Could not resolve placeholder 'driverClassName' in string value "${driverClassName}"

1、错误描述

信息: Initializing Spring root WebApplicationContext
2017-02-09 16:40:53,812 [localhost-startStop-1] ERROR [org.springframework.web.context.ContextLoader] - Context initialization failed
  org.springframework.beans.factory.BeanDefinitionStoreException: Invalid bean definition with name 'dataSource' defined in URL [file:/F:/Tomcat/apache-tomcat-7.0.69/webapps/cmp/WEB-INF/classes/ApplicationContext.xml]: Could not resolve placeholder 'driverClassName' in string value "${driverClassName}"; nested exception is java.lang.IllegalArgumentException: Could not resolve placeholder 'driverClassName' in string value "${driverClassName}"
	at org.springframework.beans.factory.config.PlaceholderConfigurerSupport.doProcessProperties(PlaceholderConfigurerSupport.java:223)
	at org.springframework.beans.factory.config.PropertyPlaceholderConfigurer.processProperties(PropertyPlaceholderConfigurer.java:222)
	at org.springframework.beans.factory.config.PropertyResourceConfigurer.postProcessBeanFactory(PropertyResourceConfigurer.java:86)
	at org.springframework.context.support.PostProcessorRegistrationDelegate.invokeBeanFactoryPostProcessors(PostProcessorRegistrationDelegate.java:281)
	at org.springframework.context.support.PostProcessorRegistrationDelegate.invokeBeanFactoryPostProcessors(PostProcessorRegistrationDelegate.java:161)
	at org.springframework.context.support.AbstractApplicationContext.invokeBeanFactoryPostProcessors(AbstractApplicationContext.java:686)
	at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:524)
	at org.springframework.web.context.ContextLoader.configureAndRefreshWebApplicationContext(ContextLoader.java:444)
	at org.springframework.web.context.ContextLoader.initWebApplicationContext(ContextLoader.java:326)
	at org.springframework.web.context.ContextLoaderListener.contextInitialized(ContextLoaderListener.java:107)
	at org.apache.catalina.core.StandardContext.listenerStart(StandardContext.java:5068)
	at org.apache.catalina.core.StandardContext.startInternal(StandardContext.java:5584)
	at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:147)
	at org.apache.catalina.core.ContainerBase.addChildInternal(ContainerBase.java:899)
	at org.apache.catalina.core.ContainerBase.addChild(ContainerBase.java:875)
	at org.apache.catalina.core.StandardHost.addChild(StandardHost.java:652)
	at org.apache.catalina.startup.HostConfig.deployDirectory(HostConfig.java:1260)
	at org.apache.catalina.startup.HostConfig$DeployDirectory.run(HostConfig.java:2002)
	at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:471)
	at java.util.concurrent.FutureTask.run(FutureTask.java:262)
	at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1145)
	at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:615)
	at java.lang.Thread.run(Thread.java:745)
Caused by: java.lang.IllegalArgumentException: Could not resolve placeholder 'driverClassName' in string value "${driverClassName}"
	at org.springframework.util.PropertyPlaceholderHelper.parseStringValue(PropertyPlaceholderHelper.java:174)
	at org.springframework.util.PropertyPlaceholderHelper.replacePlaceholders(PropertyPlaceholderHelper.java:126)
	at org.springframework.beans.factory.config.PropertyPlaceholderConfigurer$PlaceholderResolvingStringValueResolver.resolveStringValue(PropertyPlaceholderConfigurer.java:258)
	at org.springframework.beans.factory.config.BeanDefinitionVisitor.resolveStringValue(BeanDefinitionVisitor.java:282)
	at org.springframework.beans.factory.config.BeanDefinitionVisitor.resolveValue(BeanDefinitionVisitor.java:204)
	at org.springframework.beans.factory.config.BeanDefinitionVisitor.visitPropertyValues(BeanDefinitionVisitor.java:141)
	at org.springframework.beans.factory.config.BeanDefinitionVisitor.visitBeanDefinition(BeanDefinitionVisitor.java:82)
	at org.springframework.beans.factory.config.PlaceholderConfigurerSupport.doProcessProperties(PlaceholderConfigurerSupport.java:220)
	... 22 more
二月 09, 2017 4:40:53 下午 org.apache.catalina.core.StandardContext listenerStart
严重: Exception sending context initialized event to listener instance of class org.springframework.web.context.ContextLoaderListener
org.springframework.beans.factory.BeanDefinitionStoreException: Invalid bean definition with name 'dataSource' defined in URL [file:/F:/Tomcat/apache-tomcat-7.0.69/webapps/cmp/WEB-INF/classes/ApplicationContext.xml]: Could not resolve placeholder 'driverClassName' in string value "${driverClassName}"; nested exception is java.lang.IllegalArgumentException: Could not resolve placeholder 'driverClassName' in string value "${driverClassName}"
	at org.springframework.beans.factory.config.PlaceholderConfigurerSupport.doProcessProperties(PlaceholderConfigurerSupport.java:223)
	at org.springframework.beans.factory.config.PropertyPlaceholderConfigurer.processProperties(PropertyPlaceholderConfigurer.java:222)
	at org.springframework.beans.factory.config.PropertyResourceConfigurer.postProcessBeanFactory(PropertyResourceConfigurer.java:86)
	at org.springframework.context.support.PostProcessorRegistrationDelegate.invokeBeanFactoryPostProcessors(PostProcessorRegistrationDelegate.java:281)
	at org.springframework.context.support.PostProcessorRegistrationDelegate.invokeBeanFactoryPostProcessors(PostProcessorRegistrationDelegate.java:161)
	at org.springframework.context.support.AbstractApplicationContext.invokeBeanFactoryPostProcessors(AbstractApplicationContext.java:686)
	at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:524)
	at org.springframework.web.context.ContextLoader.configureAndRefreshWebApplicationContext(ContextLoader.java:444)
	at org.springframework.web.context.ContextLoader.initWebApplicationContext(ContextLoader.java:326)
	at org.springframework.web.context.ContextLoaderListener.contextInitialized(ContextLoaderListener.java:107)
	at org.apache.catalina.core.StandardContext.listenerStart(StandardContext.java:5068)
	at org.apache.catalina.core.StandardContext.startInternal(StandardContext.java:5584)
	at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:147)
	at org.apache.catalina.core.ContainerBase.addChildInternal(ContainerBase.java:899)
	at org.apache.catalina.core.ContainerBase.addChild(ContainerBase.java:875)
	at org.apache.catalina.core.StandardHost.addChild(StandardHost.java:652)
	at org.apache.catalina.startup.HostConfig.deployDirectory(HostConfig.java:1260)
	at org.apache.catalina.startup.HostConfig$DeployDirectory.run(HostConfig.java:2002)
	at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:471)
	at java.util.concurrent.FutureTask.run(FutureTask.java:262)
	at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1145)
	at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:615)
	at java.lang.Thread.run(Thread.java:745)
Caused by: java.lang.IllegalArgumentException: Could not resolve placeholder 'driverClassName' in string value "${driverClassName}"
	at org.springframework.util.PropertyPlaceholderHelper.parseStringValue(PropertyPlaceholderHelper.java:174)
	at org.springframework.util.PropertyPlaceholderHelper.replacePlaceholders(PropertyPlaceholderHelper.java:126)
	at org.springframework.beans.factory.config.PropertyPlaceholderConfigurer$PlaceholderResolvingStringValueResolver.resolveStringValue(PropertyPlaceholderConfigurer.java:258)
	at org.springframework.beans.factory.config.BeanDefinitionVisitor.resolveStringValue(BeanDefinitionVisitor.java:282)
	at org.springframework.beans.factory.config.BeanDefinitionVisitor.resolveValue(BeanDefinitionVisitor.java:204)
	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)
	... 22 more

2、错误原因

     由于在ApplicationContext.xml文件里获取MySQL连接配置，dataSource里有属性

<property name="driverClassName" value="${driverClassName}" />  

      但是在mysql.properties中没有配置这个属性

3、解决办法

     在mysql.properties属性文件中添加一行

driverClassName=com.mysql.jdbc.Driver