这是一个示例-
尚不完整，但应使您了解如何将输出多播到许多侦听客户端。有更好的方法来执行此操作，但是我写的类似于您执行套接字的方式。它还在许多地方都缺少错误检查，因此我将其留给读者练习。还编写了此代码，以便可以在Java
1.6或更高版本上使用。
该代码使用Server对象中维护的已连接客户端的列表。从一个客户端收到输入时，输出将多播到“客户端”列表中的每个客户端。编写是通过Client类中的write方法完成的。
import java.io.BufferedReader;import java.io.IOException;import java.io.InputStreamReader;import java.io.PrintWriter;import java.net.ServerSocket;import java.net.Socket;import java.util.linkedList;import java.util.Iterator;import java.util.List;import java.util.concurrent.ExecutorService;import java.util.concurrent.Executors;public class MulticastEchoServer { List<Client> clientList = new linkedList<Client>(); ExecutorService executor; int port = 40480; int max = 10; public MulticastEchoServer() { this.executor = Executors.newFixedThreadPool(max); } public void writeToAllClients(String string) throws IOException { // Multiple threads access this so it must be in synchronized block synchronized (this.clientList) { Iterator<Client> iter = this.clientList.iterator(); while (iter.hasNext()) iter.next().write(string); } } public void addClient(Client client) { // Multiple threads access this so it must be in synchronized block synchronized (this.clientList) { clientList.add(client); } } public void removeClient(Client client) { // Multiple threads access this so it must be in synchronized block synchronized (this.clientList) { clientList.remove(client); } } public void listen() { try { ServerSocket server = new ServerSocket(port); System.out.println("server started and listening for connections"); while (true) { try { Socket socket = server.accept(); System.out.print("connection accepted" + "n"); Client newClient = new Client(this, socket); this.addClient(newClient); this.executor.execute(newClient); } catch (IOException e) { e.printStackTrace(); } } } catch (Exception e) { e.printStackTrace(); } } public static void main(String[] args) { new MulticastEchoServer().listen(); } private class Client implements Runnable { Socket socket; PrintWriter writer; BufferedReader reader; MulticastEchoServer server; public Client(MulticastEchoServer server, Socket socket) throws IOException { this.server = server; this.socket = socket; this.writer = new PrintWriter(this.socket.getOutputStream()); this.reader = new BufferedReader(new InputStreamReader(socket.getInputStream())); } synchronized public void write(String string) throws IOException { writer.write(string); writer.flush(); } public void close() { this.writer.close(); try { this.reader.close(); } catch (IOException e) { } try { this.socket.close(); } catch (IOException e) { } } @Override public void run() { System.out.println("Client Waiting"); String inString = null; try { while ((inString = this.reader.readLine()) != null) { this.server.writeToAllClients(inString + "n"); System.out.println(inString); } } catch (IOException e1) { } server.removeClient(this); this.close(); System.out.println("Client Closed"); } }}
