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1   /*
2    * Copyright 2001-2005 The Apache Software Foundation
3    *
4    * Licensed under the Apache License, Version 2.0 (the "License");
5    * you may not use this file except in compliance with the License.
6    * You may obtain a copy of the License at
7    *
8    *     http://www.apache.org/licenses/LICENSE-2.0
9    *
10   * Unless required by applicable law or agreed to in writing, software
11   * distributed under the License is distributed on an "AS IS" BASIS,
12   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13   * See the License for the specific language governing permissions and
14   * limitations under the License.
15   */
16  package org.apache.commons.net;
17  
18  import java.io.IOException;
19  import java.util.Date;
20  import java.io.DataInputStream;
21  
22  /***
23   * The TimeTCPClient class is a TCP implementation of a client for the
24   * Time protocol described in RFC 868.  To use the class, merely
25   * establish a connection with
26   * {@link org.apache.commons.net.SocketClient#connect  connect }
27   * and call either {@link #getTime  getTime() } or
28   * {@link #getDate  getDate() } to retrieve the time, then
29   * call {@link org.apache.commons.net.SocketClient#disconnect  disconnect }
30   * to close the connection properly.
31   * <p>
32   * <p>
33   * @author Daniel F. Savarese
34   * @see TimeUDPClient
35   ***/
36  
37  public final class TimeTCPClient extends SocketClient
38  {
39      /*** The default time port.  It is set to 37 according to RFC 868. ***/
40      public static final int DEFAULT_PORT = 37;
41  
42      /***
43       * The number of seconds between 00:00 1 January 1900 and
44       * 00:00 1 January 1970.  This value can be useful for converting
45       * time values to other formats.
46       ***/
47      public static final long SECONDS_1900_TO_1970 = 2208988800L;
48  
49      /***
50       * The default TimeTCPClient constructor.  It merely sets the default
51       * port to <code> DEFAULT_PORT </code>.
52       ***/
53      public TimeTCPClient ()
54      {
55          setDefaultPort(DEFAULT_PORT);
56      }
57  
58      /***
59       * Retrieves the time from the server and returns it.  The time
60       * is the number of seconds since 00:00 (midnight) 1 January 1900 GMT,
61       * as specified by RFC 868.  This method reads the raw 32-bit big-endian
62       * unsigned integer from the server, converts it to a Java long, and
63       * returns the value.
64       * <p>
65       * The server will have closed the connection at this point, so you should
66       * call
67       * {@link org.apache.commons.net.SocketClient#disconnect  disconnect }
68       * after calling this method.  To retrieve another time, you must
69       * initiate another connection with
70       * {@link org.apache.commons.net.SocketClient#connect  connect }
71       * before calling <code> getTime() </code> again.
72       * <p>
73       * @return The time value retrieved from the server.
74       * @exception IOException  If an error occurs while fetching the time.
75       ***/
76      public long getTime() throws IOException
77      {
78          DataInputStream input;
79          input = new DataInputStream(_input_);
80          return (long)(input.readInt() & 0xffffffffL);
81      }
82  
83      /***
84       * Retrieves the time from the server and returns a Java Date
85       * containing the time converted to the local timezone.
86       * <p>
87       * The server will have closed the connection at this point, so you should
88       * call
89       * {@link org.apache.commons.net.SocketClient#disconnect  disconnect }
90       * after calling this method.  To retrieve another time, you must
91       * initiate another connection with
92       * {@link org.apache.commons.net.SocketClient#connect  connect }
93       * before calling <code> getDate() </code> again.
94       * <p>
95       * @return A Date value containing the time retrieved from the server
96       *     converted to the local timezone.
97       * @exception IOException  If an error occurs while fetching the time.
98       ***/
99      public Date getDate() throws IOException
100     {
101         return new Date((getTime() - SECONDS_1900_TO_1970)*1000L);
102     }
103 
104 }
105