为什么我的番石榴缓存不断覆盖项目？

Question

大家好，使用番石榴缓存的每个人都偶然发现了这样的问题。我正在尝试在 CacheValue 缓存番石榴中实现存储，其中有一些字段。我做了一个基于LoadingCache的guava缓存，我不明白为什么我添加size()元素时它总是1？

我的番石榴放法：

private LoadingCache<String, CacheValue> storage;
private static final Logger LOG = Logger.getLogger(GuavaCache.class);

@Override
public void put(String key, Object value) {
    storage.put(key, (CacheValue) value);
    storage = CacheBuilder.newBuilder()
            .expireAfterAccess(5, TimeUnit.SECONDS)
            .maximumSize(MAX_SIZE)
            .removalListener(notification -> LOG.info("Element was remove: " + notification.getKey()))
            .build(new CacheLoader<String, CacheValue>() {
                @Override
                public CacheValue load(String key) {
                    return (CacheValue) value;
                }
            });
}

我的主要class:

   AbstractCustomCache gg = new GuavaCache();


    for (int i = 0; i < 102; i++) {
        gg.put("ab" + i, new CacheValue("ab" + i, System.currentTimeMillis(), 0));
    }

    gg.get("ab4");
    gg.get("ab2");
    gg.get("ab0");

我的输出：

CacheValue{value=ab0, creationDate=1549027075333, frequency=0}  Size=  1
CacheValue{value=ab1, creationDate=1549027075333, frequency=0}  Size=  1
CacheValue{value=ab2, creationDate=1549027075333, frequency=0}  Size=  1
CacheValue{value=ab3, creationDate=1549027075334, frequency=0}  Size=  1
CacheValue{value=ab4, creationDate=1549027075334, frequency=0}  Size=  1
CacheValue{value=ab5, creationDate=1549027075334, frequency=0}  Size=  1
CacheValue{value=ab6, creationDate=1549027075334, frequency=0}  Size=  1
CacheValue{value=ab7, creationDate=1549027075334, frequency=0}  Size=  1
CacheValue{value=ab8, creationDate=1549027075334, frequency=0}  Size=  1
CacheValue{value=ab9, creationDate=1549027075334, frequency=0}  Size=  1

抽象自定义缓存：

public abstract class AbstractCustomCache implements CustomCache {
    static final int MAX_SIZE = 8;
    private Map<String, CacheValue> storage = new ConcurrentHashMap<>();

    public Map<String, CacheValue> getStorage() {
        return storage;
    }

问题是什么？如何解决？

Answer 1

您每次使用 put 创建 storage = CacheBuilder.newBuilder() request.You 应该创建一次。

storage = CacheBuilder.newBuilder()
            .expireAfterAccess(5, TimeUnit.SECONDS)
            .maximumSize(MAX_SIZE)
            .removalListener(notification -> LOG.info("Element was remove: " + notification.getKey()))
            .build(new CacheLoader<String, CacheValue>() {
                @Override
                public CacheValue load(String key) {
                    return (CacheValue) value;
                }
            });

上面应该在初始化缓存时调用一次。所以实际发生的是，对于每个放置请求，您都会创建新存储并在任何时候将 'cacheValue' 添加到 it.Therefore 最大条目为 1.

为什么我的番石榴缓存不断覆盖项目？

Why does my guava cache constantly overwrite items?

java

caching

guava