Lightweight Java Object cache API [closed]

Question

Question

I'm looking for a Java in-memory object caching API. Any recommendations? What solutions have you used in the past?

Current

Right now, I'm just using a Map:

Map cache = new HashMap<String, Object>(); cache.put("key", value); 

Requirements

I need to extend the cache to include basic features like:

• Max size
• Time to live

However, I don't need more sophisticated features like:

• Access from multiple processes (caching server)
• Persistence (to disk)

Suggestions

In-Memory caching:

• Guava CacheBuilder - active development. See this presentation.
• LRUMap - Config via API. No TTL. Not purpose built for caching.
• whirlycache - XML config. Mailing list. Last updated 2006.
• cache4j - XML config. Documentation in Russian. Last updated 2006.

Enterprise caching:

• JCS - Properties config. Extensive documentation.
• Ehcache - XML config. Extensive documentation. By far the most popular according to Google hits.

Answer 1

EHCache is very nice. You can create an in memory cache. Check out their code samples for an example of creating an in memory cache. You can specify a max size, and a time to live.

EHCache does offer some advanced features, but if your not interested in using them - don't. But it's nice to know they are there if your requirements ever change.

Here is an in memory cache. Created in code, with no configuration files.

CacheManager cacheManager = CacheManager.getInstance(); int oneDay = 24 * 60 * 60; Cache memoryOnlyCache = new Cache("name", 200, false, false, oneDay, oneDay); cacheManager.addCache(memoryOnlyCache); 

Creates a cache that will hold 200 elements, and has a ttl of 24 hours.

Answer 2

I really like the MapMaker that comes with Google Guava (API)

The JavaDoc has a pretty neat example that demonstrates both its ease of use and its power:

ConcurrentMap<Key, Graph> graphs = new MapMaker()    .concurrencyLevel(32)    .softKeys()    .weakValues()    .expiration(30, TimeUnit.MINUTES)    .makeComputingMap(        new Function<Key, Graph>() {          public Graph apply(Key key) {            return createExpensiveGraph(key);          }        }); 

Furthermore, release 10.0 of Guava introduced the much more extensive com.google.common.cache package (there's a nice wiki entry on how to use them).