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AJAXJS aims to full-stack, not only the server-side framework, but also integrates the front-end library. It's written in HTML5 + Java, a successor to the JVM platform, efficient, secure, stable, cross-platform and many other advantages, but it abandoned the traditional enterprise architecture brought about by the large and bloated, emphasizing the lightweight, and fast, very suitable for the Internet fast application.

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package com.ajaxjs.util;

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

/**
 * 带锁的线程安全的LRULinkedHashMap简单实现
 * 
 * @author https://blog.csdn.net/a921122/article/details/51992713
 *
 * @param 
 * @param 
 */
public class LRUCache extends LinkedHashMap {
	private static final long serialVersionUID = -952299094512767664L;

	private final int maxCapacity;

	private static final float DEFAULT_LOAD_FACTOR = 0.75f;

	private final Lock lock = new ReentrantLock();

	public LRUCache(int maxCapacity) {
		super(maxCapacity, DEFAULT_LOAD_FACTOR, true);
		this.maxCapacity = maxCapacity;
	}

	@Override
	protected boolean removeEldestEntry(Map.Entry eldest) {
		return size() > maxCapacity;
	}

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

	/**
	 * 可以根据实际情况，考虑对不同的操作加锁
	 */
	@Override
	public V put(K key, V value) {
		try {
			lock.lock();
			return super.put(key, value);
		} finally {
			lock.unlock();
		}
	}

}