A Footnote on Accessing Request Parameters using Spring 3 MVC

I recently got a comment on my blog: Accessing Request Parameters using Spring 3 MVC, pointing out something that I didn’t know about Spring’s @RequestParam annotation. The comment, from salient1, went like this:

Spring 3.1: Caching and EhCache

If you look around the web for examples of using Spring 3.1’s built in caching then you’ll usually bump into Spring’s SimpleCacheManager, which the Guys at Spring say is “Useful for testing or simple caching declarations”. I actually prefer to think of SimpleCacheManager as lightweight rather than simple; useful in those situations where you want a small in memory cache on a per JVM basis. If the Guys at Spring were running a supermarket then SimpleCacheManagerwould be in their own brand ‘basics’ product range.

If, on the other hand, you need a heavy duty cache, one that’s scalable, persistent and distributed, then Spring also comes with a built in ehCache wrapper.

Spring 3.1 Caching and Config

I’ve recently being blogging about Spring 3.1 and its new caching annotations @Cacheable and @CacheEvict. As with all Spring features you need to do a certain amount of setup and, as usual, this is done with Spring’s XML configuration file. In the case of caching, turning on @Cacheable and @CacheEvict couldn’t be simpler as all you need to do is to add the following to your Spring config file:

   <cache:annotation-driven />

Spring 3.1 Caching and @CacheEvict

My last blog demonstrated the application of Spring 3.1’s @Cacheable annotation that’s used to mark methods whose return values will be stored in a cache. However, @Cacheable is only one of a pair of annotations that the Guys at Spring have devised for caching, the other being @CacheEvict.

Like @Cacheable, @CacheEvict has value, key and condition attributes. These work in exactly the same way as those supported by @Cacheable, so for more information on them see my previous blog: Spring 3.1 Caching and @Cacheable.

@CacheEvict supports two additional attributes: allEntries and beforeInvocation. If I were a gambling man I'd put money on the most popular of these being allEntries. allEntries is used to completely clear the contents of a cache defined by @CacheEvict's mandatory value argument. The method below demonstrates how to apply allEntries:

Spring 3.1 Caching and @Cacheable

Caches have been around in the software world for long time. They’re one of those really useful things that once you start using them you wonder how on earth you got along without them so, it seems a little strange that the Guys at Spring only got around to adding a caching implementation to Spring core in version 3.1. I’m guessing that previously it wasn’t seen as a priority and besides, before the introduction of Java annotations, one of the difficulties of caching was the coupling of caching code with your business code, which could often become pretty messy.

However, the Guys at Spring have now devised a simple to use caching system based around a couple of annotations: @Cacheable and @CacheEvict.