LRUCache

public class LRUCache<K, V> extends LinkedHashMap<K, V> {

    private static final long serialVersionUID = 3125099067311409227L;

    private Integer cacheSize;

    public LRUCache(Integer cacheSize) {
        super(cacheSize * 3/ 4 + 1, 0.75f, true);
        this.cacheSize = cacheSize;
    }

    @Override
    protected boolean removeEldestEntry(Map.Entry<K, V> eldest) {
        if (size() > cacheSize) {
            return true;
        }
        return false;

        //return super.removeEldestEntry(eldest);
    }


}

public class MyTest {

    public static void main(String[] args) {

        Map<String, String> map = new LRUCache<>(4);
        map.put("1", "1");
        map.put("2", "2");
        map.put("3", "3");
        map.put("4", "4");
        map.put("5", "5");
        map.put("6", "6");
        map.put("1", "1");


        //map.get("3");
        //map.get("6");
        //map.get("1");

        for (Map.Entry entry : map.entrySet()) {
            System.out.println(entry.getKey() + "=========" + entry.getValue());
        }

    }
}

运行结果：

4=========4
5=========5
6=========6
1=========1