Guava缓存需要的一些import

import com.google.common.cache.Cache;
import com.google.common.cache.CacheBuilder;
import com.google.common.cache.CacheLoader;
import com.google.common.cache.ForwardingCache;
import com.google.common.cache.ForwardingLoadingCache;
import com.google.common.cache.LoadingCache;
import com.google.common.cache.RemovalListener;
import com.google.common.cache.Weigher;
import com.google.common.cache.CacheLoader.UnsupportedLoadingOperationException;