import java.util.HashMap;
import java.util.Map;
public class Cache<K, V> {
    // 使用 HashMap 作为底层存储容器
    private Map<K, V> storage = new HashMap<>();
    public void put(K key, V value) {
        storage.put(key, value);
    }
    public V get(K key) {
        return storage.get(key);
    }
    public void remove(K key) {
        storage.remove(key);
    }
    public boolean containsKey(K key) {
        return storage.containsKey(key);
    }
    public int size() {
        return storage.size();
    }
    public static void main(String[] args) {
        Cache<String, String> userCache = new Cache<>();
        userCache.put("user:1001", "Alice");
        userCache.put("user:1002", "Bob");
        String user1 = userCache.get("user:1001");
        System.out.println("获取到的用户: " + user1);
        if (userCache.containsKey("user:1002")) {
            System.out.println("用户 1002 在缓存中");
        }
    }
}