Spring中報"Could not resolve placeholder"的錯誤

錯誤描述：除去properites文件路徑錯誤、拼寫錯誤外，出現”Could not resolve placeholder”很有可能是使用了多個PropertyPlaceholderConfigurer或者多個的原因。

嚴重: 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]$dubbo.registry";nestedexceptionisjava.lang.IllegalArgumentException:Couldnotresolveplaceholde{r}^{\prime }dubbo.registr{y}^{\prime }invalue"$ {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.ContainerBaseStartChild.call(ContainerBase.java:1702)atorg.apache.catalina.core.ContainerBase$StartChild.call(ContainerBase.java:1702)atorg.apache.catalina.core.ContainerBase$ 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]$Worker.run(ThreadPoolExecutor.java:624)atjava.lang.Thread.run(Thread.java:748)Causedby:java.lang.IllegalArgumentException:Couldnotresolveplaceholder‘dubbo.registr{y}^{\prime }invalue“$ {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

解決方案：
spring版本4.3.14

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

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

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