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 * https://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
37 /** The default time port. It is set to 37 according to RFC 868. */
38 public static final int DEFAULT_PORT = 37;
39
40 /**
41 * 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.
42 */
43 public static final long SECONDS_1900_TO_1970 = 2208988800L;
44
45 /**
46 * The default TimeTCPClient constructor. It merely sets the default port to {@code DEFAULT_PORT}.
47 */
48 public TimeTCPClient() {
49 setDefaultPort(DEFAULT_PORT);
50 }
51
52 /**
53 * Gets the time from the server and returns a Java Date containing the time converted to the local time zone.
54 * <p>
55 * The server will have closed the connection at this point, so you should call {@link org.apache.commons.net.SocketClient#disconnect disconnect} after
56 * calling this method. To retrieve another time, you must initiate another connection with {@link org.apache.commons.net.SocketClient#connect connect}
57 * before calling {@code getDate()} again.
58 * </p>
59 *
60 * @return A Date value containing the time retrieved from the server converted to the local time zone.
61 * @throws IOException If an error occurs while fetching the time.
62 */
63 public Date getDate() throws IOException {
64 return new Date((getTime() - SECONDS_1900_TO_1970) * 1000L);
65 }
66
67 /**
68 * Gets 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.
69 * This method reads the raw 32-bit big-endian unsigned integer from the server, converts it to a Java long, and returns the value.
70 * <p>
71 * The server will have closed the connection at this point, so you should call {@link org.apache.commons.net.SocketClient#disconnect disconnect} after
72 * calling this method. To retrieve another time, you must initiate another connection with {@link org.apache.commons.net.SocketClient#connect connect}
73 * before calling {@code getTime()} again.
74 * </p>
75 *
76 * @return The time value retrieved from the server.
77 * @throws IOException If an error occurs while fetching the time.
78 */
79 public long getTime() throws IOException {
80 final DataInputStream input;
81 input = new DataInputStream(_input_);
82 return input.readInt() & 0xffffffffL;
83 }
84
85 }