无限可观测性到HashMap为可观测性

import java.util.HashMap;
import java.util.Map;

interface Observer {
    void update(Map<String, Object> state);
}

class ObservableHashMap<K, V> extends HashMap<K, V> {
    private List<Observer> observers = new ArrayList<>();

    public void addObserver(Observer observer) {
        observers.add(observer);
    }

    public void removeObserver(Observer observer) {
        observers.remove(observer);
    }

    @Override
    public V put(K key, V value) {
        V oldValue = super.put(key, value);
        notifyObservers();
        return oldValue;
    }

    @Override
    public V remove(Object key) {
        V oldValue = super.remove(key);
        notifyObservers();
        return oldValue;
    }

    private void notifyObservers() {
        for (Observer observer : observers) {
            observer.update(new HashMap<>(this));
        }
    }
}

import java.util.HashMap;
import java.util.Map;

class ObservableHashMapProxy<K, V> implements Map<K, V> {
    private Map<K, V> realMap = new HashMap<>();
    private Observer observer;

    public ObservableHashMapProxy(Observer observer) {
        this.observer = observer;
    }

    @Override
    public V put(K key, V value) {
        V oldValue = realMap.put(key, value);
        observer.update(new HashMap<>(realMap));
        return oldValue;
    }

    @Override
    public V remove(Object key) {
        V oldValue = realMap.remove(key);
        observer.update(new HashMap<>(realMap));
        return oldValue;
    }

    // Implement other Map methods by delegating to realMap
    // ...
}

class MyObserver implements Observer {
    @Override
    public void update(Map<String, Object> state) {
        System.out.println("HashMap state updated: " + state);
    }
}

public class Main {
    public static void main(String[] args) {
        ObservableHashMap<String, String> observableMap = new ObservableHashMap<>();
        observableMap.addObserver(new MyObserver());

        observableMap.put("key1", "value1");
        observableMap.put("key2", "value2");
        observableMap.remove("key1");
    }
}