String hostname;
int port = DEFAULT_PORT;
if (args.length > 0) {
hostname = args[0];
}
else {
hostname = "tock.usno.navy.mil";
}
if (args.length > 1) {
try {
port = Integer.parseInt(args[1]);
}
catch (NumberFormatException e) {
}
}
// The time protocol sets the epoch at 1900,
// the java Date class at 1970. This number
// converts between them.
long differenceBetweenEpochs = 2208988800L;
// If you'd rather not use the magic number uncomment
// the following section which calculates it directly.
/*
TimeZone gmt = TimeZone.getTimeZone("GMT");
Calendar epoch1900 = Calendar.getInstance(gmt);
epoch1900.set(1900, 01, 01, 00, 00, 00);
long epoch1900ms = epoch1900.getTime().getTime();
Calendar epoch1970 = Calendar.getInstance(gmt);
epoch1970.set(1970, 01, 01, 00, 00, 00);
long epoch1970ms = epoch1970.getTime().getTime();
long differenceInMS = epoch1970ms - epoch1900ms;
long differenceBetweenEpochs = differenceInMS/1000;
*/
InputStream raw = null;
try {
Socket theSocket = new Socket(hostname, port);
raw = theSocket.getInputStream();
long secondsSince1900 = 0;
for (int i = 0; i < 4; i++) {
secondsSince1900 = (secondsSince1900 << 8) | raw.read();
}
long secondsSince1970
= secondsSince1900 - differenceBetweenEpochs;
long msSince1970 = secondsSince1970 * 1000;
Date time = new Date(msSince1970);
System.out.println("It is " + time + " at " + hostname);
} // end try
catch (UnknownHostException e) {
System.err.println(e);
}
catch (IOException e) {
System.err.println(e);
}
finally {
try {
if (raw != null) raw.close();
}
catch (IOException e) {}
}
