July 18, 2022
01.옵저버패턴으로 적용
01.1 Subcriber
01.2 User
01.3 ChatServer
01.4 client
public interface Subscriber {
void handleMessage(String message);
}
public class User implements Subscriber {
private String name;
public User(String name) {
this.name = name;
}
public String getName() {
return name;
}
@Override
public void handleMessage(String message) {
System.out.println(message);
}
}
before
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
public class ChatServer {
private Map<String, List<String>> messages;
public ChatServer() {
this.messages = new HashMap<>();
}
public void add(String subject, String message) {
if (messages.containsKey(subject)) {
messages.get(subject).add(message);
} else {
List<String> messageList = new ArrayList<>();
messageList.add(message);
messages.put(subject, messageList);
}
}
public List<String> getMessage(String subject) {
return messages.get(subject);
}
}
after
import java.lang.ref.WeakReference;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
public class ChatServer {
private Map<String, List<Subscriber>> subscribers = new HashMap<>();
public void register(String subject, Subscriber subscriber) {// 등록
if (this.subscribers.containsKey(subject)) {
this.subscribers.get(subject).add(subscriber);
} else {
List<Subscriber> list = new ArrayList<>();
list.add(subscriber);
this.subscribers.put(subject, list);
}
}
public void unregister(String subject, Subscriber subscriber) {// 해지
if (this.subscribers.containsKey(subject)) {
this.subscribers.get(subject).remove(subscriber);
}
}
public void sendMessage(User user, String subject, String message) {//상태변경 기능
if (this.subscribers.containsKey(subject)) {
String userMessage = user.getName() + ": " + message;
this.subscribers.get(subject).forEach(s -> s.handleMessage(userMessage));
}
}
}
public class Client {
public static void main(String[] args) {
ChatServer chatServer = new ChatServer();
User user1 = new User(chatServer);
user1.sendMessage("디자인패턴", "이번엔 옵저버 패턴입니다.");
user1.sendMessage("롤드컵2021", "LCK 화이팅!");
User user2 = new User(chatServer);
System.out.println(user2.getMessage("디자인패턴"));
user1.sendMessage("디자인패턴", "예제 코드 보는 중..");
System.out.println(user2.getMessage("디자인패턴"));
}
}
package me.whiteship.designpatterns._03_behavioral_patterns._19_observer._02_after;
public class Client {
public static void main(String[] args) {
ChatServer chatServer = new ChatServer();
User user1 = new User("keesun");
User user2 = new User("whiteship");
chatServer.register("오징어게임", user1);
chatServer.register("오징어게임", user2);
chatServer.register("디자인패턴", user1);
chatServer.sendMessage(user1, "오징어게임", "아.. 이름이 기억났어.. 일남이야.. 오일남");
chatServer.sendMessage(user2, "디자인패턴", "옵저버 패턴으로 만든 채팅");
chatServer.unregister("디자인패턴", user2);
chatServer.sendMessage(user2, "디자인패턴", "옵저버 패턴 장, 단점 보는 중");
}
}