java - Guava 缓存生成器 : imply additional conditions to entity removal

Question

我想要:当两个条件都成立时删除实体

• 超时已过
• 某些外部条件成立

问题: 除了超时之外，我应该如何暗示其他删除条件？或者如何从删除监听器恢复实体(参见下面的代码)？

我的代码(已仅根据超时删除):

LoadingCache<String, Integer> ints = CacheBuilder.newBuilder()
        .maximumSize(10000)
        .expireAfterAccess(ACCESS_TIMEOUT, TimeUnit.MILLISECONDS)
        .removalListener(
                new RemovalListener() {                       
                    public void onRemoval(RemovalNotification notification) {
                        if (notification.getCause() == RemovalCause.EXPIRED) {
                            if (!isExternalCondition()) {
                               //IS IT POSSIBLE TO RESTORE?
                              restore(notification.getValue()); 
                            }
                        } else {
                            System.out.println("Just removed for some reason");
                        }
                    }
                }
        )
        .build(
                new CacheLoader<String, Integer>() {
                    public Integer load(String key) throws Exception {
                        return new Integer(-1);
                    }
                });

Answer 1

尝试使用 isExternalCondition() 方法的静态类。