LRUCache

import java.util.LinkedHashMap;
import java.util.concurrent.locks.Lock;
import java.util.concurrent.locks.ReentrantLock;

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

	private static final long serialVersionUID = -656812640814484468L;

	/** 默认最大容量 */
	private static final int DEFAULT_MAX_CAPACITY = 300;

	private static final int INITIALCAPACITY = 16;

	/** 负载因子 */
	private static final float DEFAULT_LOAD_FACTOR = 0.75f;

	private final Lock lock = new ReentrantLock();

	private volatile int maxCapacity;

	/**
	 * <br>
	 * ------------------------------<br>
	 */
	public LRUCache() {
		this(DEFAULT_MAX_CAPACITY);
	}

	public LRUCache(int maxCapacity) {
		super(INITIALCAPACITY, DEFAULT_LOAD_FACTOR, Boolean.TRUE);
		this.maxCapacity = maxCapacity;
	}

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

	@Override
	public V get(Object key) {
		try {
			lock.lock();
			return super.get(key);
		} finally {
			lock.unlock();
		}
	}

	public V put(K key, V value) {
		try {
			lock.lock();
			return super.put(key, value);
		} finally {
			lock.unlock();
		}
	}

	@Override
	public V remove(Object key) {
		try {
			lock.lock();
			return super.remove(key);
		} finally {
			lock.unlock();
		}
	}

	@Override
	public boolean containsKey(Object key) {
		try {
			lock.lock();
			return super.containsKey(key);
		} finally {
			lock.unlock();
		}
	}

	@Override
	public void clear() {
		try {
			lock.lock();
			super.clear();
		} finally {
			lock.unlock();
		}
	}

	@Override
	public int size() {
		try {
			lock.lock();
			return super.size();
		} finally {
			lock.unlock();
		}
	}

	/**
	 * 获得maxCapacity
	 * @return the maxCapacity
	 */
	public int getMaxCapacity() {
		return maxCapacity;
	}

	/**
	 * 设置maxCapacity
	 * @param maxCapacity the maxCapacity to set
	 */
	public void setMaxCapacity(int maxCapacity) {
		this.maxCapacity = maxCapacity;
	}
}

public class Main {
	
	public static void main(String[] args) {
		LRUCache<String, String> lruCache = new LRUCache<String, String>(2);
		lruCache.put("1", "1");
		lruCache.put("2", "2");
		System.out.println(lruCache);
		lruCache.put("3", "3");
		System.out.println(lruCache);
	}
}

{1=1, 2=2}
{2=2, 3=3}