Java固定内存映射

Question

是否有一个简单、高效的 Map 实现，允许限制 map 使用的内存。

我的用例是我想在创建时动态分配大部分可用内存，但我不想在以后任何时候出现 OutOFMemoryError。基本上，我想将此 map 用作缓存，但我想避免像 EHCache 这样的重型缓存实现。我的需求很简单(顶多一个LRU算法)

我应该进一步澄清，我的缓存中的对象是 char[] 或类似的原语，它们不会保存对其他对象的引用。

我可以为每个条目设置最大大小的上限。

Answer 1

您可以使用 LinkedHashMap 限制 Map 中的条目数:

removeEldestEntry(Map.Entry<K,V> eldest): Returns true if this map should remove its eldest entry. This method is invoked by put and putAll after inserting a new entry into the map. It provides the implementor with the opportunity to remove the eldest entry each time a new one is added. This is useful if the map represents a cache: it allows the map to reduce memory consumption by deleting stale entries.

Sample use: this override will allow the map to grow up to 100 entries and then delete the eldest entry each time a new entry is added, maintaining a steady state of 100 entries.

private static final int MAX_ENTRIES = 100;

protected boolean removeEldestEntry(Map.Entry eldest) {
    return size() > MAX_ENTRIES;
}

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