중재자 패턴

// Mediator 인터페이스 interface Mediator { void sendMessage(String message, User user); void addUser(User user); } // ConcreteMediator (구체적인 중재자) class ChatRoom implements Mediator { private List<User> users; public ChatRoom() { this.users = new ArrayList<>(); } @Override public void sendMessage(String message, User user) { for (User u : users) { // 자신에게는 메시지를 보내지 않음 if (u != user) { u.receive(message); } } } @Override public void addUser(User user) { this.users.add(user); } } // Colleague (동료 객체) abstract class User { protected Mediator mediator; protected String name; public User(Mediator mediator, String name) { this.mediator = mediator; this.name = name; } public abstract void send(String message); public abstract void receive(String message); } // ConcreteColleague (구체적인 동료 객체) class ConcreteUser extends User { public ConcreteUser(Mediator mediator, String name) { super(mediator, name); } @Override public void send(String message) { System.out.println(this.name + " sending: " + message); mediator.sendMessage(message, this); } @Override public void receive(String message) { System.out.println(this.name + " received: " + message); } } // Main 클래스에서 사용 예시 public class MediatorPatternExample { public static void main(String[] args) { Mediator chatRoom = new ChatRoom(); User user1 = new ConcreteUser(chatRoom, "Alice"); User user2 = new ConcreteUser(chatRoom, "Bob"); User user3 = new ConcreteUser(chatRoom, "Charlie"); chatRoom.addUser(user1); chatRoom.addUser(user2); chatRoom.addUser(user3); user1.send("Hello, everyone!"); user2.send("Hi Alice, how are you?"); } }

Alice sending: Hello, everyone! Bob received: Hello, everyone! Charlie received: Hello, everyone! Bob sending: Hi Alice, how are you? Alice received: Hi Alice, how are you? Charlie received: Hi Alice, how are you?