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copied!<p>Yes, using Ehcache, you can configure your caches and retrieve their sizes by Java code only (no XML config). The exact way to integrate everything depends on your specific architecture; I'm going to assume Jersey for doing API stuff and Guice for dependency injection.</p> <p><strong>Defining your cache</strong></p> <p>Make your cache manager available via dependency injection. This can be done via a Guice module:</p> <pre><code>@Provides @Singleton CacheManager provideCacheManager() { CacheManager cacheManager = CacheManager.create(); /* very basic cache configuration */ CacheConfiguration config = new CacheConfiguration("mycache", 100) .timeToLiveSeconds(60) .timeToIdleSeconds(30) .statistics(true); Cache myCache = new Cache(config); cacheManager.addCacheIfAbsent(myCache); return cacheManager; } </code></pre> <p>Notice that statistics is turned on for <code>mycache</code>.</p> <p>Again, using your cache can be done entirely in Java code but depends on your architecture and design. Typically I do this using method interception (via AOP) but that's another topic.</p> <p><strong>Fetch cache stats via REST API</strong></p> <p>Given your <code>CacheManager</code> is available via dependency injection you can then wire it up to a REST endpoint and allow access to cache statistics:</p> <pre><code>@Path("stats") @Produces("text/plain") public class StatsResource { @Inject private CacheManager cacheManager; @GET public String stats() { StringBuffer sb = StringBuffer(); /* get stats for all known caches */ for (String name : cacheManager.getCacheNames()) { Cache cache = cacheManager.getCache(name); Statistics stats = cache.getStatistics(); sb.append(String.format("%s: %s objects, %s hits, %s misses\n", name, stats.getObjectCount(), stats.getCacheHits(), stats.getCacheMisses() )); } return sb.toString(); } } </code></pre> <p>Now you can fetch information about your caches by REST call:</p> <pre><code>GET /stats HTTP/1.1 200 OK Content-Type: text/plain; charset=utf-8 mycache: 8 objects, 59 hits, 12 misses </code></pre> <p><strong>What about JMX?</strong></p> <p>Ehcache makes it easy to register your cache manger with an MBean server. It can be done in Java code. Update your Guice module, registering your <code>cacheManager</code> to the system <code>MBeanServer</code>:</p> <pre><code>MBeanServer mBeanServer = ManagementFactory.getPlatformMBeanServer(); ManagementService.registerMBeans(cacheManager, mBeanServer, false, false, false, true); </code></pre> <p>Now you can attach JConsole to your Java process and find your cache statistics in the MBean <code>net.sf.ehcache.CacheStatistics</code>.</p>

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