostName() + "/" + hostAddr.getHostAddress());
TimeInfo info = client.getTime(hostAddr);
processResponse(info);
} catch (IOException ioe) {
ioe.printStackTrace();
}
}
} catch (SocketException e) {
e.printStackTrace();
}
client.close();
}
public long getOffsetMs() throws SystemTimeManagerException {
NTPUDPClient client = new NTPUDPClient();
client.setDefaultTimeout(GET_OFFSET_DELAY_MS);
try {
client.open();
try {
InetAddress hostAddr = InetAddress.getByName(ntpServer);
TimeInfo info = client.getTime(hostAddr);
return getOffset(info);
} catch (IOException e) {
throw new SystemTimeManagerException(
"Could not get time from " + ntpServer + ", because of " + e.getMessage(), e);
} finally {
client.close();
}
} catch (SocketException e) {
throw new SystemTimeManagerException(
"Could not open socket, because of " + e.getMessage(), e);
}
}
/**
* Queries the given timeserver <code>hostname</code> and returns the time in milliseconds.
*
* @param hostname the timeserver to query
* @return the time in milliseconds or the current time of the system if an error occurs.
*/
protected static long getTime(String hostname) {
try {
NTPUDPClient timeClient = new NTPUDPClient();
timeClient.setDefaultTimeout(NTP_TIMEOUT);
InetAddress inetAddress = InetAddress.getByName(hostname);
TimeInfo timeInfo = timeClient.getTime(inetAddress);
return timeInfo.getReturnTime();
} catch (UnknownHostException uhe) {
logger.warn(
"the given hostname '{}' of the timeserver is unknown -> returning current sytem time instead",
hostname);
} catch (IOException ioe) {
logger.warn(
"couldn't establish network connection [host '{}'] -> returning current sytem time instead",
hostname);
}
return System.currentTimeMillis();
}
