如何获取Spring-cache中缓存的大小？

<bean id="cacheManager" class="org.springframework.cache.concurrent.ConcurrentMapCacheManager">
    <property name="cacheNames">
        <set>
            <value>cacheName1</value>
            <value>cacheName2</value>
            <!-- 添加其他缓存名称 -->
        </set>
    </property>
</bean>

@Autowired
private CacheManager cacheManager;

public void getCacheSize() {
    for (String cacheName : cacheManager.getCacheNames()) {
        Cache cache = cacheManager.getCache(cacheName);
        if (cache != null) {
            // 获取缓存的大小
            int size = cache.getNativeCache().size();
            System.out.println("Cache " + cacheName + " size: " + size);
        }
    }
}