I am currently programming an online chess game and wanted to host multiple server on 1 PC. It also works when I play with two players, but if I start a third player, it can't connect to server.
The code for the player:
public Socket socket;
public int PlayerID;
public ReadFromServer rfs;
public WriteToServer wts;
public void connectToServer(){
for (int i = 1;i <=3 ;i ) {
try {
socket = new Socket("localhost",(1000 i));
DataInputStream in = new DataInputStream(socket.getInputStream());
DataOutputStream out = new DataOutputStream(socket.getOutputStream());
PlayerID = in.readInt();
System.out.println("You are Player Number:" PlayerID);
if(PlayerID == 1){
System.out.println("Waiting for Oponent...");
}
rfs = new ReadFromServer(in);
wts = new WriteToServer(out);
Thread rT = new Thread(rfs);
Thread wT = new Thread(wts);
rT.start();
wT.start();
i = 4;
} catch(IOException e) {
System.out.println("ERROR at: connect to Server");
}
}
}
public static void main(String[] args) {
PlayerFrame pf = new PlayerFrame();
pf.connectToServer();
pf.GUI();
}
The Server code:
import java.io.*;
import java.net.*;
import java.net.InetAddress;
public class GameServer {
public int GameNumber = 3;
public ServerSocket ss;
public int numPlayers;
public int maxPlayers;
public Socket socket1;
public Socket socket2;
public ReadFromClient p1read;
public ReadFromClient p2read;
public WriteToClient p1write;
public WriteToClient p2write;
public GameServer[] gs;
public int p1x1,p1x2,p1y1,p1y2,p2x1,p2x2,p2y1,p2y2;
public GameServer(){
gs = new GameServer[GameNumber];
Thread[] server = new Thread[GameNumber];
ServerThread[] thread = new ServerThread[GameNumber];
for (int i = 0;i < gs.length ;i ) {
gs[i] = new GameServer((1000 i 1));
thread[i] = new ServerThread(i);
server[i] = new Thread(thread[i]);
server[i].start();
} // end of for
}
public GameServer(int i){
System.out.println("=====Game Server=====");
numPlayers = 0;
maxPlayers = 2;
try {
ss = new ServerSocket(i);
} catch(IOException e) {
System.out.println("ERROR at: Server Construction");
}
}
public void acceptConnections(){
try {
System.out.println("Waiting for connections...");
while (numPlayers < maxPlayers) {
Socket s = ss.accept();
DataInputStream in = new DataInputStream(s.getInputStream());
DataOutputStream out = new DataOutputStream(s.getOutputStream());
numPlayers ;
out.writeInt(numPlayers);
System.out.println("Player Number " numPlayers " has connected");
ReadFromClient rfc = new ReadFromClient(numPlayers,in);
WriteToClient wtc = new WriteToClient(numPlayers,out);
if(numPlayers == 1){
socket1 = s;
p1read = rfc;
p1write = wtc;
Thread read1 = new Thread(p1read);
Thread write1 = new Thread(p1write);
read1.start();
write1.start();
}
else{
socket2 = s;
p2read = rfc;
p2write = wtc;
Thread read2 = new Thread(p2read);
Thread write2 = new Thread(p2write);
read2.start();
write2.start();
}
} // end of while
System.out.println("No longer accepting connections");
} catch(IOException e) {
System.out.println("ERROR at: acceptConnections");
}
}
public static void main(String[] args) {
new GameServer();
}
public class ReadFromClient implements Runnable{
public int playerID;
public DataInputStream dataIn;
public ReadFromClient(int pid, DataInputStream in){
playerID = pid;
dataIn = in;
System.out.println("RFC " playerID " Runnable created");
}
@Override
public void run(){
try {
while (true) {
if(playerID == 1){
p1x1 = dataIn.readInt();
p1y1 = dataIn.readInt();
p1x2 = dataIn.readInt();
p1y2 = dataIn.readInt();
}
else{
p2x1 = dataIn.readInt();
p2y1 = dataIn.readInt();
p2x2 = dataIn.readInt();
p2y2 = dataIn.readInt();
}
try {
Thread.sleep(25);
} catch(InterruptedException ex) {
System.out.println("ERROR at RFS Run");
}
} // end of while
} catch(IOException e) {
System.out.println("ERROR at: RFS");
}
}
}
public class WriteToClient implements Runnable{
public int playerID;
public DataOutputStream dataout;
public WriteToClient(int pid, DataOutputStream out){
playerID = pid;
dataout = out;
System.out.println("WTC " playerID " Runnable created");
}
@Override
public void run(){
try {
while (true) {
if(playerID == 1){
dataout.writeInt(p2x1);
dataout.writeInt(p2y1);
dataout.writeInt(p2x2);
dataout.writeInt(p2y2);
dataout.flush();
}
else{
dataout.writeInt(p1x1);
dataout.writeInt(p1y1);
dataout.writeInt(p1x2);
dataout.writeInt(p1y2);
dataout.flush();
}
try {
Thread.sleep(25);
} catch(InterruptedException ex) {
System.out.println("ERROR at WTC Run");
}
} // end of while
} catch(IOException e) {
System.out.println("ERROR at: WTC run");
}
}
}
public class ServerThread implements Runnable{
public int num;
public ServerThread(int i){
num = i;
}
@Override
public void run(){
gs[num].acceptConnections();
}
}
} // end of class GameServer
I don't get any errors, even though a window doesn't pop up when I run the third player, making.
CodePudding user response：
Have just one ServerSocket and a single loop, and on accepting a client socket start a game running thread using that socket.
ServerSocket serverSocket = ...
ExecutorService executorService = Executors.newFixedThreadPool(4);
while (!executorService .isTerminated()) {
Socket socket = serverSocket.accept();
Runnable gameRun = () -> { ... socket ... };
// like new WorkerThread("...");
executorService .execute(gameRun);
}
executorService .shutdown();
You can do it more neat than here, the thread and passing the socket and such.
The above runs every game conversation in its own thread. It has one main loop on the server socket, which is crucial; you should not use the same ServerSocket in two threads.
You can easily being overrung by a DoS attack (Denial of Service, by hundreds of requests). Just keep an eye on the count of the number of threads.
On request
I cannot code here an entire client-server dialog. For that you should look at examples, that probably are way better than what I can write here. Also my code is not compiled.
Some code snippets. First I would not exchange binary data, but text. That makes developing and especially debugging easier. Also with chess notation everything is almost done.
Runnable gameRun = new GameRun(socket);
executorService .execute(gameRun);
class GameRun implements Runnable, Autoclosable {
final BufferedReader in;
final PrintWriter out
GameRun(Socket socket) {
in = new BufferedReader(
new InputStreamReader(
socket.getInputStream(),
StandardCharsets.UTF_8));
out = new PrintWriter(
new BufferedWriter(
new OutputStreamWriter(
socket.getOutputStream(),
StandardCharsets.UTF_8)));
}
@Override
public void close() {
in.close();
out.close();
}
@Override
public void run() {
for (;;) {
out.println("Your move/action:");
if (!in.ready()) {
out.println("I am awaiting...");
//continue;
}
String line = in.readLine();
out.println("echo " line);
if (line == null) {
break;
}
}
}
}
The client should do something similar.