EchoServerExperiments.java

import rx.Observable;
import rx.schedulers.Schedulers;

import java.io.*;
import java.net.ServerSocket;
import java.net.Socket;
import java.net.UnknownHostException;
import java.util.concurrent.CountDownLatch;

/**
 * Created by lintonye on 15-10-23.
 */
public class EchoServerExperiments {
    public static void main(String[] args) {
        try {
            new EchoServerExperiments().runit();
        } catch (InterruptedException e) {
            e.printStackTrace();
        }
    }

    private void runit() throws InterruptedException {
        CountDownLatch latch = new CountDownLatch(1);

        Observable<String> stdinStream = createStdinStream();

        createServerStream(12345).subscribeOn(Schedulers.io())
                .subscribe(socketStream ->
                        socketStream.subscribeOn(Schedulers.newThread())
                                .subscribe(output -> System.out.println("Server received: " + output)));

        createClientStream("localhost", 12345, stdinStream).subscribeOn(Schedulers.newThread())
                .subscribe(output -> System.out.println("Client received: " + output));

        latch.await();
    }

    private Observable<String> createStdinStream() {
        return Observable.create(sub -> {
            String line;
            BufferedReader reader = new BufferedReader(new InputStreamReader(System.in));
            try {
                while ((line = reader.readLine()) != null) {
                    sub.onNext(line);
                }
            } catch (IOException e) {
                sub.onError(e);
            }
        });
    }

    private Observable<String> createClientStream(String host, int port, Observable<String> inputStream) {
        return Observable.create(sub -> {
            try (Socket socket = new Socket(host, port);
                 BufferedReader inFromServer = new BufferedReader(new InputStreamReader(socket.getInputStream()));
                 DataOutputStream outputStream = new DataOutputStream(socket.getOutputStream());
                 PrintWriter outWriter = new PrintWriter(outputStream, true);
            ) {
                d("Client conntected");
                inputStream.subscribe(line -> {
                    outWriter.println(line);
                    try {
                        sub.onNext(inFromServer.readLine());
                    } catch (IOException e) {
                        sub.onError(e);
                    }
                });
            } catch (UnknownHostException e) {
                sub.onError(e);
            } catch (IOException e) {
                sub.onError(e);
            }
        });
    }

    private Observable<Observable<String>> createServerStream(int port) {
        return Observable.create(sub -> {
            try {
                ServerSocket serverSocket = new ServerSocket(port);
                while (!sub.isUnsubscribed()) {
                    Socket connectionSocket = serverSocket.accept();
                    d("Accepted: remote=%s, local=%s", connectionSocket.getRemoteSocketAddress(), connectionSocket.getLocalAddress());
                    sub.onNext(createServerSocketStream(connectionSocket));
                }
            } catch (IOException e) {
                sub.onError(e);
            }
        });
    }

    private Observable<String> createServerSocketStream(Socket connectionSocket) {
        return Observable.create(sub -> {
            try (
                    Socket socket = connectionSocket;
                    BufferedReader in = new BufferedReader(new InputStreamReader(socket.getInputStream()));
                    DataOutputStream out = new DataOutputStream(socket.getOutputStream());
                    PrintWriter outWriter = new PrintWriter(out, true);
            ) {
                String input;
                while (!sub.isUnsubscribed() && (input = in.readLine()) != null) {
                    sub.onNext(input);
                    outWriter.println(input.toUpperCase());
                }
            } catch (IOException e) {
                sub.onError(e);
            }
        });
    }

    private void d(String format, Object... args) {
        String output = String.format(format, args);
        System.out.println(String.format("Thread:%2d - %s", Thread.currentThread().getId(), output));
    }
}