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org.apache.commons.net.TimeUDPClient |
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1 | /* |
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2 | * Copyright 2001-2005 The Apache Software Foundation |
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3 | * |
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4 | * Licensed under the Apache License, Version 2.0 (the "License"); |
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5 | * you may not use this file except in compliance with the License. |
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6 | * You may obtain a copy of the License at |
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7 | * |
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8 | * http://www.apache.org/licenses/LICENSE-2.0 |
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9 | * |
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10 | * Unless required by applicable law or agreed to in writing, software |
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11 | * distributed under the License is distributed on an "AS IS" BASIS, |
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12 | * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
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13 | * See the License for the specific language governing permissions and |
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14 | * limitations under the License. |
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15 | */ |
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16 | package org.apache.commons.net; |
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17 | ||
18 | import java.io.IOException; |
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19 | import java.net.DatagramPacket; |
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20 | import java.net.InetAddress; |
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21 | import java.util.Date; |
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22 | ||
23 | /*** |
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24 | * The TimeUDPClient class is a UDP implementation of a client for the |
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25 | * Time protocol described in RFC 868. To use the class, merely |
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26 | * open a local datagram socket with |
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27 | * {@link org.apache.commons.net.DatagramSocketClient#open open } |
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28 | * and call {@link #getTime getTime } or |
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29 | * {@link #getTime getDate } to retrieve the time. Then call |
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30 | * {@link org.apache.commons.net.DatagramSocketClient#close close } |
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31 | * to close the connection properly. Unlike |
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32 | * {@link org.apache.commons.net.TimeTCPClient}, |
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33 | * successive calls to {@link #getTime getTime } or |
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34 | * {@link #getDate getDate } are permitted |
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35 | * without re-establishing a connection. That is because UDP is a |
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36 | * connectionless protocol and the Time protocol is stateless. |
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37 | * <p> |
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38 | * <p> |
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39 | * @author Daniel F. Savarese |
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40 | * @see TimeTCPClient |
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41 | ***/ |
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42 | ||
43 | 0 | public final class TimeUDPClient extends DatagramSocketClient |
44 | { |
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45 | /*** The default time port. It is set to 37 according to RFC 868. ***/ |
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46 | public static final int DEFAULT_PORT = 37; |
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47 | ||
48 | /*** |
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49 | * The number of seconds between 00:00 1 January 1900 and |
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50 | * 00:00 1 January 1970. This value can be useful for converting |
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51 | * time values to other formats. |
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52 | ***/ |
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53 | public static final long SECONDS_1900_TO_1970 = 2208988800L; |
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54 | ||
55 | 0 | private byte[] __dummyData = new byte[1]; |
56 | 0 | private byte[] __timeData = new byte[4]; |
57 | ||
58 | /*** |
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59 | * Retrieves the time from the specified server and port and |
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60 | * returns it. The time is the number of seconds since |
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61 | * 00:00 (midnight) 1 January 1900 GMT, as specified by RFC 868. |
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62 | * This method reads the raw 32-bit big-endian |
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63 | * unsigned integer from the server, converts it to a Java long, and |
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64 | * returns the value. |
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65 | * <p> |
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66 | * @param host The address of the server. |
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67 | * @param port The port of the service. |
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68 | * @return The time value retrieved from the server. |
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69 | * @exception IOException If an error occurs while retrieving the time. |
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70 | ***/ |
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71 | public long getTime(InetAddress host, int port) throws IOException |
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72 | { |
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73 | long time; |
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74 | DatagramPacket sendPacket, receivePacket; |
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75 | ||
76 | 0 | sendPacket = |
77 | new DatagramPacket(__dummyData, __dummyData.length, host, port); |
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78 | 0 | receivePacket = new DatagramPacket(__timeData, __timeData.length); |
79 | ||
80 | 0 | _socket_.send(sendPacket); |
81 | 0 | _socket_.receive(receivePacket); |
82 | ||
83 | 0 | time = 0L; |
84 | 0 | time |= (((__timeData[0] & 0xff) << 24) & 0xffffffffL); |
85 | 0 | time |= (((__timeData[1] & 0xff) << 16) & 0xffffffffL); |
86 | 0 | time |= (((__timeData[2] & 0xff) << 8) & 0xffffffffL); |
87 | 0 | time |= ((__timeData[3] & 0xff) & 0xffffffffL); |
88 | ||
89 | 0 | return time; |
90 | } |
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91 | ||
92 | /*** Same as <code> getTime(host, DEFAULT_PORT); </code> ***/ |
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93 | public long getTime(InetAddress host) throws IOException |
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94 | { |
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95 | 0 | return getTime(host, DEFAULT_PORT); |
96 | } |
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97 | ||
98 | ||
99 | /*** |
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100 | * Retrieves the time from the server and returns a Java Date |
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101 | * containing the time converted to the local timezone. |
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102 | * <p> |
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103 | * @param host The address of the server. |
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104 | * @param port The port of the service. |
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105 | * @return A Date value containing the time retrieved from the server |
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106 | * converted to the local timezone. |
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107 | * @exception IOException If an error occurs while fetching the time. |
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108 | ***/ |
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109 | public Date getDate(InetAddress host, int port) throws IOException |
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110 | { |
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111 | 0 | return new Date((getTime(host, port) - SECONDS_1900_TO_1970)*1000L); |
112 | } |
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113 | ||
114 | ||
115 | /*** Same as <code> getTime(host, DEFAULT_PORT); </code> ***/ |
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116 | public Date getDate(InetAddress host) throws IOException |
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117 | { |
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118 | 0 | return new Date((getTime(host, DEFAULT_PORT) - |
119 | SECONDS_1900_TO_1970)*1000L); |
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120 | } |
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121 | ||
122 | } |
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123 |
This report is generated by jcoverage, Maven and Maven JCoverage Plugin. |