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