ehcache persist to disk issues

Question

I want to do something with ehcache in Java that I think should be extremely simple, but I\'ve spent enough time frustrating myself with the docs...

1. Write a

Answer 1

I think you should remove the manager.cacheExists(..) test and simply create your cache using testCache = manager.getCache("test"); instead of using new Cache(..). Even if your cache is diskPersistent, it won't exist until you get it the first time. (At least that's what I think as I'm only using getCache(..) and it does exactly what you are looking for)

Note:

You could also add something like this to make sure the cache exists:

Cache cache = manager.getCache(name);
if (cache == null) {
    throw new NullPointerException(String.format("no cache with name %s defined, please configure it in %s", name, url));
}

Note 2:

If your configuration file is called ehcache.xml, you shouldn't use CacheManager.create(url). Instead use the CacheManager singleton: I think I've confused using CacheManager.create(url) with and using new CacheManager(url). Still, you should use the singleton for ehcache.xml and new CacheManager(url) for anything else.

// ehcache.xml - shared between different invocations
CacheManager defaultManager = CacheManager.getInstance();
// others - avoid calling twice with same argument
CacheManager manager = CacheManager.create(url);

Using CacheManager.create(..) is problematic as it might completely ignore the passed URL if any of the create(..) methods or getInstance() have been called before:

public static CacheManager create(URL configurationFileURL) throws CacheException {
    synchronized (CacheManager.class) {
        if (singleton == null) {
            if (LOG.isDebugEnabled()) {
                LOG.debug("Creating new CacheManager with config URL: " + configurationFileURL);
            }
            singleton = new CacheManager(configurationFileURL);

        }
        return singleton;
    }
}

That's why I wouldn't recommend using any of the CacheManager.create(..) methods. Use CacheManager.getInstance() or new CacheManager(url).