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    
018    package org.apache.commons.net.time;
019    
020    import java.io.DataInputStream;
021    import java.io.IOException;
022    import java.util.Date;
023    
024    import 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     * <p>
036     * <p>
037     * @author Daniel F. Savarese
038     * @see TimeUDPClient
039     ***/
040    
041    public final class TimeTCPClient extends SocketClient
042    {
043        /*** The default time port.  It is set to 37 according to RFC 868. ***/
044        public static final int DEFAULT_PORT = 37;
045    
046        /***
047         * The number of seconds between 00:00 1 January 1900 and
048         * 00:00 1 January 1970.  This value can be useful for converting
049         * time values to other formats.
050         ***/
051        public static final long SECONDS_1900_TO_1970 = 2208988800L;
052    
053        /***
054         * The default TimeTCPClient constructor.  It merely sets the default
055         * port to <code> DEFAULT_PORT </code>.
056         ***/
057        public TimeTCPClient ()
058        {
059            setDefaultPort(DEFAULT_PORT);
060        }
061    
062        /***
063         * Retrieves the time from the server and returns it.  The time
064         * is the number of seconds since 00:00 (midnight) 1 January 1900 GMT,
065         * as specified by RFC 868.  This method reads the raw 32-bit big-endian
066         * unsigned integer from the server, converts it to a Java long, and
067         * returns the value.
068         * <p>
069         * The server will have closed the connection at this point, so you should
070         * call
071         * {@link org.apache.commons.net.SocketClient#disconnect  disconnect }
072         * after calling this method.  To retrieve another time, you must
073         * initiate another connection with
074         * {@link org.apache.commons.net.SocketClient#connect  connect }
075         * before calling <code> getTime() </code> again.
076         * <p>
077         * @return The time value retrieved from the server.
078         * @exception IOException  If an error occurs while fetching the time.
079         ***/
080        public long getTime() throws IOException
081        {
082            DataInputStream input;
083            input = new DataInputStream(_input_);
084            return (input.readInt() & 0xffffffffL);
085        }
086    
087        /***
088         * Retrieves the time from the server and returns a Java Date
089         * containing the time converted to the local timezone.
090         * <p>
091         * The server will have closed the connection at this point, so you should
092         * call
093         * {@link org.apache.commons.net.SocketClient#disconnect  disconnect }
094         * after calling this method.  To retrieve another time, you must
095         * initiate another connection with
096         * {@link org.apache.commons.net.SocketClient#connect  connect }
097         * before calling <code> getDate() </code> again.
098         * <p>
099         * @return A Date value containing the time retrieved from the server
100         *     converted to the local timezone.
101         * @exception IOException  If an error occurs while fetching the time.
102         ***/
103        public Date getDate() throws IOException
104        {
105            return new Date((getTime() - SECONDS_1900_TO_1970)*1000L);
106        }
107    
108    }
109