Getting an EhCache instance with Spring... intelligently - spring

Question

I need to get a specific EhCache instance by name and I'd prefer to autowire if possible. Given the following automatically configured controller, how can I autowire in the cache instance I'm looking for?
#Controller
public class MyUniqueService {
...
}
<beans ...>
<ctx:component-scan base-package="my.controllers"/>
<mvc:annotation-driven />
</beans>
How do I configure EhCache in my application context? I don't see any log messages from EhCache about it loading the ehcache.xml file in my /WEB-INF/ directory. How do I make it load it?
How can I integrate EhCache with my Spring application to have it load the ehcache.xml file from my /WEB-INF/ directory and autowire a cache by a given name into my MyUniqueService controller?

Answer 1

First you need to create a Ehcache CacheManager singleton in you app context like this:
<bean id="myEhCacheManager" class="org.springframework.cache.ehcache.EhCacheManagerFactoryBean">
<property name="configLocation" value="classpath:my-ehcache.xml"/>
</bean>
Here configLocation is set to load from classpath or use value="/WEB-INF/my-ehcache.xml".
In your controller simply inject the CacheManager instance:
#Controller
public class MyUniqueService {
#Resource(name="myEhCacheManager")
private CacheManager cacheManager;
...
}
Alternatively, if you'd like to go the "entirely autowired" route, do:
<bean class="org.springframework.cache.ehcache.EhCacheCacheManager">
<property name="cacheManager">
<bean class="org.springframework.cache.ehcache.EhCacheManagerFactoryBean">
<property name="configLocation" value="/WEB-INF/ehcache.xml"/>
</bean>
</property>
</bean>
Setup your class like so:
#Controller
public class MyUniqueService {
#Autowired
private org.springframework.cache.CacheManager cacheManager;
public org.springframework.cache.Cache getUniqueObjectCache() {
return cacheManager.getCache("uniqueObjectCache");
}
}
uniqueObjectCache corresponds to this cache instance in your ehcache.xml cache definition:
<cache name="uniqueObjectCache"
maxElementsInMemory="10000"
eternal="false"
timeToIdleSeconds="300"
timeToLiveSeconds="600"
memoryStoreEvictionPolicy="LRU"
transactionalMode="off"/>
There isn't a way to inject an actual cache instance, but as shown above, you can inject a cache manager and use it to get the cache you're interested in.

Answer 2

Assuming you have cacheManager defined:
<bean id="cacheManager"
class="org.springframework.cache.ehcache.EhCacheManagerFactoryBean">
<property name="configLocation" value="classpath:/ehcache.xml"/>
</bean>
You can get/inject specific cache like this:
#Value("#{cacheManager.getCache('myCacheName')}")
private Cache myCache;
See also examples how to use Spring EL inside the #Value() http://www.mkyong.com/spring3/spring-el-method-invocation-example/ if you are interested.

Answer 3

You can also use autowire if the context can find a bean with the correct class. Here is how I configured my xml
<bean id="cacheManager" class="org.springframework.cache.ehcache.EhCacheManagerFactoryBean">
<property name="configLocation">
<value>WEB-INF/ehcache.xml</value>
</property>
</bean>
<bean id="cache" class="net.sf.ehcache.Cache" factory-bean="cacheManager" factory-method="getCache">
<constructor-arg value="CacheNameHere" />
</bean>
And my java class
#Autowired
private net.sf.ehcache.Cache cache;
This setup works for me.

Answer 4

Indeed! Or if you want to use a java config class:
#Inject
private ResourceLoader resourceLoader;
#Bean
public CacheManager cacheManager() {
EhCacheCacheManager ehCacheCacheManager = new EhCacheCacheManager();
try {
ehCacheCacheManager.setCacheManager(ehcacheCacheManager().getObject());
} catch (Exception e) {
throw new IllegalStateException("Failed to create an EhCacheManagerFactoryBean", e);
}
return ehCacheCacheManager;
}
#Bean
public FactoryBean<net.sf.ehcache.CacheManager> ehcacheCacheManager() {
EhCacheManagerFactoryBean bean = new EhCacheManagerFactoryBean();
bean.setConfigLocation(resourceLoader.getResource("classpath:ehcache.xml"));
return bean;
}