Java tutorial
package beans; /* * Licensed to the Apache Software Foundation (ASF) under one or more * contributor license agreements. See the NOTICE file distributed with * this work for additional information regarding copyright ownership. * The ASF licenses this file to You under the Apache License, Version 2.0 * (the "License"); you may not use this file except in compliance with * the License. You may obtain a copy of the License at * * http://www.apache.org/licenses/LICENSE-2.0 * * Unless required by applicable law or agreed to in writing, software * distributed under the License is distributed on an "AS IS" BASIS, * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. * See the License for the specific language governing permissions and * limitations under the License. */ import java.net.InetAddress; import java.net.UnknownHostException; import java.text.NumberFormat; import org.apache.commons.net.ntp.NtpUtils; import org.apache.commons.net.ntp.NtpV3Packet; import org.apache.commons.net.ntp.TimeInfo; import org.apache.commons.net.ntp.TimeStamp; /*** * This is an example program demonstrating how to use the NTPUDPClient class. * This program sends a Datagram client request packet to a Network time * Protocol (NTP) service port on a specified server, retrieves the time, and * prints it to standard output along with the fields from the NTP message * header (e.g. stratum level, reference id, poll interval, root delay, mode, * ...) See <A HREF="ftp://ftp.rfc-editor.org/in-notes/rfc868.txt"> the * spec </A> for details. * <p> * Usage: NTPClient <hostname-or-address-list> <br> * Example: NTPClient clock.psu.edu * * @author Jason Mathews, MITRE Corp ***/ public final class NTPClient { private static final NumberFormat numberFormat = new java.text.DecimalFormat("0.00"); /** * Process <code>TimeInfo</code> object and print its details. * * @param info * <code>TimeInfo</code> object. */ public static void processResponse(TimeInfo info) { NtpV3Packet message = info.getMessage(); int stratum = message.getStratum(); String refType; if (stratum <= 0) { refType = "(Unspecified or Unavailable)"; } else if (stratum == 1) { refType = "(Primary Reference; e.g., GPS)"; // GPS, radio clock, etc. } else { refType = "(Secondary Reference; e.g. via NTP or SNTP)"; } // stratum should be 0..15... System.out.println(" Stratum: " + stratum + " " + refType); int version = message.getVersion(); int li = message.getLeapIndicator(); System.out.println(" leap=" + li + ", version=" + version + ", precision=" + message.getPrecision()); System.out.println(" mode: " + message.getModeName() + " (" + message.getMode() + ")"); int poll = message.getPoll(); // poll value typically btwn MINPOLL (4) and MAXPOLL (14) System.out.println( " poll: " + (poll <= 0 ? 1 : (int) Math.pow(2, poll)) + " seconds" + " (2 ** " + poll + ")"); double disp = message.getRootDispersionInMillisDouble(); System.out.println(" rootdelay=" + numberFormat.format(message.getRootDelayInMillisDouble()) + ", rootdispersion(ms): " + numberFormat.format(disp)); int refId = message.getReferenceId(); String refAddr = NtpUtils.getHostAddress(refId); String refName = null; if (refId != 0) { if (refAddr.equals("127.127.1.0")) { refName = "LOCAL"; // This is the ref address for the Local Clock } else if (stratum >= 2) { // If reference id has 127.127 prefix then it uses its own reference // clock // defined in the form 127.127.clock-type.unit-num (e.g. 127.127.8.0 // mode 5 // for GENERIC DCF77 AM; see refclock.htm from the NTP software // distribution. if (!refAddr.startsWith("127.127")) { try { InetAddress addr = InetAddress.getByName(refAddr); String name = addr.getHostName(); if (name != null && !name.equals(refAddr)) { refName = name; } } catch (UnknownHostException e) { // some stratum-2 servers sync to ref clock device but fudge stratum // level higher... (e.g. 2) // ref not valid host maybe it's a reference clock name? // otherwise just show the ref IP address. refName = NtpUtils.getReferenceClock(message); } } } else if (version >= 3 && (stratum == 0 || stratum == 1)) { refName = NtpUtils.getReferenceClock(message); // refname usually have at least 3 characters (e.g. GPS, WWV, LCL, etc.) } // otherwise give up on naming the beast... } if (refName != null && refName.length() > 1) { refAddr += " (" + refName + ")"; } System.out.println(" Reference Identifier:\t" + refAddr); TimeStamp refNtpTime = message.getReferenceTimeStamp(); System.out.println(" Reference Timestamp:\t" + refNtpTime + " " + refNtpTime.toDateString()); // Originate Time is time request sent by client (t1) TimeStamp origNtpTime = message.getOriginateTimeStamp(); System.out.println(" Originate Timestamp:\t" + origNtpTime + " " + origNtpTime.toDateString()); long destTime = info.getReturnTime(); // Receive Time is time request received by server (t2) TimeStamp rcvNtpTime = message.getReceiveTimeStamp(); System.out.println(" Receive Timestamp:\t" + rcvNtpTime + " " + rcvNtpTime.toDateString()); // Transmit time is time reply sent by server (t3) TimeStamp xmitNtpTime = message.getTransmitTimeStamp(); System.out.println(" Transmit Timestamp:\t" + xmitNtpTime + " " + xmitNtpTime.toDateString()); // Destination time is time reply received by client (t4) TimeStamp destNtpTime = TimeStamp.getNtpTime(destTime); System.out.println(" Destination Timestamp:\t" + destNtpTime + " " + destNtpTime.toDateString()); info.computeDetails(); // compute offset/delay if not already done Long offsetValue = info.getOffset(); Long delayValue = info.getDelay(); String delay = (delayValue == null) ? "N/A" : delayValue.toString(); String offset = (offsetValue == null) ? "N/A" : offsetValue.toString(); System.out.println(" Roundtrip delay(ms)=" + delay + ", clock offset(ms)=" + offset); // offset // in // ms } public static void main(String[] args) { /* * args=new String[]{"pool.ntp.org"}; * * if (args.length == 0) { System.err.println( * "Usage: 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(); */ // SimpleDateFormat sdf = new SimpleDateFormat("MM/dd/yyyy HH:mm:ss a", // Locale.US); // sdf.setTimeZone(TimeZone.getTimeZone("UTC")); // TimeStamp timestamp = new Network().getNtpRefTime(new String[] { // "pool.ntp.org", "us.pool.ntp.org" }); // System.out.println("------------------------\n" + timestamp + "\n" + // timestamp.getTime() + "\n" + timestamp.toUTCString() + "\n" + // timestamp.getDate() // + "\n" + new Date(timestamp.getTime()) + "\nformated:" + // sdf.format(timestamp.getDate()) + "\n" // + timestamp.toDateString()+"\n-"); } }