报错：java.lang.IllegalStateException: Context namespace element 'component-scan' and its parser class.

今天在将一个SSM项目部署到linux服务器上时，启动tomcat时报错：

[QC] ERROR [localhost-startStop-1] org.springframework.web.context.ContextLoader.initWebApplicationContext(215) | Context initialization failedorg.springframework.beans.factory.BeanDefinitionStoreException: Unexpected exception parsing XML document from file [/usr/local/tomcat/apache-tomcat-7.0.52/webapps/smart/WEB-INF/classes/spring/applicationContext-service.xml]; nested exception is java.lang.IllegalStateException: Context namespace element 'component-scan' and its parser class [org.springframework.context.annotation.ComponentScanBeanDefinitionParser] are only available on JDK 1.5 and higher        at org.springframework.beans.factory.xml.XmlBeanDefinitionReader.doLoadBeanDefinitions(XmlBeanDefinitionReader.java:420)        at org.springframework.beans.factory.xml.XmlBeanDefinitionReader.loadBeanDefinitions(XmlBeanDefinitionReader.java:342)        at org.springframework.beans.factory.xml.XmlBeanDefinitionReader.loadBeanDefinitions(XmlBeanDefinitionReader.java:310)        at org.springframework.beans.factory.support.AbstractBeanDefinitionReader.loadBeanDefinitions(AbstractBeanDefinitionReader.java:143)        at org.springframework.beans.factory.support.AbstractBeanDefinitionReader.loadBeanDefinitions(AbstractBeanDefinitionReader.java:178)        at org.springframework.beans.factory.support.AbstractBeanDefinitionReader.loadBeanDefinitions(AbstractBeanDefinitionReader.java:149)        at org.springframework.web.context.support.XmlWebApplicationContext.loadBeanDefinitions(XmlWebApplicationContext.java:124)        at org.springframework.web.context.support.XmlWebApplicationContext.loadBeanDefinitions(XmlWebApplicationContext.java:92)        at org.springframework.context.support.AbstractRefreshableApplicationContext.refreshBeanFactory(AbstractRefreshableApplicationContext.java:123)        at org.springframework.context.support.AbstractApplicationContext.obtainFreshBeanFactory(AbstractApplicationContext.java:422)        at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:352)        at org.springframework.web.context.ContextLoader.createWebApplicationContext(ContextLoader.java:255)        at org.springframework.web.context.ContextLoader.initWebApplicationContext(ContextLoader.java:199)        at org.springframework.web.context.ContextLoaderListener.contextInitialized(ContextLoaderListener.java:45)        at org.apache.catalina.core.StandardContext.listenerStart(StandardContext.java:4973)        at org.apache.catalina.core.StandardContext.startInternal(StandardContext.java:5467)        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:632)        at org.apache.catalina.startup.HostConfig.deployWAR(HostConfig.java:1073)        at org.apache.catalina.startup.HostConfig$DeployWar.run(HostConfig.java:1857)        at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:511)        at java.util.concurrent.FutureTask.run(FutureTask.java:266)        at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149)        at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624)        at java.lang.Thread.run(Thread.java:748)Caused by: java.lang.IllegalStateException: Context namespace element 'component-scan' and its parser class [org.springframework.context.annotation.ComponentScanBeanDefinitionParser] are only available on JDK 1.5 and higher        at org.springframework.context.config.ContextNamespaceHandler$1.parse(ContextNamespaceHandler.java:65)        at org.springframework.beans.factory.xml.NamespaceHandlerSupport.parse(NamespaceHandlerSupport.java:69)        at org.springframework.beans.factory.xml.BeanDefinitionParserDelegate.parseCustomElement(BeanDefinitionParserDelegate.java:1297)        at org.springframework.beans.factory.xml.BeanDefinitionParserDelegate.parseCustomElement(BeanDefinitionParserDelegate.java:1287)        at org.springframework.beans.factory.xml.DefaultBeanDefinitionDocumentReader.parseBeanDefinitions(DefaultBeanDefinitionDocumentReader.java:135)        at org.springframework.beans.factory.xml.DefaultBeanDefinitionDocumentReader.registerBeanDefinitions(DefaultBeanDefinitionDocumentReader.java:92)        at org.springframework.beans.factory.xml.XmlBeanDefinitionReader.registerBeanDefinitions(XmlBeanDefinitionReader.java:507)        at org.springframework.beans.factory.xml.XmlBeanDefinitionReader.doLoadBeanDefinitions(XmlBeanDefinitionReader.java:398)        ... 26 more

在百度之后，说是Spring包版本冲突了，但是这个项目使用的Maven进行管理，依赖中都是4.x版本的Spring，于是使用IDEA查看依赖关系图：

发现Dubbo依赖了一个Spring，并且版本是2.x的，于是排除这个依赖。

排除dubbo依赖的Spring：

重新部署项目，成功部署。

补充：百度上也有说将jdk8换成jdk7的，但是我试了试，并没有什么用，所以还是将低版本的Spring包排除最好。