在 ehcache.xml 中访问 spring 环境变量

Question

我想访问 ehcache.xml 中的 Spring 环境变量，但出现以下错误。

    org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'cacheManager' defined in class path resource [com/cache.xml]: Invocation of init method failed; nested exception is net.sf.ehcache.CacheException: Error configuring from input stream. Initial cause was null:166: Could not set attribute "maxElementsInMemory" - For input string: "${cache.report.maxMemoryElements}"
        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.DefaultListableBeanFactory.preInstantiateSingletons(DefaultListableBeanFactory.java:567)
        at org.springframework.context.support.AbstractApplicationContext.finishBeanFactoryInitialization(AbstractApplicationContext.java:913)
        at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:464)
        at org.springframework.web.context.ContextLoader.configureAndRefreshWebApplicationContext(ContextLoader.java:385)
        at org.springframework.web.context.ContextLoader.initWebApplicationContext(ContextLoader.java:284)
        at org.springframework.web.context.ContextLoaderListener.contextInitialized(ContextLoaderListener.java:111)
        at org.apache.catalina.core.StandardContext.listenerStart(StandardContext.java:4994)
        at org.apache.catalina.core.StandardContext.startInternal(StandardContext.java:5492)
        at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:150)
        at org.apache.catalina.core.ContainerBase.addChildInternal(ContainerBase.java:901)
        at org.apache.catalina.core.ContainerBase.addChild(ContainerBase.java:877)
        at org.apache.catalina.core.StandardHost.addChild(StandardHost.java:649)
        at 

org.apache.catalina.startup.HostConfig.deployDescriptor(HostConfig.java:672)
        at org.apache.catalina.startup.HostConfig$DeployDescriptor.run(HostConfig.java:1861)
        at java.util.concurrent.Executors$RunnableAdapter.call(Unknown Source)
        at java.util.concurrent.FutureTask.run(Unknown Source)
        at java.util.concurrent.ThreadPoolExecutor.runWorker(Unknown Source)
        at java.util.concurrent.ThreadPoolExecutor$Worker.run(Unknown Source)
        at java.lang.Thread.run(Unknown Source)

我还运行了下面的测试，它表明系统属性可用于 ehcache.xml。任何想法？谢谢。

 @Test
  public void testLoadConfigurationWithReplacement() throws Exception {
    System.setProperty("cache.report.maxMemoryElements", "4446");
    CacheManager manager = CacheManager.newInstance(TEST_CONFIG_DIR + "ehcache.xml");
    System.out.print("caches: " + manager.getCacheNames());
    assertEquals(manager.getCache("reportCache").getCacheConfiguration().getMaxEntriesLocalHeap(), 4446);

  }

Answer 1

Ehcache 属性占位符是从系统属性中解析出来的，而 Spring 属性抽象使用多个来源，即系统属性、属性文件和系统环境。

您的第一个选项是在运行应用程序时使用系统属性，即 -Dcache.report.maxMemoryElements=4446

如果这不是一个选项并且您确实需要使用 Spring 属性文件，您可以实现一个 BeanFactoryPostProcessor，它将您的 Spring prperties 文件复制到系统属性中。例如

    public class  EhachePropertiesReplacer implements BeanFactoryPostProcessor , EnvironmentAware{

       private Environment environment;

       private List<String> ehcachePropertyNames;

       public void setEhcahePropertyNames(List<String> ehcachePropertyNames){
          this.ehcachePropertyNames = ehcachePropertyNames;
       }

       public void setEnvironment(Environment environment){
          this.environment = environment;
       }

       public void postProcessBeanFactory(ConfigurableBeanFactory bf){
          for(String ehcahePropertyName : ehcahePropetyNames){
             String ehcachePropertyValue = evironment.getProperty(ehcahePropertyName);
             System.setProperty(ehcahePropertyName ,ehcachePropertyValue);
          }      
       }
   }

}

然后在你的配置文件中

<bean class= "whatever.the.package.EhachePropertiesReplacer">
  <property name="ehachePropertyNames">
     <list>
        <value>cache.report.maxMemoryElements</value>
     </list>
  </property>
</bean>