面试官：如何设计和实现一个带过期时间的本地缓存？

public interface LocalCache<V> {
    /**
     * 插入数据，数据永久有效
     */
    boolean put(String key, V value);

    /**
     * 插入数据，在指定时间内生效
     */
    boolean put(String key, V value, int seconds);

    /**
     * 是否包含指定的key
     */
    boolean containKey(String key);

    /**
     * 获取指定Key的值
     */
    V get(String key);

    /**
     * 从缓存中移除key对应的数据
     */
    void remove(String key);

    void shutdownNow();
}

public class DefaultLocalCache<V> implements LocalCache<V> {
    // 默认容量
    private static final int DEFAULT_CAPACITY = 1024;
    private static final int MAX_CAPACITY = 100000;

    private static final int DEFAULT_THREAD_SIZE = 1;

    private final int maxSize;

    //数据map
    private volatile ConcurrentHashMap<String,V> dataMap;
    //过期时间
    private final ConcurrentHashMap<String,Long> timeOutMap;

    //定时任务
    private final ScheduledExecutorService executorService;

    public DefaultLocalCache() {
        maxSize = MAX_CAPACITY;
        dataMap = new ConcurrentHashMap<>(DEFAULT_CAPACITY);
        timeOutMap = new ConcurrentHashMap<>(DEFAULT_CAPACITY);
        executorService = new ScheduledThreadPoolExecutor(DEFAULT_THREAD_SIZE) ;
    }

    public DefaultLocalCache(int size) {
        maxSize = size;
        dataMap = new ConcurrentHashMap<>(DEFAULT_CAPACITY);
        timeOutMap = new ConcurrentHashMap<>(DEFAULT_CAPACITY);
        executorService = new ScheduledThreadPoolExecutor(DEFAULT_THREAD_SIZE) ;
    }

    @Override
    public boolean put(String key, V value) {
        //检查容量
        if(checkCapacity()){
            dataMap.put(key,value);
            return true;
        }
        return false;
    }



    @Override
    public boolean put(String key, V value, int seconds) {
        if(checkCapacity()){
            dataMap.put(key,value);
            if(seconds >= 0){
                timeOutMap.put(key,getTimeOut(seconds));
                ClearTask task = new ClearTask(key);
                executorService.schedule(task, seconds, TimeUnit.SECONDS);
            }
        }
        return false;
    }

 ......

    class ClearTask implements Runnable{
        private String key;

        public ClearTask(String key){
            this.key = key;
        }
        @Override
        public void run() {
            //判断缓存中是否有key
            if(timeOutMap.contains(key)){
                //获取失效时间
                Long expire = timeOutMap.get(key);
                //如果失效时间大于0，并且比当前时间小，则删除缓存
                if(expire > 0){
                    long now = System.currentTimeMillis();
                    if(now >= expire){
                        remove(key);
                    }
                }
            }
        }
    }
}