    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        final 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 time zone.
    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 time zone.
    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