Spring中报"Could not resolve placeholder"的错误

错误描述：除去properites文件路径错误、拼写错误外，出现”Could not resolve placeholder”很有可能是使用了多个PropertyPlaceholderConfigurer或者多个的原因。

严重: Exception sending context initialized event to listener instance of class org.springframework.web.context.ContextLoaderListener
org.springframework.beans.factory.BeanDefinitionStoreException: Invalid bean definition with name ‘com.alibaba.dubbo.config.RegistryConfig’ defined in null: Could not resolve placeholder ‘dubbo.registry’ in value “[Math Processing Error] d u b b o . r e g i s t r y " ; n e s t e d e x c e p t i o n i s j a v a . l a n g . I l l e g a l A r g u m e n t E x c e p t i o n : C o u l d n o t r e s o l v e p l a c e h o l d e r ′ d u b b o . r e g i s t r y ′ i n v a l u e " {dubbo.registry}”
at org.springframework.beans.factory.config.PlaceholderConfigurerSupport.doProcessProperties(PlaceholderConfigurerSupport.java:223)
at org.springframework.context.support.PropertySourcesPlaceholderConfigurer.processProperties(PropertySourcesPlaceholderConfigurer.java:180)
at org.springframework.context.support.PropertySourcesPlaceholderConfigurer.postProcessBeanFactory(PropertySourcesPlaceholderConfigurer.java:152)
at org.springframework.context.support.PostProcessorRegistrationDelegate.invokeBeanFactoryPostProcessors(PostProcessorRegistrationDelegate.java:283)
at org.springframework.context.support.PostProcessorRegistrationDelegate.invokeBeanFactoryPostProcessors(PostProcessorRegistrationDelegate.java:163)
at org.springframework.context.support.AbstractApplicationContext.invokeBeanFactoryPostProcessors(AbstractApplicationContext.java:687)
at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:525)
at org.springframework.web.context.ContextLoader.configureAndRefreshWebApplicationContext(ContextLoader.java:443)
at org.springframework.web.context.ContextLoader.initWebApplicationContext(ContextLoader.java:325)
at org.springframework.web.context.ContextLoaderListener.contextInitialized(ContextLoaderListener.java:107)
at org.apache.catalina.core.StandardContext.listenerStart(StandardContext.java:5157)
at org.apache.catalina.core.StandardContext.startInternal(StandardContext.java:5680)
at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:145)
at org.apache.catalina.core.ContainerBase StartChild.call(ContainerBase.java:1702)atorg.apache.catalina.core.ContainerBase S t a r t C h i l d . c a l l ( C o n t a i n e r B a s e . j a v a : 1702 ) a t o r g . a p a c h e . c a t a l i n a . c o r e . C o n t a i n e r B a s e StartChild.call(ContainerBase.java:1692)
at java.util.concurrent.FutureTask.run(FutureTask.java:266)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149)
at java.util.concurrent.ThreadPoolExecutor[Math Processing Error] W o r k e r . r u n ( T h r e a d P o o l E x e c u t o r . j a v a : 624 ) a t j a v a . l a n g . T h r e a d . r u n ( T h r e a d . j a v a : 748 ) C a u s e d b y : j a v a . l a n g . I l l e g a l A r g u m e n t E x c e p t i o n : C o u l d n o t r e s o l v e p l a c e h o l d e r ‘ d u b b o . r e g i s t r y ′ i n v a l u e “ {dubbo.registry}”
at org.springframework.util.PropertyPlaceholderHelper.parseStringValue(PropertyPlaceholderHelper.java:174)
at org.springframework.util.PropertyPlaceholderHelper.replacePlaceholders(PropertyPlaceholderHelper.java:126)
at org.springframework.core.env.AbstractPropertyResolver.doResolvePlaceholders(AbstractPropertyResolver.java:236)
at org.springframework.core.env.AbstractPropertyResolver.resolveRequiredPlaceholders(AbstractPropertyResolver.java:210)
at org.springframework.context.support.PropertySourcesPlaceholderConfigurer$2.resolveStringValue(PropertySourcesPlaceholderConfigurer.java:172)
at org.springframework.beans.factory.config.BeanDefinitionVisitor.resolveStringValue(BeanDefinitionVisitor.java:282)
at org.springframework.beans.factory.config.BeanDefinitionVisitor.resolveValue(BeanDefinitionVisitor.java:209)
at org.springframework.beans.factory.config.BeanDefinitionVisitor.visitPropertyValues(BeanDefinitionVisitor.java:141)
at org.springframework.beans.factory.config.BeanDefinitionVisitor.visitBeanDefinition(BeanDefinitionVisitor.java:82)
at org.springframework.beans.factory.config.PlaceholderConfigurerSupport.doProcessProperties(PlaceholderConfigurerSupport.java:220)
… 18 more

解决方案：
spring版本4.3.14

   
<context:property-placeholder location="config/db.properties" ignore-unresolvable="true" />  

  
<context:property-placeholder location="config/resource.properties" ignore-unresolvable="true" />  

在applicationContext-dao.xml和applicationContext-service.xml中添加 ignore-unresolvable=”true”