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    1   /*
    2    * Copyright 2001-2005 The Apache Software Foundation
    3    *
    4    * Licensed under the Apache License, Version 2.0 (the "License");
    5    * you may not use this file except in compliance with the License.
    6    * You may obtain a copy of the License at
    7    *
    8    *     http://www.apache.org/licenses/LICENSE-2.0
    9    *
    10   * Unless required by applicable law or agreed to in writing, software
    11   * distributed under the License is distributed on an "AS IS" BASIS,
    12   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    13   * See the License for the specific language governing permissions and
    14   * limitations under the License.
    15   */
    16  package org.apache.commons.net;
    17
    18  import java.io.IOException;
    19  import java.util.Date;
    20  import java.io.DataInputStream;
    21
    22  /****
    23   * The TimeTCPClient class is a TCP implementation of a client for the
    24   * Time protocol described in RFC 868.  To use the class, merely
    25   * establish a connection with
    26   * {@link org.apache.commons.net.SocketClient#connect  connect }
    27   * and call either {@link #getTime  getTime() } or
    28   * {@link #getDate  getDate() } to retrieve the time, then
    29   * call {@link org.apache.commons.net.SocketClient#disconnect  disconnect }
    30   * to close the connection properly.
    31   * <p>
    32   * <p>
    33   * @author Daniel F. Savarese
    34   * @see TimeUDPClient
    35   ***/
    36
    37  public final class TimeTCPClient extends SocketClient
    38  {
    39      /**** The default time port.  It is set to 37 according to RFC 868. ***/
    40      public static final int DEFAULT_PORT = 37;
    41
    42      /****
    43       * The number of seconds between 00:00 1 January 1900 and
    44       * 00:00 1 January 1970.  This value can be useful for converting
    45       * time values to other formats.
    46       ***/
    47      public static final long SECONDS_1900_TO_1970 = 2208988800L;
    48
    49      /****
    50       * The default TimeTCPClient constructor.  It merely sets the default
    51       * port to <code> DEFAULT_PORT </code>.
    52       ***/
    53      public TimeTCPClient ()
    54      {
    55          setDefaultPort(DEFAULT_PORT);
    56      }
    57
    58      /****
    59       * Retrieves the time from the server and returns it.  The time
    60       * is the number of seconds since 00:00 (midnight) 1 January 1900 GMT,
    61       * as specified by RFC 868.  This method reads the raw 32-bit big-endian
    62       * unsigned integer from the server, converts it to a Java long, and
    63       * returns the value.
    64       * <p>
    65       * The server will have closed the connection at this point, so you should
    66       * call
    67       * {@link org.apache.commons.net.SocketClient#disconnect  disconnect }
    68       * after calling this method.  To retrieve another time, you must
    69       * initiate another connection with
    70       * {@link org.apache.commons.net.SocketClient#connect  connect }
    71       * before calling <code> getTime() </code> again.
    72       * <p>
    73       * @return The time value retrieved from the server.
    74       * @exception IOException  If an error occurs while fetching the time.
    75       ***/
    76      public long getTime() throws IOException
    77      {
    78          DataInputStream input;
    79          input = new DataInputStream(_input_);
    80          return (long)(input.readInt() & 0xffffffffL);
    81      }
    82
    83      /****
    84       * Retrieves the time from the server and returns a Java Date
    85       * containing the time converted to the local timezone.
    86       * <p>
    87       * The server will have closed the connection at this point, so you should
    88       * call
    89       * {@link org.apache.commons.net.SocketClient#disconnect  disconnect }
    90       * after calling this method.  To retrieve another time, you must
    91       * initiate another connection with
    92       * {@link org.apache.commons.net.SocketClient#connect  connect }
    93       * before calling <code> getDate() </code> again.
    94       * <p>
    95       * @return A Date value containing the time retrieved from the server
    96       *     converted to the local timezone.
    97       * @exception IOException  If an error occurs while fetching the time.
    98       ***/
    99      public Date getDate() throws IOException
    100     {
    101         return new Date((getTime() - SECONDS_1900_TO_1970)*1000L);
    102     }
    103
    104 }
    105