使用ehcache-spring-annotations开启ehcache的注解功能

Spring 3.0.5的，更细颗粒化的缓存设置，更方便的注解，可以具体到把每个方式的返回值做缓存， 需要 ehcache-spring-annotations-1.1.x。

下载地址是：http://code.google.com/p/ehcache-spring-annotations

首先，applicationContext.xml 

 <beans xmlns="http://www.springframework.org/schema/beans"
  xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
  xmlns:aop="http://www.springframework.org/schema/aop"
  xmlns:context="http://www.springframework.org/schema/context"
  xmlns:p="http://www.springframework.org/schema/p"
  xmlns:tx="http://www.springframework.org/schema/tx"
  xmlns:ehcache="http://ehcache-spring-annotations.googlecode.com/svn/schema/ehcache-spring"
  xsi:schemaLocation="http://www.springframework.org/schema/beans
   http://www.springframework.org/schema/beans/spring-beans.xsd
   http://www.springframework.org/schema/aop
   http://www.springframework.org/schema/aop/spring-aop-3.0.xsd
   http://www.springframework.org/schema/context
   http://www.springframework.org/schema/context/spring-context-3.0.xsd
   http://www.springframework.org/schema/tx
   http://www.springframework.org/schema/tx/spring-tx-3.0.xsd
   http://ehcache-spring-annotations.googlecode.com/svn/schema/ehcache-spring
   http://ehcache-spring-annotations.googlecode.com/svn/schema/ehcache-spring/ehcache-spring-1.1.xsd">

 <ehcache:annotation-driven cache-manager="ehCacheManager" />

  <bean id="ehCacheManager" class="org.springframework.cache.ehcache.EhCacheManagerFactoryBean">
        <property name="configLocation" value="classpath:ehcache.xml" />
    </bean>

其次，src下的 ehcache.xml  

 <?xml version="1.0" encoding="UTF-8"?>
 <ehcache xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
  xsi:noNamespaceSchemaLocation="http://ehcache.org/ehcache.xsd"
  updateCheck="false">
  <diskStore path="java.io.tmpdir" />
  <defaultCache eternal="false"
    maxElementsInMemory="1000"
    overflowToDisk="false"
    diskPersistent="false"
    timeToIdleSeconds="0"
    timeToLiveSeconds="600"
    memoryStoreEvictionPolicy="LRU" />

  <cache name="departCache"
    eternal="false"
    maxElementsInMemory="100"
    overflowToDisk="false"
    diskPersistent="false"
    timeToIdleSeconds="0"
    timeToLiveSeconds="300"
    memoryStoreEvictionPolicy="LRU" />

 </ehcache>

DAO层缓存：例如下边这个方法的返回值需要缓存： 

@SuppressWarnings("unchecked") 
//spring 3 基于注解ehcache缓存配置; 
@Cacheable(cacheName="departCache") 
public List<AppDepart> getChildDepart(Integer id) throws Exception { 
  return  this.getHibernateTemplate().find("from AppDepart  where state=1 and idParent="+id); 
} 
@Cacheable(cacheName="departCache") 加上这句话，其中cacheName 对应ehcache.xml  中的<cache name="departCache" 
这样这个方法返回值就可以被缓存起来的了，但是怎么样把缓存数据和数据库中的数据实现同步呢？ 
如果对这个PO做update ,save,delete 可以实现这样策略如下： 
@Transactional(propagation = Propagation.REQUIRED) 
//设定spring的ecache缓存策略,当编辑机构时候,把缓存全部清除掉,以达到缓存那数据同步; 
@TriggersRemove(cacheName="departCache",removeAll=true) 
public boolean editDepart(String depno, String depName) { 
  boolean flag = false; 
  try { 
   AppDepart depart = departDao.getAppdepart(depno); 
   depart.setDepName(depName); 
   departDao.update(depart); 
   flag = true; 
  } catch (Exception e) { 
   e.printStackTrace(); 
  } 
  return flag; 
} 
好了到此配置完毕，但是更加详细缓存配置策略需要研究(例如：当update数据时候，不全部清掉缓存，就可以达到与数据库同步效果) 

使用 @Cacheable

public interface WeatherDao {
    
    public Weather getWeather(String zipCode);
    
    public List<Location> findLocations(String locationSearch);
}

public class DefaultWeatherDao implements WeatherDao {
    
    @Cacheable(cacheName="weatherCache")
    public Weather getWeather(String zipCode) {
        //Some Code
    }
    
    @Cacheable(cacheName="locationSearchCache")
    public List<Location> findLocations(String locationSearch) {
        //Some Code
    }
}

<!-- spring配置文件 --> 
<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
	xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
	xmlns:ehcache="http://ehcache-spring-annotations.googlecode.com/svn/schema/ehcache-spring"
	xsi:schemaLocation="http://www.springframework.org/schema/beans      
http://www.springframework.org/schema/beans/spring-beans-3.0.xsd      
http://ehcache-spring-annotations.googlecode.com/svn/schema/ehcache-spring      
http://ehcache-spring-annotations.googlecode.com/svn/schema/ehcache-spring/ehcache-spring-1.1.xsd">
	<ehcache:annotation-driven cache-manager="ehCacheManager" />
	<bean id="ehCacheManager"
		class="org.springframework.cache.ehcache.EhCacheManagerFactoryBean" />
	<bean id="weatherDao" class="x.y.service.DefaultWeatherDao" />
</beans>

<?xml version="1.0" encoding="UTF-8"?>
<ehcache xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xsi:noNamespaceSchemaLocation="http://ehcache.org/ehcache.xsd" updateCheck="false">
    <!--
     | Please see http://ehcache.sourceforge.net/documentation/configuration.html for
     | detailed information on how to configurigure caches in this file
     +-->
    <!-- Location of persistent caches on disk -->
    <diskStore path="java.io.tmpdir/EhCacheSpringAnnotationsExampleApp" />


    <defaultCache eternal="false" maxElementsInMemory="1000"
        overflowToDisk="false" diskPersistent="false" timeToIdleSeconds="0"
        timeToLiveSeconds="600" memoryStoreEvictionPolicy="LRU"/>


    <cache name="weatherCache" eternal="false"
        maxElementsInMemory="100" overflowToDisk="false" diskPersistent="false"
        timeToIdleSeconds="0" timeToLiveSeconds="300"
        memoryStoreEvictionPolicy="LRU" />


    <cache name="locationSearchCache" eternal="false"
        maxElementsInMemory="100" overflowToDisk="false" diskPersistent="false"
        timeToIdleSeconds="0" timeToLiveSeconds="300"
        memoryStoreEvictionPolicy="LRU" />
</ehcache>

表1. <ehcache:annotation-driven/> 设置

Attribute	Default	Description
cache-manager	cacheManager	The bean name of the CacheManager that is to be used to drive caching. This attribute is not required, and only needs to be specified explicitly if the bean name of the desired CacheManager is not 'cacheManager'.
create-missing-caches	false	Should cache names from @Cacheable annotations that don't exist in the CacheManager be created based on the default cache or should an exception be thrown?
default-cache-key-generator	Not Set	Default CacheKeyGenerator implementation to use. If not specified HashCodeCacheKeyGenerator will be used as the default.
self-populating-cache-scope	shared	Are the SelfPopulatingCache wrappers scoped to the method or are they shared among all methods using each self populating cache.
proxy-target-class	false	Applies to proxy mode only. Controls what type of caching proxies are created for classes annotated with the@Cacheable annotation. If the proxy-target-class attribute is set to true, then class-based proxies are created. If proxy-target-class is false or if the attribute is omitted, then standard JDK interface-based proxies are created. (See Spring Reference Section 7.6, “Proxying mechanisms” for a detailed examination of the different proxy types.)
order	Ordered.LOWEST_PRECEDENCE	Defines the order of the caching advice that is applied to beans annotated with @Cacheable. (For more information about the rules related to ordering of AOP advice, see Spring Reference Section 7.2.4.7, “Advice ordering”.) No specified ordering means that the AOP subsystem determines the order of the advice.

@Cacheable设置

Property	Type	Description
cacheName	String	Required name of the cache to use
selfPopulating	boolean	Optional if the method should have self-populating semantics. This results in calls to the annotated method to be made within a EhCache CacheEntryFactory. This is useful for expensive shared resources that should be retrieved a minimal number of times.
keyGenerator	@KeyGenerator	Optional inline configuration of a CacheKeyGenerator to use for generating cache keys for this method.
keyGeneratorName	String	Optional bean name of a CacheKeyGenerator to use for generating cache keys for this method.
exceptionCacheName	String	Optional name of the cache to use for caching exceptions. If not specified exceptions result in nothing being cached. If specified the thrown exception is stored in the cache for the generated key and re-thrown for subsequent method calls as long as it remains in the exception cache.