多播组客户端没有收到来自服务器的消息

Question

我创建了一个聊天应用程序来将消息发送到与多个客户端的多播组对话。

消息必须发送到 MulticastServer 并发送到多播组上的所有客户端。此时，消息从客户端完美地到达服务器。

但是当我回复客户端（即使是一个简单的字符串）时，消息只发送给发送消息的客户端，而不是发送给多播组中的所有用户。

StackTrace 没有给我任何错误，但我仍然遇到这个问题。

我给你一些重要的代码。以下是与多播服务器的连接。 DEFAULT_ADRESS 是 224.0.0.3.

    socket = new MulticastSocket();
    address = InetAddress.getByName(DEFAULT_ADRESS);
    socket.joinGroup(address);

向 MulticastServer 发送消息的代码部分：

String messtoSendServer = utilizadorOnline.getNome() + ":" + textfieldtocomunicateGroupe.getText();

        buf = messtoSendServer.getBytes();

        packet = new DatagramPacket(buf, buf.length, address, DEFAULT_PORT);

        try {
            // userOnline_Multicast.getSocketMulti().send(packet);
            socket.send(packet);

        } catch (IOException ex) {
            Logger.getLogger(ConversaGrupo.class.getName()).log(Level.SEVERE, null, ex);
        }

从服务器接收消息的代码部分：

  private void receberDadosServidor() throws IOException {



            try {

                DatagramPacket packet1 = new DatagramPacket(buf, buf.length);

                socket.receive(packet1);

                String received = new String(packet1.getData());

                textareatoGroupChat.setText(textareatoGroupChat.getText() + "\n" + received);

            } catch (IOException ex) {

                Logger.getLogger(ConversaGrupo.class.getName()).log(Level.SEVERE, null, ex);
                socket.close();
                socket.leaveGroup(address);
            }

这是服务器端。首先启动线程：

 public void run(JTextArea txtArea) throws IOException {


       new MulticastServerThread(txtArea).start();
    }

还有线程本身：

public class MulticastServerThread extends Thread {

    private final String DEFAULT_MULTICASTIP = "224.0.0.3";
    private final int DEFAULT_MULTICASTPORT = 4446;
    private final int FIVE_SECONDS =5000;
    private DatagramPacket packet;
    private JTextArea textA;
    private boolean moreQuotes = true;
    private MulticastSocket socket = null;

    private InetAddress adresstoConnectMulticast = null;

    public MulticastServerThread(JTextArea txt) throws IOException {
        super("MulticastServerThread");
        this.textA = txt;

    }

    @Override
    public void run() {

        while (true) {
            try {
                byte[] buf = new byte[1024];

                socket = new MulticastSocket(DEFAULT_MULTICASTPORT);
                adresstoConnectMulticast = InetAddress.getByName(DEFAULT_MULTICASTIP);

                socket.joinGroup(adresstoConnectMulticast);

                packet = new DatagramPacket(buf, buf.length, adresstoConnectMulticast, DEFAULT_MULTICASTPORT); //usado para receber um datagram do socket, o array de bytes contem dados do cliente especifico

                socket.receive(packet);

                String mensagem = new String(packet.getData()).trim();

                textA.setText(textA.getText() + "\n\nServer Multicast Receive from User:" + mensagem +" on IP Multicast " +DEFAULT_MULTICASTIP +" | "+ DEFAULT_MULTICASTPORT);

                buf = mensagem.getBytes();
                InetAddress ed = packet.getAddress();
                int portad = packet.getPort();

//manda de volta para o cliente.
                packet = new DatagramPacket(buf, buf.length, ed, portad);
                socket.send(packet);

                try {

                    sleep((long) Math.random() * FIVE_SECONDS);
                } catch (InterruptedException e) {
                }

            } catch (IOException ex) {
                Logger.getLogger(MulticastServerThread.class.getName()).log(Level.SEVERE, null, ex);
                socket.close();

            }

        }
    }
}

Answer 1

这里有几个问题。

socket = new MulticastSocket();

您的客户端都需要绑定到同一个端口。向构造函数提供固定端口号。否则你会得到一个系统分配的端口。

其次，您的服务器回复源的IP地址和端口号。回复群IP地址和源端口号，或者上面的固定端口号，应该是一样的。

三、224.0.0.3保留。你不能使用它。

并保持服务器的套接字打开。不要每次都循环打开和关闭它。

多播组客户端没有收到来自服务器的消息

Multicast group clients doesn't receive the message from server

java

udp

multicast