如何分组2个udp客户？

问题描述

我想做的是第2组客户，并使他们彼此交流。因此，如果连接了2个客户端，则它们只能彼此通信；如果连接了第三个客户端，则它将无法与其他2个客户端通信，但它将创建另一个由2个客户端组成的组，依此类推...正确现在，如果客户端发送一条消息，它将发送给所有客户端，但是我不知道如何使它像上述那样工作。通过在控制台中键入内容来从客户端发送消息。

服务器：

public class Server extends Thread{

public final static int PORT = 7331;
private final static int BUFFER = 1024;

private DatagramSocket socket;
private ArrayList<InetAddress> clientAddresses;
private ArrayList<Integer> clientPorts;
private HashSet<String> existingClients;

public Server() throws IOException {
    socket = new DatagramSocket(PORT);
    System.out.println("[SERVER] UDP server successfully launched on port " + PORT);
    
    clientAddresses = new ArrayList<InetAddress>();
    clientPorts = new ArrayList<Integer>();
    existingClients = new HashSet<String>();
}

public void run() {
    byte[] buf = new byte[BUFFER];
    while (true) {
        try {
            //resets buffer so only new messages get displayed
            Arrays.fill(buf,(byte) 0);
            
            DatagramPacket packet = new DatagramPacket(buf,buf.length);
            socket.receive(packet);

            String content = new String(buf,buf.length);

            InetAddress clientAddress = packet.getAddress();
            int clientPort = packet.getPort();

            String id = clientAddress.toString() + "," + clientPort;
            if (!existingClients.contains(id)) {
                existingClients.add(id);
                clientPorts.add(clientPort);
                clientAddresses.add(clientAddress);
            }

            System.out.println(id + " : " + content);
            byte[] data = (id + " : " + content).getBytes();
            for (int i = 0; i < clientAddresses.size(); i++) {
                InetAddress cl = clientAddresses.get(i);
                int cp = clientPorts.get(i);
                packet = new DatagramPacket(data,data.length,cl,cp);
                socket.send(packet);
            }
        } catch (Exception e) {
            System.err.println(e);
        }
    }
}

public static void main(String args[]) throws Exception {
    Server s = new Server();
    s.start();
}
}

客户：

public class Client implements Runnable {

public static void main(String args[]) throws Exception {
    String host = "127.0.0.1";

    DatagramSocket socket = new DatagramSocket();
    
    //handles the receiving part for every client (incoming packets to clients)
    MessageReceiver r = new MessageReceiver(socket);
    
    Client s = new Client(socket,host);
    Thread rt = new Thread(r);
    Thread st = new Thread(s);
    rt.start();
    st.start();
}



public final static int PORT = 7331;
private DatagramSocket sock;
private String hostname;

Client(DatagramSocket s,String h) {
    sock = s;
    hostname = h;
}

//sending clients socket to server
private void sendMessage(String s) throws Exception {
    //getting bytes from message
    byte buf[] = s.getBytes();
    
    //getting hostname from server
    InetAddress address = InetAddress.getByName(hostname);
    
    //setting up packet
    DatagramPacket packet = new DatagramPacket(buf,buf.length,address,PORT);
    
    //sending packet to server
    sock.send(packet);
}

public void run() {
    //connected boolean is used to send a greetings message once for every new client that has joined
    boolean connected = false;
    
    do {
        try {
            sendMessage("GREETINGS");
            connected = true;
        } catch (Exception e) {

        }
    } while (!connected);
    
    //reads from the console
    BufferedReader in = new BufferedReader(new InputStreamReader(system.in));
    
    while (true) {
        try {
            while (!in.ready()) {
                Thread.sleep(100);
            }
            
            //sends message from console to server
            sendMessage(in.readLine());
        } catch (Exception e) {
            System.err.println(e);
        }
    }
}
}

//this class handles receiving part of clients
class MessageReceiver implements Runnable {
DatagramSocket sock;
byte buf[];

MessageReceiver(DatagramSocket s) {
    sock = s;
    buf = new byte[1024];
}

public void run() {
    while (true) {
        try {
            DatagramPacket packet = new DatagramPacket(buf,buf.length);
            sock.receive(packet);
            String received = new String(packet.getData(),packet.getLength());
            System.out.println(received);
        } catch (Exception e) {
            System.err.println(e);
        }
    }
}
}

解决方法

您要尝试的是消息广播或消息中继器客户端。 广播是在网络层上实现的（使用brodcast本地网络广播地址）。

如果以这种方式实现，则当您拥有两个以上的客户端时，您将淹没网络。最好的问候您的网络管理员。 ;-）