src/java/com/oroinc/net/TimeTCPClient.java

/***
 * $Id: TimeTCPClient.java,v 1.1 2002/04/03 01:04:25 brekke Exp $
 *
 * NetComponents Internet Protocol Library
 * Copyright (C) 1997-2002  Daniel F. Savarese
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2.1 of the License, or (at your option) any later version.
 *
 * This library is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with this library in the LICENSE file; if not, write
 * to the Free Software Foundation, Inc., 59 Temple Place, Suite 330,
 * Boston, MA  02111-1307  USA
 ***/

package com.oroinc.net;

import java.io.*;
import java.net.*;
import java.util.*;

/***
 * The TimeTCPClient class is a TCP implementation of a client for the
 * Time protocol described in RFC 868.  To use the class, merely
 * establish a connection with
 * <a href="com.oroinc.net.SocketClient.html#connect"> connect </a>
 * and call either <a href="#getTime"> getTime() </a> or  
 * <a href="#getDate"> getDate() </a> to retrieve the time, then
 * call <a href="com.oroinc.net.SocketClient.html#disconnect"> disconnect </a>
 * to close the connection properly.
 * <p>
 * <p>
 * @author Daniel F. Savarese
 * @see TimeUDPClient
 ***/

public final class TimeTCPClient extends SocketClient {
  /*** The default time port.  It is set to 37 according to RFC 868. ***/
  public static final int DEFAULT_PORT          = 37;

  /***
   * The number of seconds between 00:00 1 January 1900 and
   * 00:00 1 January 1970.  This value can be useful for converting
   * time values to other formats.
   ***/
  public static final long SECONDS_1900_TO_1970 = 2208988800L;

  /***
   * The default TimeTCPClient constructor.  It merely sets the default
   * port to <code> DEFAULT_PORT </code>.
   ***/
  public TimeTCPClient () {
    setDefaultPort(DEFAULT_PORT);
  }

  /***
   * Retrieves the time from the server and returns it.  The time
   * is the number of seconds since 00:00 (midnight) 1 January 1900 GMT,
   * as specified by RFC 868.  This method reads the raw 32-bit big-endian
   * unsigned integer from the server, converts it to a Java long, and
   * returns the value.  
   * <p>
   * The server will have closed the connection at this point, so you should
   * call
   * <a href="com.oroinc.net.SocketClient.html#disconnect"> disconnect </a>
   * after calling this method.  To retrieve another time, you must
   * initiate another connection with 
   * <a href="com.oroinc.net.SocketClient.html#connect"> connect </a>
   * before calling <code> getTime() </code> again.
   * <p>
   * @return The time value retrieved from the server.
   * @exception IOException  If an error occurs while fetching the time.
   ***/
  public long getTime() throws IOException {
    DataInputStream input;
    input = new DataInputStream(_input_);
    return (long)(input.readInt() & 0xffffffffL);
  }

  /***
   * Retrieves the time from the server and returns a Java Date
   * containing the time converted to the local timezone.
   * <p>
   * The server will have closed the connection at this point, so you should
   * call
   * <a href="com.oroinc.net.SocketClient.html#disconnect"> disconnect </a>
   * after calling this method.  To retrieve another time, you must
   * initiate another connection with 
   * <a href="com.oroinc.net.SocketClient.html#connect"> connect </a>
   * before calling <code> getDate() </code> again.
   * <p>
   * @return A Date value containing the time retrieved from the server
   *     converted to the local timezone.
   * @exception IOException  If an error occurs while fetching the time.
   ***/
  public Date getDate() throws IOException {
    return new Date((getTime() - SECONDS_1900_TO_1970)*1000L);
  }

}