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This article mainly introduces "how Java uses MulticastSocket to achieve group chat applications". In daily operation, I believe many people have doubts about how Java uses MulticastSocket to achieve group chat applications. Xiaobian consulted all kinds of materials and sorted out simple and easy-to-use methods of operation. I hope it will be helpful to answer the questions of "how Java uses MulticastSocket to achieve group chat applications". Next, please follow the editor to study!

MulticastSocket is a (UDP) DatagramSocket with the additional ability to join "groups" of other multicast hosts on the Internet.

Import java.net.*;import java.io.*;import java.util.*; public class GroupChat {private static final String TERMINATE = "Exit"; static String name; static volatile boolean finished = false; public static void main (String [] args) {if (args.length! = 2) System.out.println ("Two arguments required:") Else {try {InetAddress group = InetAddress.getByName (args [0]); int port = Integer.parseInt (args [1]); Scanner sc = new Scanner (System.in); System.out.print ("Enter your name:"); name = sc.nextLine (); MulticastSocket socket = new MulticastSocket (port) / / Since we are deploying socket.setTimeToLive (0); / / this on localhost only (For a subnet set it as 1) socket.joinGroup (group); Thread t = new Thread (new ReadThread (socket, group, port)); / / Spawn a thread for reading messages t.start () / / sent to the current group System.out.println ("Start typing messages...\ n"); while (true) {String message; message = sc.nextLine (); if (message.equalsIgnoreCase (GroupChat.TERMINATE)) {finished = true Socket.leaveGroup (group); socket.close (); break;} message = name + ":" + message; byte [] buffer = message.getBytes (); DatagramPacket datagram = new DatagramPacket (buffer, buffer.length, group, port) Socket.send (datagram);}} catch (SocketException se) {System.out.println ("Error creating socket"); se.printStackTrace ();} catch (IOException ie) {System.out.println ("Error reading/writing from/to socket"); ie.printStackTrace () } class ReadThread implements Runnable {private MulticastSocket socket; private InetAddress group; private int port; private static final int MAX_LEN = 1000; ReadThread (MulticastSocket socket, InetAddress group, int port) {this.socket = socket; this.group = group; this.port = port } @ Override public void run () {while (! GroupChat.finished) {byte [] buffer = new byte [ReadThread.MAX _ LEN]; DatagramPacket datagram = new DatagramPacket (buffer, buffer.length, group, port); String message; try {socket.receive (datagram) Message = new String (buffer, 0, datagram.getLength (), "UTF-8"); if (! message.startsWith (GroupChat.name)) System.out.println (message);} catch (IOException e) {System.out.println ("Socket closed!");}

Save the file as GroupChat.java and compile it using javac, and then run the program with the two command-line arguments specified. The multicast host is specified by a Class D IP address and a standard UDP port number. Class D IP addresses range from 224.0.0.0 to 239.255.255.255 inclusive. The address 224.0.0.0 is reserved and should not be used.

The following is a sample output of the above program:

We use a multicast host with an IP address of 239.0.0.0 and a port number of 1234 (because port numbers 0 to 1023 are reserved). The group has three members: Ironman, CaptainAmerica and Groot. Start all three terminals before sending the message, otherwise the message sent before the terminal is started will be lost (because there is no merge buffer to store the message. ) We need two threads in this application. One is used to accept user input (using the java.util.Scanner class) and the other is used to read messages sent from other clients. Therefore, I separate the thread that performs the read work into the ReadThreadclass. To leave the group, any user can type exit to terminate the session.

The above procedures are performed on a single machine. Socket programming is suitable for distributed programming. The same code snippet meets this requirement when it appears on different machines with Java installed. This is only the most basic service logic. If the front end is developed, the project will be more attractive. You can use Java's AWT (Abstract window Toolkit) or its advanced counterpart Java Swing to develop the front end. Since this is not part of Socket programming, I will remain the same without delving into the details.

Additional points:

You can merge network security functions by performing encryption before sending messages over the network.

Primitive techniques such as Caesar cryptography or advanced methods such as RSA can be used to perform encryption and decryption. You can try using Java's RMI (remote method invocation) to perform the same task.

Here, you can make the most of the abstractions provided by Java. However, if your primary goal is efficiency, then Socket programming is the best choice. Because it does not require any runtime support, it is faster than RMI.

At this point, the study on "how Java uses MulticastSocket to implement group chat applications" is over. I hope to be able to solve your doubts. The collocation of theory and practice can better help you learn, go and try it! If you want to continue to learn more related knowledge, please continue to follow the website, the editor will continue to work hard to bring you more practical articles!

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