Cache<String, Integer> cache = Caffeine.newBuilder()
                // 寫(xiě)入緩存后30分鐘后過(guò)期
                .expireAfterWrite(30, TimeUnit.MINUTES)
                // 最大緩存數(shù)量1000
                .maximumSize(1000)
                .build();
        String key = "1";
        // 新增緩存
        cache.put(key, 1);
        cache.put("2", 2);
        cache.put("3", 3);
        // 從緩存中獲取數(shù)據(jù): 如果存在在返回"1"的值，如果不存在返回null
        System.out.println(cache.getIfPresent(key));
        // 緩存key不存在cache中, 則新增一條數(shù)據(jù)到cache中
        String key1 = "4";
        cache.get(key1, k -> 3);
        System.out.println(cache.getIfPresent(key1));
        // 從cache中移除緩存
        cache.invalidate("1");

public void loadingCache() {
    LoadingCache<String, Integer> loadingCache = Caffeine.newBuilder()
            // 寫(xiě)入緩存后30分鐘后過(guò)期
            .expireAfterWrite(30, TimeUnit.MINUTES)
            // 最大緩存數(shù)量1000
            .maximumSize(1000)
            // build中的CacheLoader可以在初始化LoaddingCache時(shí)，加載一部分?jǐn)?shù)據(jù)到內(nèi)存中,
            // 此處就把key的hash值作為value
            .build(this::getIntByKey);
    Integer val = loadingCache.get("1", this::getIntByKey);
    System.out.println(val);
	 // 批量獲取鍵值
    Map<String, Integer> all = loadingCache.getAll(Arrays.asList("1", "2"));
    System.out.println(JSON.toJSONString(all.values()));
}
public Integer getIntByKey(String key) {
    return key.hashCode();
}

public void sync() {
        AsyncCache<String, Integer> asyncCache = Caffeine.newBuilder()
        // 寫(xiě)入緩存后30分鐘后過(guò)期
                .expireAfterWrite(30, TimeUnit.MINUTES)
                // 最大緩存數(shù)量1000
                .maximumSize(1000)
            .buildAsync();
        // 如果Key不存在, 則把key和value 加入到cache中, CompletableFuture提供了一個(gè)阻塞Cache, 直到異步完成
        CompletableFuture<Integer> future = asyncCache.get("1", this::getIntByKey);
    }
    public Integer getIntByKey(String key) {
        return key.hashCode();
    }

 public void syncLoadingCache() {
        AsyncLoadingCache<String, Integer> async = Caffeine.newBuilder().buildAsync(new AsyncCacheLoader<>() {
            @Override
            public @NonNull CompletableFuture<Integer> asyncLoad(@NonNull String key, @NonNull Executor executor) {
                return new CompletableFuture<>();
            }
        });
        CompletableFuture<Integer> future = async.get("1");
        CompletableFuture<Map<String, Integer>> all = async.getAll(Arrays.asList("1", "2"));
    }

Cache<String, Integer> graphs = Caffeine.newBuilder()
                // 設(shè)置一個(gè)定時(shí)器任務(wù)
                .scheduler(Scheduler.systemScheduler())
                // 添加一個(gè)移除元素監(jiān)聽(tīng)事件
                .removalListener((k , v, cause) -> {
                    System.out.println(k);
                    System.out.println(v);
                    System.out.println(cause.wasEvicted());
                })
                .expireAfterWrite(3, TimeUnit.SECONDS)
                .weakValues()
                .build();
        // 創(chuàng)建一個(gè)清理線程
        Cleaner cleaner = Cleaner.create();
        // 注冊(cè)一個(gè)對(duì)象，并在對(duì)象運(yùn)行時(shí)執(zhí)行一個(gè)cleanUp操作
        cleaner.register("1", graphs::cleanUp);
        graphs.put("1", 1);
        graphs.put("2", 2);
        graphs.put("3", 3);
        Thread.sleep(5000);
        graphs.put("3", 3);
        System.out.println(graphs.getIfPresent("1"));
        System.out.println(graphs.getIfPresent("2"));
        System.out.println(graphs.getIfPresent("3"));