java map缓存

/**

 * 缓存池

 * @author xiaoquan

 * @create 2015年3月13日 上午10:32:13

 * @see

 */

public class CachePool {

    private static CachePool instance;//缓存池唯一实例

    private static Map<String,Object> cacheItems;//缓存Map

    private CachePool(){

        cacheItems = new HashMap<String,Object>();

    }

    /**

     * 得到唯一实例

     * @return

     */

    public synchronized static CachePool getInstance(){

        if(instance == null){

            instance = new CachePool();

        }

        return instance;

    }

    /**

     * 清除所有Item缓存

     */

    public synchronized void clearAllItems(){

        cacheItems.clear();

    }

    /**

     * 获取缓存实体

     * @param name

     * @return

     */

    public synchronized Object getCacheItem(String name){

        if(!cacheItems.containsKey(name)){

            return null;

        }

        CacheItem cacheItem = (CacheItem) cacheItems.get(name);

        if(cacheItem.isExpired()){

            return null;

        }

        return cacheItem.getEntity();

    }

    /**

     * 存放缓存信息

     * @param name

     * @param obj

     * @param expires

     */

    public synchronized void putCacheItem(String name,Object obj,long expires){

        if(!cacheItems.containsKey(name)){

            cacheItems.put(name, new CacheItem(obj, expires));

        }

        CacheItem cacheItem = (CacheItem) cacheItems.get(name);

        cacheItem.setCreateTime(new Date());

        cacheItem.setEntity(obj);

        cacheItem.setExpireTime(expires);

    }

    public synchronized void putCacheItem(String name,Object obj){

        putCacheItem(name,obj,-1);

    }

    /**

     * 移除缓存数据

     * @param name

     */

    public synchronized void removeCacheItem(String name){

        if(!cacheItems.containsKey(name)){

            return;

        }

        cacheItems.remove(name);

    }

    /**

     * 获取缓存数据的数量

     * @return

     */

    public int getSize(){

        return cacheItems.size();

    }

}

public class CacheItem {

    private Date createTime = new Date();//创建缓存的时间

    private long expireTime = 1;//缓存期满的时间

    private Object entity;//缓存的实体

    public CacheItem(Object obj,long expires){

        this.entity = obj;

        this.expireTime = expires;

    }

    public boolean isExpired(){

        return (expireTime != -1 && new Date().getTime()-createTime.getTime() > expireTime);

    }

        /**

         * 省略getter、setter方法

         */

}