    View Javadoc
    1   package org.apache.commons.net;
    2
    3   /* ====================================================================
    4    * The Apache Software License, Version 1.1
    5    *
    6    * Copyright (c) 2001 The Apache Software Foundation.  All rights
    7    * reserved.
    8    *
    9    * Redistribution and use in source and binary forms, with or without
    10   * modification, are permitted provided that the following conditions
    11   * are met:
    12   *
    13   * 1. Redistributions of source code must retain the above copyright
    14   *    notice, this list of conditions and the following disclaimer.
    15   *
    16   * 2. Redistributions in binary form must reproduce the above copyright
    17   *    notice, this list of conditions and the following disclaimer in
    18   *    the documentation and/or other materials provided with the
    19   *    distribution.
    20   *
    21   * 3. The end-user documentation included with the redistribution,
    22   *    if any, must include the following acknowledgment:
    23   *       "This product includes software developed by the
    24   *        Apache Software Foundation (http://www.apache.org/)."
    25   *    Alternately, this acknowledgment may appear in the software itself,
    26   *    if and wherever such third-party acknowledgments normally appear.
    27   *
    28   * 4. The names "Apache" and "Apache Software Foundation" and
    29   *    "Apache Commons" must not be used to endorse or promote products
    30   *    derived from this software without prior written permission. For
    31   *    written permission, please contact apache@apache.org.
    32   *
    33   * 5. Products derived from this software may not be called "Apache",
    34   *    nor may "Apache" appear in their name, without
    35   *    prior written permission of the Apache Software Foundation.
    36   *
    37   * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED
    38   * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
    39   * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
    40   * DISCLAIMED.  IN NO EVENT SHALL THE APACHE SOFTWARE FOUNDATION OR
    41   * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
    42   * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
    43   * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
    44   * USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
    45   * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
    46   * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
    47   * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
    48   * SUCH DAMAGE.
    49   * ====================================================================
    50   *
    51   * This software consists of voluntary contributions made by many
    52   * individuals on behalf of the Apache Software Foundation.  For more
    53   * information on the Apache Software Foundation, please see
    54   * <http://www.apache.org/>;.
    55   */
    56
    57  import java.io.IOException;
    58  import java.net.DatagramPacket;
    59  import java.net.InetAddress;
    60  import java.util.Date;
    61
    62  /****
    63   * The TimeUDPClient class is a UDP implementation of a client for the
    64   * Time protocol described in RFC 868.  To use the class, merely
    65   * open a local datagram socket with
    66   * <a href="org.apache.commons.net.DatagramSocketClient.html#open"> open </a>
    67   * and call <a href="#getTime"> getTime </a> or
    68   * <a href="#getTime"> getDate </a> to retrieve the time. Then call
    69   * <a href="org.apache.commons.net.DatagramSocketClient.html#close"> close </a>
    70   * to close the connection properly.  Unlike
    71   * <a href="org.apache.commons.net.TimeTCPClient.html"> TimeTCPClient </a>,
    72   * successive calls to <a href="#getTime"> getTime </a> or
    73   * <a href="#getDate"> getDate </a> are permitted
    74   * without re-establishing a connection.  That is because UDP is a
    75   * connectionless protocol and the Time protocol is stateless.
    76   * <p>
    77   * <p>
    78   * @author Daniel F. Savarese
    79   * @see TimeTCPClient
    80   ***/
    81
    82  public final class TimeUDPClient extends DatagramSocketClient
    83  {
    84      /**** The default time port.  It is set to 37 according to RFC 868. ***/
    85      public static final int DEFAULT_PORT = 37;
    86
    87      /****
    88       * The number of seconds between 00:00 1 January 1900 and
    89       * 00:00 1 January 1970.  This value can be useful for converting
    90       * time values to other formats.
    91       ***/
    92      public static final long SECONDS_1900_TO_1970 = 2208988800L;
    93
    94      private byte[] __dummyData = new byte[1];
    95      private byte[] __timeData = new byte[4];
    96
    97      /****
    98       * Retrieves the time from the specified server and port and
    99       * returns it. The time is the number of seconds since
    100      * 00:00 (midnight) 1 January 1900 GMT, as specified by RFC 868.
    101      * This method reads the raw 32-bit big-endian
    102      * unsigned integer from the server, converts it to a Java long, and
    103      * returns the value.
    104      * <p>
    105      * @param host The address of the server.
    106      * @param port The port of the service.
    107      * @return The time value retrieved from the server.
    108      * @exception IOException If an error occurs while retrieving the time.
    109      ***/
    110     public long getTime(InetAddress host, int port) throws IOException
    111     {
    112         long time;
    113         DatagramPacket sendPacket, receivePacket;
    114
    115         sendPacket =
    116             new DatagramPacket(__dummyData, __dummyData.length, host, port);
    117         receivePacket = new DatagramPacket(__timeData, __timeData.length);
    118
    119         _socket_.send(sendPacket);
    120         _socket_.receive(receivePacket);
    121
    122         time = 0L;
    123         time |= (((__timeData[0] & 0xff) << 24) & 0xffffffffL);
    124         time |= (((__timeData[1] & 0xff) << 16) & 0xffffffffL);
    125         time |= (((__timeData[2] & 0xff) << 8) & 0xffffffffL);
    126         time |= ((__timeData[3] & 0xff) & 0xffffffffL);
    127
    128         return time;
    129     }
    130
    131     /**** Same as <code> getTime(host, DEFAULT_PORT); </code> ***/
    132     public long getTime(InetAddress host) throws IOException
    133     {
    134         return getTime(host, DEFAULT_PORT);
    135     }
    136
    137
    138     /****
    139      * Retrieves the time from the server and returns a Java Date
    140      * containing the time converted to the local timezone.
    141      * <p>
    142      * @param host The address of the server.
    143      * @param port The port of the service.
    144      * @return A Date value containing the time retrieved from the server
    145      *     converted to the local timezone.
    146      * @exception IOException  If an error occurs while fetching the time.
    147      ***/
    148     public Date getDate(InetAddress host, int port) throws IOException
    149     {
    150         return new Date((getTime(host, port) - SECONDS_1900_TO_1970)*1000L);
    151     }
    152
    153
    154     /**** Same as <code> getTime(host, DEFAULT_PORT); </code> ***/
    155     public Date getDate(InetAddress host) throws IOException
    156     {
    157         return new Date((getTime(host, DEFAULT_PORT) -
    158                          SECONDS_1900_TO_1970)*1000L);
    159     }
    160
    161 }
    162

This page was automatically generated by Maven