Line 8 in XML document from class path resource [conf/applicationContext.xml] is invalid

@[TOC**] 错误：Line 8 in XML document from class path resource [conf/applicationContext.xml] is invalid(这里写自定义目录标题)**

在进行SSM框架整合时，出现以下问题：
org.springframework.beans.factory.xml.XmlBeanDefinitionStoreException: Line 9 in XML document from class path resource [conf/applicationContext.xml] is invalid; nested exception is org.xml.sax.SAXParseException; lineNumber: 9; columnNumber: 78; cvc-complex-type.2.4.c: 閫氶厤绗︾殑鍖归厤寰堝叏闈�, 浣嗘棤娉曟壘鍒板厓绱� ‘context:property-placeholder’ 鐨勫０鏄庛��
at org.springframework.beans.factory.xml.XmlBeanDefinitionReader.doLoadBeanDefinitions(XmlBeanDefinitionReader.java:400)
at org.springframework.beans.factory.xml.XmlBeanDefinitionReader.loadBeanDefinitions(XmlBeanDefinitionReader.java:336)
at org.springframework.beans.factory.xml.XmlBeanDefinitionReader.loadBeanDefinitions(XmlBeanDefinitionReader.java:305)
at org.springframework.beans.factory.support.AbstractBeanDefinitionReader.loadBeanDefinitions(AbstractBeanDefinitionReader.java:188)
at org.springframework.beans.factory.support.AbstractBeanDefinitionReader.loadBeanDefinitions(AbstractBeanDefinitionReader.java:224)
at org.springframework.beans.factory.support.AbstractBeanDefinitionReader.loadBeanDefinitions(AbstractBeanDefinitionReader.java:195)
at org.springframework.web.context.support.XmlWebApplicationContext.loadBeanDefinitions(XmlWebApplicationContext.java:125)
at org.springframework.web.context.support.XmlWebApplicationContext.loadBeanDefinitions(XmlWebApplicationContext.java:94)
at org.springframework.context.support.AbstractRefreshableApplicationContext.refreshBeanFactory(AbstractRefreshableApplicationContext.java:133)
at org.springframework.context.support.AbstractApplicationContext.obtainFreshBeanFactory(AbstractApplicationContext.java:637)
at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:522)

导致tomcat启动失败，其中我的applicationContext.xml文件编写如下：

要在上述的applicationContext.xml文件中加入一行代码如下：
http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context-3.0.xsd

这样一来，Tomcat启动成功。