基于LinkedHashMap实现LRU

基于LinkedHashMap实现Lru

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

/**
 * 
 * 基于LinkedHashMap实现Lru
 */
public class LruWithLinkedHashMap<K,V> {

    private static final float hashLoadFactory = 0.75f;
    private LinkedHashMap<K,V> map;
    private int cacheSize;

    public LruWithLinkedHashMap(int cacheSize) {
        this.cacheSize = cacheSize;
        int capacity = (int)Math.ceil(cacheSize / hashLoadFactory) + 1;
        map = new LinkedHashMap<K,V>(capacity, hashLoadFactory, true){
            @Override
            protected boolean removeEldestEntry(Map.Entry eldest) {
                return size() > cacheSize;
            }
        };
    }

    public synchronized V get(K key) {
        return map.get(key);
    }

    public synchronized void put(K key, V value) {
        map.put(key, value);
    }

    public synchronized void clear() {
        map.clear();
    }

    public synchronized int usedSize() {
        return map.size();
    }

    public void print() {
        for (Map.Entry<K, V> entry : map.entrySet()) {
            System.out.print(entry.getValue() + "--");
        }
        System.out.println();
    }

    public static void main(String[] args) throws Exception {
        LruWithLinkedHashMap<String,String> lru=new LruWithLinkedHashMap(20);
        lru.put("1","1");
        lru.put("2","2");
        lru.put("3","3");
        lru.print();
        System.out.println(lru.usedSize());
    }
}