chatserver.java

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/**
 * Returns dynamic id of a User currently online or -1 if he is not online.
 *
 * @param userNameParam      the User's name
 */

  public int getOnlineUserId(String userNameParam) {
    Enumeration userEnum;
    User user;

    userEnum = onlineTable.elements();

    while(userEnum.hasMoreElements()) {
      if (((user = (User)userEnum.nextElement())).getName().equals(userNameParam))
        return user.getId();
    }
    return -1;
  }


/**
 * Returns the true if a User's name exists already.
 *
 * @param userNameParam      the User's name
 */

  public boolean exists(String userNameParam) {
    return new File(storageFolder + userNameParam).exists();
  }


/**
 * Stores a User to the ChatServer's local file system. The User's name will be
 * used as the filename.
 *
 * @param userParam      the User to be stored
 */

  public void saveUser(User userParam) {
    save(userParam, storageFolder + userParam.getName());
  }


/**
 * Loads a User from the ChatServer's local file system.
 *
 * @param userNameParam      the name of the User to be loaded
 */

  public User loadUser(String userNameParam) {
    Object loadedObject;
    loadedObject = load(storageFolder + userNameParam);
    if (loadedObject instanceof User)
      return (User)loadedObject;
    else
      return null;
  }


/**
 * Deletes a User from the ChatServer's local file system.
 *
 * @param userNameParam      the name of the User to be loaded
 */

  private synchronized void deleteUser(String userNameParam) {
    new File(storageFolder + userNameParam).delete();
  }


/**
 * Returns the next available User id. The id will be created dynamically.
 */

  public synchronized int getNextAvailableUserId() {
    int id;
    do {
      id = rand.nextInt();
    } while (onlineTable.containsKey(id));
    return id;
  }


/**
 * Returns the next available Room id. The id will be created dynamically.
 */

  public synchronized int getNextAvailableRoomId() {
    return roomTable.getMaxKey() + 1;
  }


/**
 * Returns whether a password is correct or not.
 */

  public boolean correctPassword(String userNameParam, String userPasswordParam) {
    Object loadedObject;
    loadedObject = loadUser(userNameParam);
    if (loadedObject instanceof User)
      return ((User)loadedObject).getPassword().equals(userPasswordParam);
    else
      return false;
  }


/**
 * Stores an object under a given filename to the ChatServer's local file system.
 *
 * @param objectParam      the object to be stored
 * @param fileName         the filename under which to store the object
 */

  public synchronized void save(Object objectParam, String fileName) {
    ObjectOutputStream output;
    try {
      output = new ObjectOutputStream(new FileOutputStream(fileName));
      output.writeObject(objectParam);
      output.close();
    }
    catch (IOException excpt) {
      log("IOException while writing file " + fileName);
    }
  }


/**
 * Loads an object from the ChatServer's local file system.
 *
 * @param fileName      the filename under which the object is stored
 */

  public synchronized Object load(String fileName) {
    ObjectInputStream input;
    Object object;
    object = null;

    try {
      input = new ObjectInputStream(new FileInputStream(fileName));
      object = input.readObject();
      input.close();
    }
    catch (ClassNotFoundException excpt) {
      log("ClassNotFoundException while reading file " + fileName);
    }
    catch (IOException excpt) {
      log("IOException while reading file " + fileName);
    }
    return object;
  }


/**
 * Adds a User to the list of currently logged in users.
 *
 * @param userParam      the User to be added
 */

  public void addOnlineUser(User userParam) {
    onlineTable.put(userParam.getId(), userParam);
  }


/**
 * Removes a User from the list of currently logged in users.
 *
 * @param idParam      the id of the User to be removed
 */

  public void removeOnlineUser(int idParam) {
    onlineTable.remove(idParam);
  }


/**
 * Adds a Room.
 *
 * @param roomParam      the Room to be added
 */

  public void addRoom(Room roomParam) {
    roomTable.put(roomParam.getId(), roomParam);
  }


/**
 * Removes a Room.
 *
 * @param idParam      the id of the Room to be removed
 */

  public void removeRoom(int idParam) {
    roomTable.remove(idParam);
  }


/**
 * Returns a User from the list of currently logged in users.
 *
 * @param idParam      the id of the User to be returned
 */

  public User getOnlineUser(int idParam) {
    Object object;
    object = onlineTable.get(idParam);
    if (object != null)
      return (User)object;
    else
      return null;
  }


/**
 * Returns a Room.
 *
 * @param idParam      the id of the Room to be returned
 */

  public Room getRoom(int idParam) {
    Object object;
    object = roomTable.get(idParam);
    if (object != null)
      return (Room)object;
    else
      return null;
  }


/**
 * Returns a free position in a certain Room to place the User after logging in.
 *
 * @param roomid      the number of the Room to place the User
 */

  public synchronized Point getAvailablePosition(int roomId) {
    Point position, userPosition;
    Enumeration userEnum;

    do {
      position = new Point((int)(rand.nextDouble() * (double)ChatRepository.ROOM_DIMENSION.width - 2.0) + 1, (int)(rand.nextDouble() * (double)ChatRepository.ROOM_DIMENSION.height - 2.0) + 1);
    }
    while (collides(roomId, position, -1));

    return position;
  }


/**
 * Checks whether a Point in a Room collides with a User being placed there.
 *
 * @param roomid             the number of the Room
 * @param position           the position to be checked
 * @param excludeUserId      exclude the position of this User
 */

  public boolean collides(int roomId, Point position, int excludeUserId) {
    Enumeration userEnum;
    User user;
    userEnum = onlineTable.elements();
    while (userEnum.hasMoreElements()) {
      if ((user = (User)userEnum.nextElement()).getRoom() == roomId && user.getId() != excludeUserId) {
        if (new Rectangle(user.getPosition().x - ChatRepository.USER_SIZE / 2 - ChatRepository.MINIMUM_DISTANCE, user.getPosition().y - ChatRepository.USER_SIZE / 2 - ChatRepository.MINIMUM_DISTANCE, ChatRepository.USER_SIZE + ChatRepository.MINIMUM_DISTANCE * 2, ChatRepository.USER_SIZE + ChatRepository.MINIMUM_DISTANCE * 2).contains(position))
          return true;
      }
    }
    return false;
  }

/**
 * Writes a timestamp and logging information to the standard output.
 *
 * @param logText      the text to be logged
 */

  public synchronized void log(String logText) {
    log(logText, STANDARD_LOGLEVEL);
  }


/**
 * Writes a timestamp and logging information to the standard output.
 *
 * @param logText      the text to be logged
 * @param level        the logLevel
 */

  public synchronized void log(String logText, int level) {
    if (level <= logLevel) {
      System.out.println(DateFormat.getDateInstance(DateFormat.SHORT).format(new Date()) + " " + DateFormat.getTimeInstance(DateFormat.MEDIUM).format(new Date()) + ": " + logText);
    }
  }


/**
 * Returns the folder where images should be stored.
 */

  public String getImageFolder() {
    return imageFolder;
  }


/**
 * Returns a Vector which contains the names of all Users that are stored.
 */

  public Vector getUserListVector() {
    String[] userFileList;
    Vector userListVector;

    userListVector = new Vector();

    userFileList = new File(storageFolder).list();
    for (int i = 0; i < userFileList.length; i++)
      userListVector.addElement(userFileList[i]);

    return userListVector;

  }


/**
 * Creates the standard Rooms. Is being called after starting the ChatServer for
 * the first time.
 */

  private void createStandardRooms() {
    Room room;
    roomTable = new IntegerHashtable();
    for (int i = 0; i < ChatRepository.STANDARD_ROOM_NAME.length; i++) {
      room = new Room(i, ChatRepository.STANDARD_ROOM_NAME[i], ChatRepository.ROOM_DIMENSION);
      room.setPrivate(ChatRepository.STANDARD_ROOM_PRIVATE[i]);
      room.setAdministrator(ChatRepository.ADMIN);
      addRoom(room);
    }
    log("Created standard rooms...");
    saveRooms();
  }


/**
 * Persistently stores all the Rooms to the server's file system.
 */

  private void saveRooms() {
    save(roomTable, roomFolder + roomFilename);
    log("Saved rooms...");
  }

}