    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 *      https://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 Time protocol described in RFC 868. To use the class, merely establish a connection with
    028 * {@link org.apache.commons.net.SocketClient#connect connect} and call either {@link #getTime getTime()} or {@link #getDate getDate()} to retrieve the time,
    029 * then call {@link org.apache.commons.net.SocketClient#disconnect disconnect} to close the connection properly.
    030 *
    031 *
    032 * @see TimeUDPClient
    033 */
    034
    035public final class TimeTCPClient extends SocketClient {
    036    /** The default time port. It is set to 37 according to RFC 868. */
    037    public static final int DEFAULT_PORT = 37;
    038
    039    /**
    040     * 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.
    041     */
    042    public static final long SECONDS_1900_TO_1970 = 2208988800L;
    043
    044    /**
    045     * The default TimeTCPClient constructor. It merely sets the default port to {@code DEFAULT_PORT}.
    046     */
    047    public TimeTCPClient() {
    048        setDefaultPort(DEFAULT_PORT);
    049    }
    050
    051    /**
    052     * Gets the time from the server and returns a Java Date containing the time converted to the local time zone.
    053     * <p>
    054     * The server will have closed the connection at this point, so you should call {@link org.apache.commons.net.SocketClient#disconnect disconnect} after
    055     * calling this method. To retrieve another time, you must initiate another connection with {@link org.apache.commons.net.SocketClient#connect connect}
    056     * before calling {@code getDate()} again.
    057     * </p>
    058     *
    059     * @return A Date value containing the time retrieved from the server converted to the local time zone.
    060     * @throws IOException If an error occurs while fetching the time.
    061     */
    062    public Date getDate() throws IOException {
    063        return new Date((getTime() - SECONDS_1900_TO_1970) * 1000L);
    064    }
    065
    066    /**
    067     * Gets 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.
    068     * This method reads the raw 32-bit big-endian unsigned integer from the server, converts it to a Java long, and returns the value.
    069     * <p>
    070     * The server will have closed the connection at this point, so you should call {@link org.apache.commons.net.SocketClient#disconnect disconnect} after
    071     * calling this method. To retrieve another time, you must initiate another connection with {@link org.apache.commons.net.SocketClient#connect connect}
    072     * before calling {@code getTime()} again.
    073     * </p>
    074     *
    075     * @return The time value retrieved from the server.
    076     * @throws IOException If an error occurs while fetching the time.
    077     */
    078    public long getTime() throws IOException {
    079        final DataInputStream input;
    080        input = new DataInputStream(_input_);
    081        return input.readInt() & 0xffffffffL;
    082    }
    083
    084}