多线程服务器和客户端Java指定客户端线程

Question

I made a UDP server client architecture with multi-thread the problem is when I send from the server to the client another client thread get the packet and so for all .. how can I specify the thread in which UDP should send back the packet ??

 Client

 public UDPClient(int port) throws SocketException
{
    this.socket = new DatagramSocket();
    this.arg1 = (int) (Math.random() * 1000) ;
    this.arg2 = (int) (Math.random() * 1000) ;
    this.port = port ;
}
    public void run()
{
    try{
        String x = arg1 + " + " + arg2;
        BUFFER = x.getBytes();
        InetAddress ip = InetAddress.getByName("127.0.0.1");
        packet = new DatagramPacket(BUFFER , BUFFER.length,ip,port);
        printOutput(new String("Client send" + x));
        socket.send(packet);
        socket.receive(packet);
        String output = new String(packet.getData(),0,packet.getLength());
        printOutput(new String("receive " + x + "=" + output));
    }
    catch(IOException e)
    {
        System.out.println("UDP sending problem " + e.getMessage());
    }
}

Server

public void run()
{
    while(true)
    {
        try{
            packet = new DatagramPacket(BUFFER,BUFFER.length);
            socket.receive(packet);
            executor.execute(new UDPServerCore(socket,packet,BUFFER));
        }
        catch(IOException e)
        {
            System.out.println("UDP receiving packet problem "
            + e.getMessage());
        }
    }
}

ServerCore

@Override
public void run(){
    String x = new String(packet.getData(),0,packet.getLength());
    String y = parseString(x);
    BUFFER = y.getBytes();
    //packet.setData(y.getBytes());
    DatagramPacket res = new DatagramPacket(BUFFER , BUFFER.length 
    ,packet.getAddress(),packet.getPort());
    try{
    socket.send(res);
    }
    catch(IOException e)
    {
        System.out.println("Something went wrong " + e.getMessage());
    }
}

synchronized private static String parseString(String x )
{
    String arr[] = x.split(" ");
    int z = Integer.parseInt(arr[0]);
    int y = Integer.parseInt(arr[2]);
    y = y + z;
    writeServer.append(x+ "=" + y +"\n");
    return String.valueOf(y);
}

I solved it as the problem was when i created the port of the thread i should have create all the client threads with specified port first then starting each thread.

Answer 1

Y̶o̶u̶ ̶c̶o̶u̶l̶d̶ ̶t̶r̶y̶ ̶t̶o̶ ̶a̶s̶s̶i̶g̶n̶ ̶a̶n̶ ̶I̶D̶ ̶t̶o̶ ̶t̶h̶e̶ ̶p̶a̶c̶k̶e̶t̶ ̶t̶o̶ ̶t̶r̶a̶c̶k̶ ̶t̶h̶e̶ ̶c̶u̶r̶r̶e̶n̶t̶ ̶s̶e̶s̶s̶i̶o̶n̶ ̶i̶t̶ ̶ b̶e̶l̶o̶n̶g̶s̶ ̶t̶o. UDP as opposed to TCP is a no confirmation and no connection protocol. UDP does not support "streams" of data so you have to find a way to dispatch each packet to the corresponding "session handler".

If you could explain more what you're trying to accomplish I think anyone here could help you more.

edit: Each udp packet contains source address and port. You can use those to recognize and store data for every client that connects. Hint: you could use a map / dictionary and when receiving a packet retrieve your session object using client address and port as key