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1 package org.apache.commons.net; 2 3 /* ==================================================================== 4 * The Apache Software License, Version 1.1 5 * 6 * Copyright (c) 2001 The Apache Software Foundation. All rights 7 * reserved. 8 * 9 * Redistribution and use in source and binary forms, with or without 10 * modification, are permitted provided that the following conditions 11 * are met: 12 * 13 * 1. Redistributions of source code must retain the above copyright 14 * notice, this list of conditions and the following disclaimer. 15 * 16 * 2. Redistributions in binary form must reproduce the above copyright 17 * notice, this list of conditions and the following disclaimer in 18 * the documentation and/or other materials provided with the 19 * distribution. 20 * 21 * 3. The end-user documentation included with the redistribution, 22 * if any, must include the following acknowledgment: 23 * "This product includes software developed by the 24 * Apache Software Foundation (http://www.apache.org/)." 25 * Alternately, this acknowledgment may appear in the software itself, 26 * if and wherever such third-party acknowledgments normally appear. 27 * 28 * 4. The names "Apache" and "Apache Software Foundation" and 29 * "Apache Commons" must not be used to endorse or promote products 30 * derived from this software without prior written permission. For 31 * written permission, please contact apache@apache.org. 32 * 33 * 5. Products derived from this software may not be called "Apache", 34 * nor may "Apache" appear in their name, without 35 * prior written permission of the Apache Software Foundation. 36 * 37 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED 38 * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 39 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE 40 * DISCLAIMED. IN NO EVENT SHALL THE APACHE SOFTWARE FOUNDATION OR 41 * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, 42 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT 43 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF 44 * USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND 45 * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, 46 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT 47 * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 48 * SUCH DAMAGE. 49 * ==================================================================== 50 * 51 * This software consists of voluntary contributions made by many 52 * individuals on behalf of the Apache Software Foundation. For more 53 * information on the Apache Software Foundation, please see 54 * <http://www.apache.org/>;. 55 */ 56 57 import java.io.IOException; 58 import java.net.DatagramPacket; 59 import java.net.InetAddress; 60 61 /**** 62 * The DaytimeUDPClient class is a UDP implementation of a client for the 63 * Daytime protocol described in RFC 867. To use the class, merely 64 * open a local datagram socket with 65 * <a href="org.apache.commons.net.DatagramSocketClient.html#open"> open </a> 66 * and call <a href="#getTime"> getTime </a> to retrieve the daytime 67 * string, then 68 * call <a href="org.apache.commons.net.DatagramSocketClient.html#close"> close </a> 69 * to close the connection properly. Unlike 70 * <a href="org.apache.commons.net.DaytimeTCPClient.html"> DaytimeTCPClient </a>, 71 * successive calls to <a href="#getTime"> getTime </a> are permitted 72 * without re-establishing a connection. That is because UDP is a 73 * connectionless protocol and the Daytime protocol is stateless. 74 * <p> 75 * <p> 76 * @author Daniel F. Savarese 77 * @see DaytimeTCPClient 78 ***/ 79 80 public final class DaytimeUDPClient extends DatagramSocketClient 81 { 82 /**** The default daytime port. It is set to 13 according to RFC 867. ***/ 83 public static final int DEFAULT_PORT = 13; 84 85 private byte[] __dummyData = new byte[1]; 86 // Received dates should be less than 256 bytes 87 private byte[] __timeData = new byte[256]; 88 89 /**** 90 * Retrieves the time string from the specified server and port and 91 * returns it. 92 * <p> 93 * @param host The address of the server. 94 * @param port The port of the service. 95 * @return The time string. 96 * @exception IOException If an error occurs while retrieving the time. 97 ***/ 98 public String getTime(InetAddress host, int port) throws IOException 99 { 100 DatagramPacket sendPacket, receivePacket; 101 102 sendPacket = 103 new DatagramPacket(__dummyData, __dummyData.length, host, port); 104 receivePacket = new DatagramPacket(__timeData, __timeData.length); 105 106 _socket_.send(sendPacket); 107 _socket_.receive(receivePacket); 108 109 return new String(receivePacket.getData(), 0, receivePacket.getLength()); 110 } 111 112 /**** Same as <code>getTime(host, DaytimeUDPClient.DEFAULT_PORT);</code> ***/ 113 public String getTime(InetAddress host) throws IOException 114 { 115 return getTime(host, DEFAULT_PORT); 116 } 117 118 } 119

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