使用LinkedHashMap来实现LRU算法

LRU算法：即淘汰最近最少未使用的请求算法

LinkedHashMap中除了具有链表和HashMap的特征之外，还具有实现LRU算法的一些特性。
从其源码注解中可以得知：
This kind of map is well-suited to building LRU caches. Invoking the {@code put}, {@code putIfAbsent}, {@code get}, {@code getOrDefault}, {@code compute}, {@code computeIfAbsent}, {@code computeIfPresent}, or {@code merge} methods results in an access to the corresponding entry (assuming it exists after the invocation completes).
下面是实现的代码：

import java.util.LinkedHashMap;
import java.util.Map;

/**
 * @author yupeiyang
 *
 * 实现LRU算法
 */
public class LruDemo1<K,V> extends LinkedHashMap<K,V> {
    private int capacity; //缓存空间

    public LruDemo1(int capacity){
        //accessOrder : true表示访问顺序、false表示插入顺序
        super(capacity,0.75f,true);
        //super(capacity,0.75f,false);
        this.capacity = capacity;
    }

    @Override
    protected boolean removeEldestEntry(Map.Entry<K, V> eldest) {
        return super.size() > capacity;
    }

    public static void main(String[] args) {
        LruDemo1 lruDemo1 = new LruDemo1(3);

        lruDemo1.put(4,"e");
        lruDemo1.put(3,"c");
        lruDemo1.put(1,"a");
        lruDemo1.put(5,"f");
        lruDemo1.put(2,"b");

        System.out.println(lruDemo1.keySet());
        System.out.println(lruDemo1.values());

        lruDemo1.put(6,"g");

        System.out.println(lruDemo1.keySet());
        System.out.println(lruDemo1.values());
    }
}

执行结果：

本文地址：https://blog.csdn.net/weixin_43157935/article/details/112003697