如果在網(wǎng)上查找使用Spring 3.1內(nèi)置緩存的示例，那么通常會(huì)碰到Spring的SimpleCacheManager ，Spring的家伙說這對(duì)“用于測(cè)試或簡(jiǎn)單的緩存聲明很有用”。 實(shí)際上，我更喜歡將SimpleCacheManager看作是輕量級(jí)的，而不是簡(jiǎn)單的。 在您希望每個(gè)JVM占用少量?jī)?nèi)存緩存的情況下很有用。 如果Spring的家伙正在經(jīng)營(yíng)一家超市，那么SimpleCacheManager將屬于他們自己品牌的“基本”產(chǎn)品范圍。

另一方面，如果您需要一個(gè)可擴(kuò)展，持久和分布式的重型緩存，則Spring還附帶內(nèi)置的ehCache包裝器。

好消息是，Spring的緩存實(shí)現(xiàn)之間的交換很容易。 從理論上講，這完全是配置問題，為了證明該理論正確，我從Caching和@Cacheable博客中獲取了示例代碼，并使用EhCache實(shí)現(xiàn)對(duì)其進(jìn)行了運(yùn)行。

配置步驟與我上一篇博客“ 緩存和配置”中描述的步驟相似，您仍然需要指定：

<cache:annotation-driven />

…在您的Spring配置文件中以打開緩存。 您還需要定義一個(gè)id為cacheManager的bean，只是這一次您引用Spring的EhCacheCacheManager類而不是SimpleCacheManager 。

<bean id='cacheManager'class='org.springframework.cache.ehcache.EhCacheCacheManager'p:cacheManager-ref='ehcache'/>

上面的示例演示了EhCacheCacheManager配置。 注意，它引用了另一個(gè)ID為“ ehcache ”的bean。 配置如下：

<bean id='ehcache' class='org.springframework.cache.ehcache.EhCacheManagerFactoryBean'p:configLocation='ehcache.xml'p:shared='true'/>

“ ehcache ”具有兩個(gè)屬性： configLocation和shared 。
“ configLocation ”是一個(gè)可選屬性，用于指定ehcache配置文件的位置。 在測(cè)試代??碼中，我使用了以下示例文件：

<?xml version='1.0' encoding='UTF-8'?> <ehcache xmlns:xsi='http://www.w3.org/2001/XMLSchema-instance' xsi:noNamespaceSchemaLocation='http://ehcache.org/ehcache.xsd'><defaultCache eternal='true' maxElementsInMemory='100' overflowToDisk='false' /><cache name='employee' maxElementsInMemory='10000' eternal='true' overflowToDisk='false' /> </ehcache>

…這將創(chuàng)建兩個(gè)緩存：一個(gè)默認(rèn)緩存和一個(gè)名為“員工”的緩存。

如果缺少此文件，則EhCacheManagerFactoryBean只需選擇一個(gè)默認(rèn)的ehcache配置文件： ehcache-failsafe.xml ，該文件位于ehcache的ehcache-core jar文件中。

另一個(gè)EhCacheManagerFactoryBean屬性是' shared '。 這被認(rèn)為是可選的，因?yàn)槲臋n指出它定義了“ EHCache CacheManager是應(yīng)該共享（作為VM級(jí)別的單例）還是獨(dú)立的（通常在應(yīng)用程序內(nèi)部）。 默認(rèn)值為'false'，創(chuàng)建一個(gè)獨(dú)立的實(shí)例。” 但是，如果將其設(shè)置為false，則將收到以下異常：

org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'org.springframework.cache.interceptor.CacheInterceptor#0': Cannot resolve reference to bean 'cacheManager' while setting bean property 'cacheManager'; nested exception is org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'cacheManager' defined in class path resource [ehcache-example.xml]: Cannot resolve reference to bean 'ehcache' while setting bean property 'cacheManager'; nested exception is org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'ehcache' defined in class path resource [ehcache-example.xml]: Invocation of init method failed; nested exception is net.sf.ehcache.CacheException: Another unnamed CacheManager already exists in the same VM. Please provide unique names for each CacheManager in the config or do one of following: 1. Use one of the CacheManager.create() static factory methods to reuse same CacheManager with same name or create one if necessary 2. Shutdown the earlier cacheManager before creating new one with same name. The source of the existing CacheManager is: InputStreamConfigurationSource [stream=java.io.BufferedInputStream@424c414]at org.springframework.beans.factory.support.BeanDefinitionValueResolver. resolveReference(BeanDefinitionValueResolver.java:328)at org.springframework.beans.factory.support.BeanDefinitionValueResolver. resolveValueIfNecessary(BeanDefinitionValueResolver.java:106)at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory. applyPropertyValues(AbstractAutowireCapableBeanFactory.java:1360)at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory. populateBean(AbstractAutowireCapableBeanFactory.java:1118)at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory. doCreateBean(AbstractAutowireCapableBeanFactory.java:517)at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory. createBean(AbstractAutowireCapableBeanFactory.java:456) ... stack trace shortened for clarityat org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner. java:683)at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner. run(RemoteTestRunner.java:390)at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner. main(RemoteTestRunner.java:197) Caused by: org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'cacheManager' defined in class path resource [ehcache-example.xml]: Cannot resolve reference to bean 'ehcache' while setting bean property 'cacheManager'; nested exception is org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'ehcache' defined in class path resource [ehcache-example.xml]: Invocation of init method failed; nested exception is net.sf.ehcache.CacheException: Another unnamed CacheManager already exists in the same VM. Please provide unique names for each CacheManager in the config or do one of following: 1. Use one of the CacheManager.create() static factory methods to reuse same CacheManager with same name or create one if necessary 2. Shutdown the earlier cacheManager before creating new one with same name. The source of the existing CacheManager is: InputStreamConfigurationSource [stream=java.io.BufferedInputStream@424c414]at org.springframework.beans.factory.support.BeanDefinitionValueResolver. resolveReference(BeanDefinitionValueResolver.java:328)at org.springframework.beans.factory.support.BeanDefinitionValueResolver. resolveValueIfNecessary(BeanDefinitionValueResolver.java:106)at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory. applyPropertyValues(AbstractAutowireCapableBeanFactory.java:1360) ... stack trace shortened for clarityat org.springframework.beans.factory.support.AbstractBeanFactory. getBean(AbstractBeanFactory.java:193)at org.springframework.beans.factory.support.BeanDefinitionValueResolver. resolveReference(BeanDefinitionValueResolver.java:322)... 38 more Caused by: org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'ehcache' defined in class path resource [ehcache-example.xml]: Invocation of init method failed; nested exception is net.sf.ehcache.CacheException: Another unnamed CacheManager already exists in the same VM. Please provide unique names for each CacheManager in the config or do one of following: 1. Use one of the CacheManager.create() static factory methods to reuse same CacheManager with same name or create one if necessary 2. Shutdown the earlier cacheManager before creating new one with same name. The source of the existing CacheManager is: InputStreamConfigurationSource [stream=java.io.BufferedInputStream@424c414]at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory. initializeBean(AbstractAutowireCapableBeanFactory.java:1455)at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory. doCreateBean(AbstractAutowireCapableBeanFactory.java:519)at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory. createBean(AbstractAutowireCapableBeanFactory.java:456)at org.springframework.beans.factory.support.AbstractBeanFactory$1 .getObject(AbstractBeanFactory.java:294)at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry. getSingleton(DefaultSingletonBeanRegistry.java:225)at org.springframework.beans.factory.support.AbstractBeanFactory. doGetBean(AbstractBeanFactory.java:291)at org.springframework.beans.factory.support.AbstractBeanFactory. getBean(AbstractBeanFactory.java:193)at org.springframework.beans.factory.support.BeanDefinitionValueResolver. resolveReference(BeanDefinitionValueResolver.java:322)... 48 more Caused by: net.sf.ehcache.CacheException: Another unnamed CacheManager already exists in the same VM. Please provide unique names for each CacheManager in the config or do one of following: 1. Use one of the CacheManager.create() static factory methods to reuse same CacheManager with same name or create one if necessary 2. Shutdown the earlier cacheManager before creating new one with same name. The source of the existing CacheManager is: InputStreamConfigurationSource [stream=java.io.BufferedInputStream@424c414]at net.sf.ehcache.CacheManager.assertNoCacheManagerExistsWithSameName(CacheManager. java:521)at net.sf.ehcache.CacheManager.init(CacheManager.java:371)at net.sf.ehcache.CacheManager.(CacheManager.java:339)at org.springframework.cache.ehcache.EhCacheManagerFactoryBean. afterPropertiesSet(EhCacheManagerFactoryBean.java:104)at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory. invokeInitMethods(AbstractAutowireCapableBeanFactory.java:1514)at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory. initializeBean(AbstractAutowireCapableBeanFactory.java:1452)... 55 more

…當(dāng)您嘗試運(yùn)行一系列單元測(cè)試時(shí)。

我認(rèn)為這歸結(jié)為Spring的ehcache管理器工廠的一個(gè)簡(jiǎn)單錯(cuò)誤，因?yàn)樗噲D使用new()創(chuàng)建多個(gè)緩存實(shí)例，而不是使用“其中一種CacheManager.create（）靜態(tài)工廠方法”作為例外，允許其重用相同名稱的相同CacheManager。 因此，我的第一個(gè)JUnit測(cè)試工作正常，但其他所有測(cè)試均失敗。

令人反感的代碼行是：

this.cacheManager = (this.shared ? CacheManager.create() : new CacheManager());

為了完整性，下面列出了我的完整XML配置文件：

<?xml version='1.0' encoding='UTF-8'?> <beans xmlns='http://www.springframework.org/schema/beans' xmlns:p='http://www.springframework.org/schema/p'xmlns:xsi='http://www.w3.org/2001/XMLSchema-instance'xmlns:cache='http://www.springframework.org/schema/cache' xmlns:context='http://www.springframework.org/schema/context'xsi:schemaLocation='http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsdhttp://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context-3.1.xsdhttp://www.springframework.org/schema/cache http://www.springframework.org/schema/cache/spring-cache.xsd'><!-- Switch on the Caching --><cache:annotation-driven /><!-- Do the component scan path --><context:component-scan base-package='caching' /><bean id='cacheManager' class='org.springframework.cache.ehcache.EhCacheCacheManager' p:cacheManager-ref='ehcache'/><bean id='ehcache' class='org.springframework.cache.ehcache.EhCacheManagerFactoryBean' p:configLocation='ehcache.xml' p:shared='true'/> </beans>

在使用ehcache時(shí)，要考慮的唯一其他配置詳細(xì)信息是Maven依賴項(xiàng)。 這些非常簡(jiǎn)單，因?yàn)镋hcache的專家們將所有各種ehcache jar組合到一個(gè)Maven POM模塊中。 可以使用下面的XML將該P(yáng)OM模塊添加到項(xiàng)目的POM文件中：

<dependency><groupId>net.sf.ehcache</groupId><artifactId>ehcache</artifactId><version>2.6.0</version><type>pom</type><scope>test</scope></dependency>

最后，可以從Maven Central和Sourceforge存儲(chǔ)庫中獲得ehcache Jar文件：

<repositories><repository><id>sourceforge</id><url>http://oss.sonatype.org/content/groups/sourceforge/</url><releases><enabled>true</enabled></releases><snapshots><enabled>true</enabled></snapshots></repository></repositories>

祝您編程愉快，別忘了分享！

參考： Spring 3.1：來自Captain Debug's Blog博客的JCG合作伙伴 Roger Hughes的緩存和EhCache 。

翻譯自: https://www.javacodegeeks.com/2012/10/spring-31-caching-and-ehcache.html

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