An implementation of the Spring Cache interface on top of Google Guava cache

SpringGuavaCache.java

import java.util.List;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.cache.Cache;
import org.springframework.cache.support.SimpleValueWrapper;

import com.google.common.base.Optional;
import com.google.common.cache.CacheBuilder;
import com.google.common.cache.CacheBuilderSpec;
import com.google.common.collect.ImmutableList;

public class GuavaCache implements Cache {

    private final Logger logger = LoggerFactory.getLogger(this.getClass());

    private final com.google.common.cache.Cache<String, Optional<Object>> cache;

    private final String name;

    public GuavaCache(final String name,
            final com.google.common.cache.Cache<String, Optional<Object>> cache) {
        this.name = name;
        this.cache = cache;
    }

    public GuavaCache(final String name, final CacheBuilderSpec cacheBuilderSpec) {
        this(name, CacheBuilder.from(cacheBuilderSpec).<String, Optional<Object>>build());
    }

    @Override
    public String getName() {
        return name;
    }

    @Override
    public Object getNativeCache() {
        return cache;
    }

    @Override
    public ValueWrapper get(final Object key) {
        String fullKey = decorateKey(key);
        Optional<Object> optional = cache.getIfPresent(fullKey);
        if (optional != null) {
            logger.trace("Cache {} hit: {}", name, fullKey);
        } else {
            logger.trace("Cache {} miss: {}", name, fullKey);
        }
        return optional == null ? null : new SimpleValueWrapper(optional.orNull());
    }

    @Override
    public void put(final Object key, final Object value) {
        String fullKey = decorateKey(key);
        logger.trace("Cache {} put: {}", name, fullKey);
        cache.put(fullKey, Optional.fromNullable(value));
    }

    @Override
    public void evict(final Object key) {
        String fullKey = decorateKey(key);
        logger.trace("Cache {} evict: {}", name, fullKey);
        cache.invalidate(fullKey);
    }

    @Override
    public void clear() {
        logger.trace("Cache {} clear", name);
        cache.invalidateAll();
    }

    public void cleanUp () {
        logger.trace("Cache {} cleanup", name);
        cache.cleanUp();
    }

    public List<Object> values() {
        return ImmutableList.copyOf(Optional.presentInstances(cache.asMap().values()));
    }

    // Override this method in subclasses to add custom behaviour to the cache keys
    protected String decorateKey(final Object key) {
        return key.toString();
    }

}