001/*
002 * Licensed to the Apache Software Foundation (ASF) under one or more
003 * contributor license agreements.  See the NOTICE file distributed with
004 * this work for additional information regarding copyright ownership.
005 * The ASF licenses this file to You under the Apache License, Version 2.0
006 * (the "License"); you may not use this file except in compliance with
007 * the License.  You may obtain a copy of the License at
008 *
009 *      http://www.apache.org/licenses/LICENSE-2.0
010 *
011 * Unless required by applicable law or agreed to in writing, software
012 * distributed under the License is distributed on an "AS IS" BASIS,
013 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
014 * See the License for the specific language governing permissions and
015 * limitations under the License.
016 */
017
018package org.apache.commons.net.time;
019
020import java.io.DataInputStream;
021import java.io.IOException;
022import java.util.Date;
023
024import org.apache.commons.net.SocketClient;
025
026/***
027 * The TimeTCPClient class is a TCP implementation of a client for the
028 * Time protocol described in RFC 868.  To use the class, merely
029 * establish a connection with
030 * {@link org.apache.commons.net.SocketClient#connect  connect }
031 * and call either {@link #getTime  getTime() } or
032 * {@link #getDate  getDate() } to retrieve the time, then
033 * call {@link org.apache.commons.net.SocketClient#disconnect  disconnect }
034 * to close the connection properly.
035 *
036 *
037 * @see TimeUDPClient
038 ***/
039
040public final class TimeTCPClient extends SocketClient
041{
042    /*** The default time port.  It is set to 37 according to RFC 868. ***/
043    public static final int DEFAULT_PORT = 37;
044
045    /***
046     * The number of seconds between 00:00 1 January 1900 and
047     * 00:00 1 January 1970.  This value can be useful for converting
048     * time values to other formats.
049     ***/
050    public static final long SECONDS_1900_TO_1970 = 2208988800L;
051
052    /***
053     * The default TimeTCPClient constructor.  It merely sets the default
054     * port to <code> DEFAULT_PORT </code>.
055     ***/
056    public TimeTCPClient ()
057    {
058        setDefaultPort(DEFAULT_PORT);
059    }
060
061    /***
062     * Retrieves the time from the server and returns it.  The time
063     * is the number of seconds since 00:00 (midnight) 1 January 1900 GMT,
064     * as specified by RFC 868.  This method reads the raw 32-bit big-endian
065     * unsigned integer from the server, converts it to a Java long, and
066     * returns the value.
067     * <p>
068     * The server will have closed the connection at this point, so you should
069     * call
070     * {@link org.apache.commons.net.SocketClient#disconnect  disconnect }
071     * after calling this method.  To retrieve another time, you must
072     * initiate another connection with
073     * {@link org.apache.commons.net.SocketClient#connect  connect }
074     * before calling <code> getTime() </code> again.
075     *
076     * @return The time value retrieved from the server.
077     * @throws IOException  If an error occurs while fetching the time.
078     ***/
079    public long getTime() throws IOException
080    {
081        DataInputStream input;
082        input = new DataInputStream(_input_);
083        return (input.readInt() & 0xffffffffL);
084    }
085
086    /***
087     * Retrieves the time from the server and returns a Java Date
088     * containing the time converted to the local timezone.
089     * <p>
090     * The server will have closed the connection at this point, so you should
091     * call
092     * {@link org.apache.commons.net.SocketClient#disconnect  disconnect }
093     * after calling this method.  To retrieve another time, you must
094     * initiate another connection with
095     * {@link org.apache.commons.net.SocketClient#connect  connect }
096     * before calling <code> getDate() </code> again.
097     *
098     * @return A Date value containing the time retrieved from the server
099     *     converted to the local timezone.
100     * @throws IOException  If an error occurs while fetching the time.
101     ***/
102    public Date getDate() throws IOException
103    {
104        return new Date((getTime() - SECONDS_1900_TO_1970)*1000L);
105    }
106
107}
108