Java How to Program Fourth Edition - DCC

Chapter 17 Networking 1035
The MulticastSendingThread constructor (lines 20–26) takes as an argument an
array of bytes containing the message.
1 // MulticastSendingThread.java
2 // MulticastSendingThread is a Thread that broadcasts a chat
3 // message using a multicast datagram.
4 package com.deitel.messenger.sockets.server;
5
6 // Java core packages
7 import java.io.*;
8 import java.net.*;
9
10 // Deitel packages
11 import com.deitel.messenger.sockets.*;
12
13 public class MulticastSendingThread extends Thread
14 implements SocketMessengerConstants {
15
16 // message data
17 private byte[] messageBytes;
18
19 // MulticastSendingThread constructor
20 public MulticastSendingThread( byte[] bytes )
21 {
22 // invoke superclass constructor to name Thread
23 super( "MulticastSendingThread" );
24
25 messageBytes = bytes;
26 }
27
28 // deliver message to MULTICAST_ADDRESS over DatagramSocket
29 public void run()
30 {
31 // deliver message
32 try {
33
34 // create DatagramSocket for sending message
35 DatagramSocket socket =
36 new DatagramSocket( MULTICAST_SENDING_PORT );
37
38 // use InetAddress reserved for multicast group
39 InetAddress group = InetAddress.getByName(
40 MULTICAST_ADDRESS );
41
42 // create DatagramPacket containing message
43 DatagramPacket packet = new DatagramPacket(
44 messageBytes, messageBytes.length, group,
45 MULTICAST_LISTENING_PORT );
46
47 // send packet to multicast group and close socket
48 socket.send( packet );
Fig. Fig. 17.15 17.15 17.15 MulticastSendingThread for delivering outgoing messages to a
multicast group via DatagramPackets.