View Javadoc

1   /*
2    * Licensed to the Apache Software Foundation (ASF) under one or more
3    * contributor license agreements.  See the NOTICE file distributed with
4    * this work for additional information regarding copyright ownership.
5    * The ASF licenses this file to You under the Apache License, Version 2.0
6    * (the "License"); you may not use this file except in compliance with
7    * the License.  You may obtain a copy of the License at
8    *
9    *      http://www.apache.org/licenses/LICENSE-2.0
10   *
11   * Unless required by applicable law or agreed to in writing, software
12   * distributed under the License is distributed on an "AS IS" BASIS,
13   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
14   * See the License for the specific language governing permissions and
15   * limitations under the License.
16   */
17  
18  package org.apache.commons.net.time;
19  
20  import java.io.DataInputStream;
21  import java.io.IOException;
22  import java.util.Date;
23  
24  import org.apache.commons.net.SocketClient;
25  
26  /***
27   * The TimeTCPClient class is a TCP implementation of a client for the
28   * Time protocol described in RFC 868.  To use the class, merely
29   * establish a connection with
30   * {@link org.apache.commons.net.SocketClient#connect  connect }
31   * and call either {@link #getTime  getTime() } or
32   * {@link #getDate  getDate() } to retrieve the time, then
33   * call {@link org.apache.commons.net.SocketClient#disconnect  disconnect }
34   * to close the connection properly.
35   * <p>
36   * <p>
37   * @see TimeUDPClient
38   ***/
39  
40  public final class TimeTCPClient extends SocketClient
41  {
42      /*** The default time port.  It is set to 37 according to RFC 868. ***/
43      public static final int DEFAULT_PORT = 37;
44  
45      /***
46       * The number of seconds between 00:00 1 January 1900 and
47       * 00:00 1 January 1970.  This value can be useful for converting
48       * time values to other formats.
49       ***/
50      public static final long SECONDS_1900_TO_1970 = 2208988800L;
51  
52      /***
53       * The default TimeTCPClient constructor.  It merely sets the default
54       * port to <code> DEFAULT_PORT </code>.
55       ***/
56      public TimeTCPClient ()
57      {
58          setDefaultPort(DEFAULT_PORT);
59      }
60  
61      /***
62       * Retrieves the time from the server and returns it.  The time
63       * is the number of seconds since 00:00 (midnight) 1 January 1900 GMT,
64       * as specified by RFC 868.  This method reads the raw 32-bit big-endian
65       * unsigned integer from the server, converts it to a Java long, and
66       * returns the value.
67       * <p>
68       * The server will have closed the connection at this point, so you should
69       * call
70       * {@link org.apache.commons.net.SocketClient#disconnect  disconnect }
71       * after calling this method.  To retrieve another time, you must
72       * initiate another connection with
73       * {@link org.apache.commons.net.SocketClient#connect  connect }
74       * before calling <code> getTime() </code> again.
75       * <p>
76       * @return The time value retrieved from the server.
77       * @exception IOException  If an error occurs while fetching the time.
78       ***/
79      public long getTime() throws IOException
80      {
81          DataInputStream input;
82          input = new DataInputStream(_input_);
83          return (input.readInt() & 0xffffffffL);
84      }
85  
86      /***
87       * Retrieves the time from the server and returns a Java Date
88       * containing the time converted to the local timezone.
89       * <p>
90       * The server will have closed the connection at this point, so you should
91       * call
92       * {@link org.apache.commons.net.SocketClient#disconnect  disconnect }
93       * after calling this method.  To retrieve another time, you must
94       * initiate another connection with
95       * {@link org.apache.commons.net.SocketClient#connect  connect }
96       * before calling <code> getDate() </code> again.
97       * <p>
98       * @return A Date value containing the time retrieved from the server
99       *     converted to the local timezone.
100      * @exception 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