public interface cacheable extends Serializable {
    public int getCachedSize();
}

    public synchronized Object put(Object key, Object value)
    {
        remove(key);
        int objectSize = calculateSize(value);
        if(maxCacheSize > 0 && (double)objectSize > (double)maxCacheSize * 0.9)
        {
            Log.warn("Cache: " + name + " -- object with key " + key + " is too large to fit in cache. Size is " + 

objectSize);
            return value;
        } else
        {
            cacheSize += objectSize;
            cacheObject cacheObject = new cacheObject(value, objectSize);
            map.put(key, cacheObject);
            LinkedListNode lastAccessedNode = lastAccessedList.addFirst(key);
            cacheObject.lastAccessedListNode = lastAccessedNode;
            LinkedListNode ageNode = ageList.addFirst(key);
            ageNode.timestamp = System.currentTimeMillis();
            cacheObject.ageListNode = ageNode;
            cullCache();
            return value;
        }
    }

    protected int calculateSize(Object object)
    {
        if(object instanceof cacheable)
            return ((Cacheable)object).getCachedSize();
	......
    }

    public synchronized void put(Object key, Object value) {
        if (key == null)
            return;

        if (maxSize > 0) {
            // when maxSize is changed, the setter will take care of filling the LRU list
            if (cacheLineTable.containsKey(key)) {
                keyLRUList.remove(key);
                keyLRUList.addFirst(key);
            } else {
                keyLRUList.addFirst(key);
            }
        }

        if (expireTime > 0) {
            cacheLineTable.put(key, new UtilCache.CacheLine(value, useSoftReference, System.currentTimeMillis()));
        } else {
            cacheLineTable.put(key, new UtilCache.CacheLine(value, useSoftReference));
        }
        if (maxSize > 0 && cacheLineTable.size() > maxSize) {
            Object lastKey = keyLRUList.getLast();
            remove(lastKey);
        }
    }

    public Object get(Object key) {

        UtilCache.CacheLine line = (UtilCache.CacheLine) cacheLineTable.get(key);

        if (hasExpired(line)) {//如果过期
            remove(key);
            line = null;
        }

        if (line == null) {
            // remove掉后还要告诉我过期！！
            missCount++;
            return null;
        }
    }