ExecutorService executorService;

ServerSocket serverSocket;

List<Client> connections = new Vector<Client>(); // 스레드에 안전함

void startServer(){

// 서버 시작 코드 (Executor Service 생성, ServerSocket 생성 및 포트 바인딩, 연결 수락)

executorService = Executors.newFixedThreadPool(Runtime.getRuntime().availableProcessors());

try{

serverSocket = new ServerSocket();

serverSocket.bind(new InetSocketAddress("localhost", 5001));

}catch(Exception e){

if(!serverSocket.isClosed()) { stopServer();}

return;

}

Runnable runnable = new Runnable() { // 수락 작업을 생성

@Override

public void run() {

Platform.runLater(()-> {

// UI 설정

displayText("[서버 시작]");

btnStartStop.setText("stop");

});

while(true){

try{

Socket socket = serverSocket.accept(); // 연결 수락

String message = "[연결 수락 : " + socket.getRemoteSocketAddress() + ": " + Thread.currentThread().getName() + "]";

Platform.runLater(()->displayText(message));

Client client = new Client(socket);

connections.add(client);

Platform.runLater(()-> displayText("[연결 개수 : " + connections.size() + " ]"));

}catch(Exception e){

if(!serverSocket.isClosed()) { stopServer();}

break;

}

}

}

};

executorService.submit(runnable); // 스레드 풀에서 처리

}

void stopServer(){

// 서버 종료 코드

try{

Iterator<Client> iterator = connections.iterator();

while(iterator.hasNext()){ // 모든 socket 닫기

Client client = iterator.next();

client.socket.close();

iterator.remove();

}

if(serverSocket != null && !serverSocket.isClosed()){ // server socket 닫기

serverSocket.close();

}

if(executorService != null && !executorService.isShutdown()){ // ExecutorService 종료

executorService.shutdown();

}

Platform.runLater(() -> {

displayText("[서버 멈춤]");

btnStartStop.setText("start");

});

}catch(Exception e){ }

}

class Client {

// 데이터 통신 코드

Socket socket;

Client(Socket socket){

this.socket = socket;

receive();

}

void receive(){

// 데이터 받기 코드

Runnable runnable = new Runnable() { // 받기 작업 생성

@Override

public void run() {

try{

while(true){

byte[] byteArr = new byte[100];

InputStream inputStream = socket.getInputStream();

int readByteCount = inputStream.read(byteArr); // 데이터 받기

// 클라이언트가 정상적으로 Socket의 close()를 호출했을 경우

if(readByteCount == -1) { throw new IOException();}

String message = "[요청 처리: " + socket.getRemoteSocketAddress() + ": " + Thread.currentThread().getName() + "]";

Platform.runLater(()->displayText(message));

String data = new String(byteArr, 0, readByteCount, "UTF-8");

for(Client client : connections){

client.send(data); // 모든 클라이언트에게 보냄

}

}

}catch(Exception e){

try{

connections.remove(Client.this);

String message = "[클라이언트 통신 안됨: " + socket.getRemoteSocketAddress() + ": " + Thread.currentThread().getName() + " ]";

Platform.runLater(()->displayText(message));

socket.close();

}catch(IOException e2) {}

}

}

};

executorService.submit(runnable); // 스레드풀에서 처리

}

void send(String data){

// 데이터 전송 코드

Runnable runnable = new Runnable() { // 보내기 작업 생성

@Override

public void run() {

try{

byte[] byteArr = data.getBytes("UTF-8");

OutputStream outputStream = socket.getOutputStream();

outputStream.write(byteArr);

outputStream.flush();

}catch(Exception e){

try {

String message = "[클라이언트 통신 안됨: " + socket.getRemoteSocketAddress() + ": " + Thread.currentThread().getName() + " ]";

Platform.runLater(() -> displayText(message));

connections.remove(Client.this);

socket.close();

}catch(IOException e2) {}

}

}

};

executorService.submit(runnable); // 스레드풀에서 처리

}

}

////////

// UI 생성 코드

TextArea txtDisplay;

Button btnStartStop;

@Override

public void start(Stage primaryStage) {

BorderPane root = new BorderPane();

root.setPrefSize(500, 300);

txtDisplay = new TextArea();

txtDisplay.setEditable(false);

BorderPane.setMargin(txtDisplay, new Insets(0,0,2,0));

root.setCenter(txtDisplay);

btnStartStop = new Button("start");

btnStartStop.setPrefHeight(30);

btnStartStop.setMaxWidth(Double.MAX_VALUE);

btnStartStop.setOnAction(e->{

if(btnStartStop.getText().equals("start")){

startServer();

}else if(btnStartStop.getText().equals("stop")){

stopServer();

}

});

root.setBottom(btnStartStop);

Scene scene = new Scene(root);

scene.getStylesheets().add(getClass().getResource("app.css").toString());

primaryStage.setScene(scene);

primaryStage.setTitle("Server");

primaryStage.setOnCloseRequest(event->stopServer());

primaryStage.show();

}

void displayText(String text){

txtDisplay.appendText(text + "\n");

}

public static void main(String[] args){

launch(args);

}

}