Passing an id to server socket

Question

Each client contains a fixed id would have as I amnesze that id to the server to then be able to send messages to clients with specific ids?

Server:

    import java.io.IOException;
import java.io.PrintWriter;
import java.net.ServerSocket;
import java.net.Socket;
import java.util.ArrayList;
import java.util.List;
import java.util.Scanner;

public class Server {

    List<PrintWriter> writers = new ArrayList<>();
    List<Thread> clients = new ArrayList<>();
    Thread t;

    public Server() {
        ServerSocket server;
        try {
            server = new ServerSocket(6000);
            while (true) {
                Socket socket = server.accept();
                t = new Thread(new listenClient(socket));
                t.setName(socket.getInetAddress().toString());
                clients.add(t);
                t.start();
                PrintWriter p = new PrintWriter(socket.getOutputStream());
                writers.add(p);
            }
        } catch (IOException e) {
            e.printStackTrace();
        }

    }

    private void sendAll(String text) {
        for (PrintWriter w : writers) {
            w.println(text);
            w.flush();
        }
    }

    private class listenClient implements Runnable {
        Scanner scan;

        public listenClient(Socket socket) {
            try {
            scan = new Scanner(socket.getInputStream());
            } catch (IOException e) {

                e.printStackTrace();
            }
        }

        @Override
        public void run() {
            String text;

            while ((text = scan.nextLine()) != null) {
                sendAll(text);
                System.out.println(text);
            }

        }

    }

    public static void main(String[] args) {
        new Server();

    }

This very simple and as you can see I tried to do something by ip but I realized that it would give conflict more forward and would have to be by id even passed by the client

Answer 1

I’m not sure what the future use of the program is but if each client could enter with a name and you validated that name to never be repeated you had a good "ID" to manage messages.

A few lines of code to set an example to see if you can understand:

    //************ Metodos connetar | isconnect |
        public void Connect() {

            if (!Login.isEmpty()) {
                //message é uma classe onde envio toda a informação que quero enviar
                this.message = new Chatmessage();
                this.message.setAction(Action.CONNECT); //no servidor tenho um "Case" que //consoante a "action" diferente, faz diferentes usos
// exemplos de "action": CONNECT, DISCONNECT, SENDONE,SENDALL;
                this.message.setName(Login);
                this.message.setcodigo(codigo);
                this.socket =connect();

                new Thread(new ListenerSocket(this.socket)).start();

                send(message);
            }

        }

Then on the server I have:

while ((message = (Chatmessage) input.readObject()) != null || stop == false) {
                    Action action = message.getAction();
                    if (action.equals(Action.CONNECT)) {
                        boolean isConnect = connect(message, output);// verifica se o //cliente novo que chegou ao server se pode connetar, se a resposta for "sim" continua no //programa  se a resposta for "nao" o server nao deixa entrar:
                        if (isConnect) {
                            System.out.println(""+ message.getName());
                            if (message.getAdmin()) {
//********************** Guarda os ADMINS                                
                                Admins.put(message.getcodigo(), output);
//********************** Guarda em cada codigo que user é que está logado                            
                                mapUsercodigo.put(message.getcodigo(), message.getName());
//********************** Guarda para cada codigo o socket, que é usado para cada computador
                                mapcodigosOnlines.put(message.getcodigo(), output);
                            } else {
//********************** Guarda os USERS
                                Users.put(message.getcodigo(), output);                            
                                mapcodigo.put(message.getcodigo(), codigo);
                                sendonlines();

                            }    

                        } else {
                            return;
                        }
                    } else if (action.equals(Action.DISCONNECT)) {
                        disconnect(message, output);
                        sendonlines();
                        return;
                    }

This implementation already has many changes but it was practically all created from this excellent tutorial

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