springMVC applicationContext.xml

        最近做一个判断用户是否处于会话状态的filter，在filter中需要调用servicebean，结果是无法注入servicebean，因为web加载方式listener>filter>servlet，所以在在filter初始化时bean还未初始化。

       最后想通过这个方法获取bean

ApplicationContext ac = WebApplicationContextUtils.getWebApplicationContext(session.getServletContext());
serviceBus servicebus = (serviceBus) ac.getBean("servicebus");

使用applicationContext 就必须使用spring的ContextLoaderListener 加载applicationContext.xml配置

 <listener>
  <listener-class> org.springframework.web.context.ContextLoaderListener</listener-class>
  </listener>

    通过实践发现，web在启动时，首先是加载applicationContext.xml,而通过ApplicationContext 获取bean，只能在applicationContext中获取，而不能在springmvc-servlet.xml中获取。

    最后将注解扫描配置从springmvc-servlet.xml中移至到applicationContext.xml中，filter中成功获取bean。

   如果注解扫描配置在springmvc-servlet.xml则在

ac.getBean("servicebus");时发现一下错误，

所以

<pre name="code" class="java">WebApplicationContextUtils.getWebApplicationContext(session.getServletContext());<span style="background-color: rgb(240, 240, 240);">获取的是父容器applicationContext 而不能获取到springservlet容器的bean</span>

五月 17, 2016 3:56:24 下午 org.apache.catalina.core.StandardWrapperValve invoke
SEVERE: Servlet.service() for servlet [jsp] in context with path [/portal] threw exception
org.springframework.beans.factory.NoSuchBeanDefinitionException: No bean named 'servicebus' is defined
	at org.springframework.beans.factory.support.DefaultListableBeanFactory.getBeanDefinition(DefaultListableBeanFactory.java:694)
	at org.springframework.beans.factory.support.AbstractBeanFactory.getMergedLocalBeanDefinition(AbstractBeanFactory.java:1168)
	at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:281)
	at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:194)
	at org.springframework.context.support.AbstractApplicationContext.getBean(AbstractApplicationContext.java:956)
	at filter.session.doFilter(session.java:53)
	at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:243)
	at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:210)
	at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:222)
	at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:123)
	at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:472)
	at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:171)
	at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:99)
	at org.apache.catalina.valves.AccessLogValve.invoke(AccessLogValve.java:947)
	at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:118)
	at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:408)
	at org.apache.coyote.http11.AbstractHttp11Processor.process(AbstractHttp11Processor.java:1009)
	at org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:589)
	at org.apache.tomcat.util.net.JIoEndpoint$SocketProcessor.run(JIoEndpoint.java:312)
	at java.util.concurrent.ThreadPoolExecutor.runWorker(Unknown Source)
	at java.util.concurrent.ThreadPoolExecutor$Worker.run(Unknown Source)
	at java.lang.Thread.run(Unknown Source)

资料：

applicationContext是mvc context的父容器，mvc context可以引用applicationContext的bean，而applicationContext无法引用到mvc的bean

spring查找bean，会现在当前context中查找，如果没有满足的，再到父容器查找

两个不同的spring context，是不会有冲突的，是可以存在相同的bean定义的，只不过优先查找当前context