自己实现的一个很简单的对象缓存器。顺便请教大家一些比较优秀的缓存器实现思路。

前段时间写的ConnectionPool已经可用运行了，现在转向CachePool，偶还是菜鸟所以只是利用了j2se的api简单的实现了一个对象缓存器，顺便希望大家能够说说缓存器的设计思路（暂时不考虑分布式应用）。谢谢大家了！

这是缓存器核心类。

package cc.vicp.eden.cache;

import java.util.*;

public class CachePool {
	private HashMap<Object, Object> pool;
	private LinkedList list;
	private int capacity;
	
	public CachePool(int size) {
		pool = new HashMap<Object, Object>();
		list = new LinkedList<Object>();
		this.capacity = size;
	}
	
	public synchronized Object get(Object key) {
		Object value = pool.get(key);
		if(value != null) {
			list.remove(key);
			list.addFirst(key);
		}
		return value;
	}
	
	public synchronized void put(Object key, Object value) {
		Object obj = null;
		if(pool.size() >= capacity) {
			obj = list.removeLast();
			pool.remove(obj);
		}
		obj = pool.get(key);
		if(! value.equals(obj)) {
			pool.remove(key);
		}
		pool.put(key, value);
		list.remove(key);
		list.addFirst(key);
	}
	
	public synchronized Object remove(Object key) {
		Object value = pool.get(key);
		list.remove(key);
		return value;
	}
	
	public synchronized void clear() {
		pool.clear();
		list.clear();
	}
}

这是提供了超时检测的缓存器类。

package cc.vicp.eden.cache;

public class CacheManager extends CachePool {
	
	private static final int CAPACITY;
	
	static {
		CAPACITY = 10;
	}
	
	public CacheManager() {
		super(CacheManager.CAPACITY);
	}
	
	@Override
	public synchronized Object get(Object key) {
		Object value = super.get(key);
		if(value instanceof Expireable) {
			Expireable e = (Expireable) value;
			if(e.expire()) {
				remove(key);
				value = null;
			}
		}
		return value;
	}
}

interface Expireable {
	boolean expire();
}

看了之后有点收获啊。以前去看了一下ehcache的文档，看不懂。看了楼主的“超简易”实现稍微懂了一点基本的思想。就是最长时间没有用的最有可能被移出。

你用apache的LRUMap不都解决了吗

其实继承HashMap来做Cache也很简单：）

import java.util.LinkedHashMap;
import java.util.Map;
/**
 * 一个实现LRU算法的Map
 * 
 * @author Arbow
 */
public class LRUMap<K,V> extends LinkedHashMap<K,V>
{
    private static final long serialVersionUID = -4653726313477788815L;

    private final int maxSize;
    
    /**
     * 构造一个指定容量的LRU Map
     * @param maxCapacity 最大容量
     */
    public LRUMap(int maxCapacity)
    {
        super(maxCapacity*4/3 + 1, 0.75f, true);
        this.maxSize = maxCapacity;
    }

    protected boolean removeEldestEntry(Map.Entry<K,V> entry)
    {
        return size() > maxSize;
    }
}