Sending and Receiving Messages - TCP/IP Sockets in Java Practical Guide for Programmers - page 57

3. Receive and print out a text-encoded message: lines 15-19

4. Send a binary-encoded message: lines 21-25
Note that before sending, we add 10 cents to the unit price given in the original message.

To demonstrate the use of the encoding and decoding classes with datagrams, we include
a simple UDP sender and receiver. Since this is very similar to the TCP code, we do not include
any code description.

SendUDP.java

0 import java.net.*; // for DatagramSocket, DatagramPacket, and InetAddress
1 import java.io.*;

// for IOException

2
3 public class SendUDP {
4
5

public static void main(String args[]) throws Exception {

6
7

if (args.length != 2 && args.length != 3) // Test for correct # of args

8

throw new IllegalArgumentException("Parameter(s): <Destination>" +

9

" <Port> [<encoding]");

10
11

InetAddress destAddr = InetAddress.getByName(args[0]); // Destination address

12

int destPort = Integer.parseInt(args[1]); // Destination port

13
14

ItemQuote quote = new ItemQuote(1234567890987654L, "5mm Super Widgets",

15

1000, 12999, true, false);

16
17

DatagramSocket sock = new DatagramSocket(); // UDP socket for sending

18
19

ItemQuoteEncoder encoder = (args.length == 3 ?

20 new ItemQuoteEncoderText(args[2]) :

21 new ItemQuoteEncoderText());

22
23 byte[] codedQuote = encoder.encode(quote);

24
25 DatagramPacket message = new DatagramPacket(codedQuote, codedQuote.length,

26 destAddr, destPort);

27 sock.send(message);

28
29

sock.close();

30

}

31 }

SendUDP.java