DatagramChannel channel = null;
try {
channel = DatagramChannel.open();
// port 0 selects any available port
SocketAddress address = new InetSocketAddress(0);
DatagramSocket socket = channel.socket();
socket.setSoTimeout(5000);
socket.bind(address);
SocketAddress server = new InetSocketAddress("time.nist.gov", 37);
ByteBuffer buffer = ByteBuffer.allocate(8192);
// time protocol always uses big-endian order
buffer.order(ByteOrder.BIG_ENDIAN);
// Must put at least one byte of data in the buffer;
// it doesn't matter what it is.
buffer.put((byte) 65);
buffer.flip();
channel.send(buffer, server);
buffer.clear();
buffer.put((byte) 0).put((byte) 0).put((byte) 0).put((byte) 0);
channel.receive(buffer);
buffer.flip();
long secondsSince1900 = buffer.getLong();
// The time protocol sets the epoch at 1900,
// the java.util.Date class at 1970. This number
// converts between them.
long differenceBetweenEpochs = 2208988800L;
long secondsSince1970
= secondsSince1900 - differenceBetweenEpochs;
long msSince1970 = secondsSince1970 * 1000;
Date time = new Date(msSince1970);
System.out.println(time);
}
catch (Exception ex) {
System.err.println(ex);
ex.printStackTrace();
}
finally {
if (channel != null) channel.close();
}
