hibernate4如何集成ocs的spymemcached？

Caused by: java.lang.ClassNotFoundException: Could not load requested class : com.googlecode.hibernate.memcached.MemcachedRegionFactory

-------------------------

<!-- hibernate cache config -->
                <!-- 开启二级缓存 -->
                <prop key="hibernate.cache.use_second_level_cache">true</prop>
                <!-- 是否缓存查询结果 -->
                <prop key="hibernate.cache.use_query_cache">true</prop>
                <!-- 缓存提供商 hibernate3配置 -->
                <!-- <prop key="hibernate.cache.provider_class ">com.googlecode.hibernate.memcached.MemcachedCacheProvider</prop> -->
                <!-- 缓存提供商 hibernate4配置 -->
                <prop key="hibernate.cache.region.factory_class">com.googlecode.hibernate.memcached.MemcachedRegionFactory</prop>
                <!-- 设置二级缓存的前缀名称 -->
                <prop key="hibernate.cache.region_prefix">alltest_memcache</prop>
                <!-- 否使用结构化的方式缓存对象
                <prop key="hibernate.cache.use_structured_entries">true</prop>
                强制Hibernate以更人性化的格式将数据存入二级缓存
                <prop key="hibernate.cache.use_structured_entries">true</prop>
                Hibernate将收集有助于性能调节的统计数据
                <prop key="hibernate.generate_statistics">true</prop> -->
                <!-- 切换使用不同的memcache客户端(SpyMemcacheClientFactory) -->
                <prop key="hibernate.memcached.memcacheClientFactory">com.googlecode.hibernate.memcached.spymemcached.SpyMemcacheClientFactory</prop>
                <prop key="hibernate.memcached.servers">${hibernate.memcached.servers}</prop>
                <prop key="hibernate.memcached.cacheTimeSeconds">${hibernate.memcached.cacheTimeSeconds}