Connecting two clients via server java

Question

Hi guys i'm trying to connect two clients via the server, atm each client cconnects to the server and creates a new thread so each client can communicate with the server, but how would I get two clients communicating via the server ?

Server:

public void allowConnections(){
    int i = 0;
    try{
        while(true){                                                      
            new Thread(new TestT(draughtsSS.accept(),i )).start();         //listen for incoming connections    
            i++;
        }
    }
    catch(IOException e){
        System.out.println("Error :"+e.getMessage());
    }   
}


class TestT implements Runnable{

    Socket s;
    int gameNo;
    Scanner in;
    ObjectInputStream objectIn;  // for retrieving new color array (down s socket)
    ObjectOutputStream out;
    PrintWriter outPW;
    //String Player1;
    //String Player2;
    String playerIP;
    String opponentIP;
    int port = 50000;

    TestT(Socket s, int gameNo){
        this.s = s;
        this.gameNo = gameNo;
    }
    public void run(){

        try{
            outPW = new PrintWriter(s.getOutputStream(), true);
            out = new ObjectOutputStream(s.getOutputStream());
            out.writeObject(list);
            in = new Scanner(s.getInputStream());
            outPW.println("returnIP");                            ///get the IP of the client
            clientIPArray.add(in.nextLine());                     /// add it to the clientIPArray
        }
        catch(IOException e){
            e.getStackTrace();  
        }
        JOptionPane.showMessageDialog(new JFrame(), s.getInetAddress().toString() +" has connected.");              
        list[gameNo] = "Game "+Integer.toString(gameNo);
        gamesList.updateUI();   

        }
    }

}

    private void setupConnection(String serverIP, String port){
    int portInt = Integer.parseInt(port);
    serverIp = serverIP;
    try{
        IP = InetAddress.getByName(serverIP);
        clientSocket = new Socket(IP,portInt);
        JOptionPane.showMessageDialog(new JFrame(), "Successfully connected to Server");
        in = new ObjectInputStream(clientSocket.getInputStream());
        out = new PrintWriter(clientSocket.getOutputStream(), true);
        scanIn = new Scanner(clientSocket.getInputStream());
        a = (String[]) in.readObject();
        if(scanIn.nextLine().equals("returnIP"))out.println(clientIp);
        getGamesList(a);
        Thread tss = new Thread(new ClientThread());
        tss.start();
        System.out.println("w");
    }
    catch(Exception e){
        System.out.println("ErrorC :" +e.getMessage());
    }
}

score 0 · Accepted Answer · answered Nov 28 '13 at 18:19

0

Suggestions:

Keep couple of buffers on the server side, refresh them on clients' input and send data when another client is connected
Let server to wait until two clients will be connected and then redirect InputStream of each Socket to OutputStream of another.
Let server to wait until two clients will be connected and then transmit to both clients address of another, let them to communicate p2p (without server)
Any combination of the above

The best way depends on your goals.

answered Nov 28 '13 at 18:19

Sergey Fedorov

2,169
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Talking about suggestions, I'd use [Thrift](http://thrift.apache.org/) or other mature framework to do the dirty work for you. – Gilberto Torrezan Nov 28 '13 at 19:14
Thanks for sharing an useful link! I don't think it is easier than writing on java, but I will keep in mind) – Sergey Fedorov Nov 29 '13 at 15:14
thanks for the suggestions, now i'm trying to recieve an array is this legitimate ? else if(Color[])objectIn.readObject() instanceof Color[]){ //do something} – John Collins Nov 29 '13 at 15:51
`(Color[])` will throw ClassCastException if it is not Color[]. Better split to Object o=objectIn.readObject();if(o instanceof ...) Does it really relate to question? – Sergey Fedorov Nov 29 '13 at 15:57
but then it will be an object not a color[], it seems the above if statement oes not work.. i'd better ask another question – John Collins Nov 29 '13 at 16:10

Connecting two clients via server java

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