Lightweight Java Object cache API

Chase_Seibert_7679 0
Viewed 77317

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.
caching java
7 Answers

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.

user_7390
user_1055620

You can check out LinkedHashMap to implement a simple cache without third party jars:

    Map <String, Foo> cache = new LinkedHashMap<String, Foo>(MAX_ENTRIES + 1, .75F, true) {

        public boolean removeEldestEntry(Map.Entry<String, Foo> eldest) {
            return size() > MAX_ENTRIES;
        }
    };

then you can get from the cache like

    Foo foo = cache.get(key);
    if (foo == null && !cache.containsKey(key)) {
        try {
            FooDAO fooDAO = DAOFactory.getFooDAO(conn);
            foo = fooDAO.getFooByKey(key);
            cache.put(key, foo);
        } catch (SQLException sqle) {
            logger.error("[getFoo] SQL Exception when accessing Foo", sqle);
        }
    }

rest left as exercise for reader :)

JeeBee_178320

JCS is tried and true. Even though it is light as far as caching mechanisms go, you might dig into the actual code and mimic what they do with HashMap under the covers to exactly what you need and no more. You seem to have a pretty good idea of what you are looking for.

Ichorus_272470
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