Java - Trenes(Cliente/servidor)

package lwp;

import java.io.IOException;

import java.io.ObjectInputStream;

import java.io.ObjectOutputStream;

import java.net.ServerSocket;

import java.net.Socket;

import java.util.ArrayList;

import java.util.BitSet;

public class TrainServer {

	private final Train t;

	private final ServerSocket	ss;

	public enum Result {OK, CANCEL, FULL, BAD};

	/* */

	private TrainServer(Train t) throws IOException {

		this.t = t;

		ss = new ServerSocket(8181);

	}

	/* */

	private void start() throws IOException {

		System.out.println("Server accepting requests on port 8181");

		while(true) {

			try(Socket cs = ss.accept()) {

				final ObjectOutputStream os = new ObjectOutputStream(cs.getOutputStream());

				final ObjectInputStream is = new ObjectInputStream(cs.getInputStream());

				new Thread() {

					@Override

					public void run() {

						while(true) {

							try {

								Reservation rs = (Reservation)is.readObject();

								System.out.printf("%d, %d\n", rs.wagon, rs.seat);

								ReservationResult status = t.takeSeat(rs);

								os.writeObject(status);

								t.showFullStatus();

							} catch(IOException | ClassNotFoundException ex) {

								System.err.println("Can't read petition. Reason: " + ex.getMessage());

								ex.printStackTrace();

								//break;

							}

						}

					}

				}.start();

			} catch(IOException x) {

				System.err.println("Can't accept connection. Reason: " + x.getMessage());

			}

		}

	}

	/* */

	public static void main(String args[]) throws IOException {

		Train t = new Train();

		TrainServer	ts = new TrainServer(t);

		try {

			/* 2 asientos a la izda y 2 a la dcha del pasillo, pasar un múltiplo de 4 */

			t.add(new Wagon(16));

			t.add(new Wagon(32));

		} catch(BadSeatException ex) {

			System.err.println("Error in creation");

			System.exit(1);

		}

		ts.start();

	}

	/* */

	static class Train {

		ArrayList<Wagon> convoy;

		private boolean isFull;

		/* */

		protected Train() {

			convoy = new ArrayList();

			isFull = true;

		}

		/* */

		protected void add(Wagon w) {

			convoy.add(w);

			isFull = false;

		}

		/* */

		protected synchronized ReservationResult takeSeat(Reservation rs) {

			if(isFull) {

				return new ReservationResult(rs, Result.FULL);

			}

			try {

				boolean ok = take(rs.wagon, rs.seat);

				if(ok) {

					for(Wagon w : convoy) {

						isFull = w.isFull ^ isFull;

					}

					return new ReservationResult(rs, Result.OK);

				}

				return new ReservationResult(rs, Result.CANCEL);

			} catch(IndexOutOfBoundsException | BadSeatException ex) {

				System.err.printf("Bad petition (Wagon %d, Seat %d)\n", rs.wagon, rs.seat);

				return new ReservationResult(rs, Result.BAD);

			}

		}

		/* */

		private boolean take(int wagon, int seat) throws BadSeatException {

			try {

				Wagon w = convoy.get(wagon -1);

				return w.takeSeat(seat);

			} catch(IndexOutOfBoundsException x) {

				throw new BadSeatException();

			}

		}

		/* */

		protected void showFullStatus() {

			System.out.println("After last petition: ");

			for(int i = 0; i < 4; i++) {

				for(Wagon w : convoy) {

					System.out.printf("%s ", w.rowString(i));

				}

				System.out.println();

			}

		}

	}

	/* */

	static class Wagon {

		private final int capacity;

		private final BitSet	seats;

		private boolean isFull;

		/* */

		protected Wagon(int cap) throws BadSeatException {

			if((cap <= 0) || (cap > 64)) {

				throw new BadSeatException();

			}

			this.capacity = cap;

			seats = new BitSet(cap);

			isFull = false;

		}

		/* */

		protected boolean takeSeat(int seat) throws BadSeatException {

			if((seat < 0) || (seat > capacity)) {

				throw new BadSeatException();

			}

			if(isFull) {

				return false;

			}

			return take(seat - 1);

		}

		/* */

		private boolean take(int seat) {

			if(seats.get(seat)) {

				return false;

			}

			seats.set(seat);

			isFull = seats.nextClearBit(0) >= capacity;

			return true;

		}

		/* 0 ventanilla dcha, 1 pasillo dcha, 2 pasillo izda, 3 ventanilla izda (por ejemplo) */

		private String rowString(int r) {

			StringBuilder sb = new StringBuilder();

			for(int i = r; i < capacity; i += 3) {

				sb.append((seats.get(i)) ? "*" : "_");

			}

			return sb.toString();

		}

	}

	/* */

	public static class Reservation {

		public int	wagon, seat;

		/* */

		Reservation(int w, int s) {

			wagon = w;

			seat = s;

		}

	}

	/* */

	public static class ReservationResult extends Reservation {

		Result	result;

		/* */

		ReservationResult(Reservation rs, Result status) {

			super(rs.wagon, rs.seat);

			result = status;

		}

	}

	/* */

	private static class BadSeatException extends Exception {

		public BadSeatException() {

			super();

		}

	}

}