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 Time protocol described in RFC 868. To use the class, merely establish a connection with
28 * {@link org.apache.commons.net.SocketClient#connect connect } and call either {@link #getTime getTime() } or {@link #getDate getDate() } to retrieve the time,
29 * then call {@link org.apache.commons.net.SocketClient#disconnect disconnect } to close the connection properly.
30 *
31 *
32 * @see TimeUDPClient
33 */
34
35 public final class TimeTCPClient extends SocketClient {
36 /** The default time port. It is set to 37 according to RFC 868. */
37 public static final int DEFAULT_PORT = 37;
38
39 /**
40 * 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.
41 */
42 public static final long SECONDS_1900_TO_1970 = 2208988800L;
43
44 /**
45 * The default TimeTCPClient constructor. It merely sets the default port to <code>DEFAULT_PORT</code>.
46 */
47 public TimeTCPClient() {
48 setDefaultPort(DEFAULT_PORT);
49 }
50
51 /**
52 * Retrieves the time from the server and returns a Java Date containing the time converted to the local time zone.
53 * <p>
54 * The server will have closed the connection at this point, so you should call {@link org.apache.commons.net.SocketClient#disconnect disconnect } after
55 * calling this method. To retrieve another time, you must initiate another connection with {@link org.apache.commons.net.SocketClient#connect connect }
56 * before calling <code>getDate()</code> again.
57 *
58 * @return A Date value containing the time retrieved from the server converted to the local time zone.
59 * @throws IOException If an error occurs while fetching the time.
60 */
61 public Date getDate() throws IOException {
62 return new Date((getTime() - SECONDS_1900_TO_1970) * 1000L);
63 }
64
65 /**
66 * Retrieves 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.
67 * This method reads the raw 32-bit big-endian unsigned integer from the server, converts it to a Java long, and returns the value.
68 * <p>
69 * The server will have closed the connection at this point, so you should call {@link org.apache.commons.net.SocketClient#disconnect disconnect } after
70 * calling this method. To retrieve another time, you must initiate another connection with {@link org.apache.commons.net.SocketClient#connect connect }
71 * before calling <code>getTime()</code> again.
72 *
73 * @return The time value retrieved from the server.
74 * @throws IOException If an error occurs while fetching the time.
75 */
76 public long getTime() throws IOException {
77 final DataInputStream input;
78 input = new DataInputStream(_input_);
79 return input.readInt() & 0xffffffffL;
80 }
81
82 }