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16 package org.apache.commons.net;
17
18 import java.io.IOException;
19 import java.net.DatagramPacket;
20 import java.net.InetAddress;
21
22 /***
23 * The EchoUDPClient class is a UDP implementation of a client for the
24 * Echo protocol described in RFC 862. To use the class,
25 * just open a local UDP port
26 * with {@link org.apache.commons.net.DatagramSocketClient#open open }
27 * and call {@link #send send } to send datagrams to the server,
28 * then call {@link #receive receive } to receive echoes.
29 * After you're done echoing data, call
30 * {@link org.apache.commons.net.DatagramSocketClient#close close() }
31 * to clean up properly.
32 * <p>
33 * <p>
34 * @author Daniel F. Savarese
35 * @see EchoTCPClient
36 * @see DiscardUDPClient
37 ***/
38
39 public final class EchoUDPClient extends DiscardUDPClient
40 {
41 /*** The default echo port. It is set to 7 according to RFC 862. ***/
42 public static final int DEFAULT_PORT = 7;
43
44 private DatagramPacket __receivePacket = new DatagramPacket(new byte[0], 0);
45
46 /***
47 * Sends the specified data to the specified server at the default echo
48 * port.
49 * <p>
50 * @param data The echo data to send.
51 * @param length The length of the data to send. Should be less than
52 * or equal to the length of the data byte array.
53 * @param host The address of the server.
54 * @exception IOException If an error occurs during the datagram send
55 * operation.
56 ***/
57 public void send(byte[] data, int length, InetAddress host)
58 throws IOException
59 {
60 send(data, length, host, DEFAULT_PORT);
61 }
62
63
64 /*** Same as <code> send(data, data.length, host) </code> ***/
65 public void send(byte[] data, InetAddress host) throws IOException
66 {
67 send(data, data.length, host, DEFAULT_PORT);
68 }
69
70
71 /***
72 * Receives echoed data and returns its length. The data may be divided
73 * up among multiple datagrams, requiring multiple calls to receive.
74 * Also, the UDP packets will not necessarily arrive in the same order
75 * they were sent.
76 * <p>
77 * @return Length of actual data received.
78 * @exception IOException If an error occurs while receiving the data.
79 ***/
80 public int receive(byte[] data, int length) throws IOException
81 {
82 __receivePacket.setData(data);
83 __receivePacket.setLength(length);
84 _socket_.receive(__receivePacket);
85 return __receivePacket.getLength();
86 }
87
88 /*** Same as <code> receive(data, data.length)</code> ***/
89 public int receive(byte[] data) throws IOException
90 {
91 return receive(data, data.length);
92 }
93
94 }
95