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Spring父容器与子容器
在使用spring+springMVC的web工程中，我们一般会在web.xml中做如下配置：
<context-param> <param-name>contextConfigLocation</param-name> <param-value>classpath:application.xml</param-value> </context-param> <!-- spring context listener --> <listener> <listener-class>org.springframework.web.context.ContextLoaderListener</listener-class> </listener> <!-- spring mvc dispatcher servlet --> <servlet> <servlet-name>spring</servlet-name> <servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class> <init-param> <param-name>contextConfigLocation</param-name> <param-value>classpath:spring-servlet.xml</param-value> </init-param> <load-on-startup>1</load-on-startup> </servlet> <servlet-mapping> <servlet-name>spring</servlet-name> <url-pattern>/</url-pattern> </servlet-mapping>
这样就会产生两个spring容器，一个父容器，一个子容器。
父容器Root WebApplicationContext由ContextLoaderListener加载
子容器WebApplicationContext for namespace ‘spring-servlet‘由DispatcherServlet加载（‘spring-servlet‘子容器的contextConfigLocation，web.xml中配置的）
从容器里面getBean的时候，先从本容器取，如果取不到再从父容器取
原码跟踪得到如下结果：
ContextLoaderListener:
beanFactory : org.springframework.beans.factory.support.DefaultListableBeanFactory@501af69e: defining beans [commonService,org.springframework.context.annotation.internalConfigurationAnnotationProcessor,org.springframework.context.annotation.internalAutowiredAnnotationProcessor,org.springframework.context.annotation.internalRequiredAnnotationProcessor,org.springframework.context.annotation.internalCommonAnnotationProcessor,propertyConfigurer,messageSource,exceptionHandler,compositeFilter,dataSource,sqlSessionFactory,transactionManager,org.springframework.aop.config.internalAutoProxyCreator,org.springframework.transaction.annotation.AnnotationTransactionAttributeSource#0,org.springframework.transaction.interceptor.TransactionInterceptor#0,org.springframework.transaction.config.internalTransactionAdvisor,org.mybatis.spring.mapper.MapperScannerConfigurer#0,tokenClient,formTokenManager,formTokenAspect,formTokenPointCut,org.springframework.aop.aspectj.AspectJPointcutAdvisor#0,responseAspect,responsePointCut,org.springframework.aop.aspectj.AspectJPointcutAdvisor#1,multiViewResolver,excelView]; root of factory hierarchy
applicationContext:（对象地址：6be04fe1，父容器：null）
(org.springframework.web.context.support.XmlWebApplicationContext@6be04fe1) Root WebApplicationContext: startup date [Thu Feb 16 09:42:54 CST 2017]; root of context hierarchy
contextId : org.springframework.web.context.WebApplicationContext:
beanFactory.registerResolvableDependency(ApplicationContext.class, this);将父容器（根容器）注册到父容器的beanFactory中
DispatcherServlet:
ServletContext : org.apache.catalina.core.ApplicationContextFacade@78d9af50
applicationContext : （ 对象地址：8323ee8，父容器：ContextLoaderListener加载的 applicationContext，即 Root WebApplicationContext）
(org.springframework.web.context.support.XmlWebApplicationContext@8323ee8) WebApplicationContext for namespace ‘spring-servlet‘: startup date [Thu Jan 01 08:00:00 CST 1970]; parent: Root WebApplicationContext
contextId : org.springframework.web.context.WebApplicationContext:/spring
beanFactory.registerResolvableDependency(ApplicationContext.class, this); 将子容器注册到子容器的beanFactory中
父容器的ListableBeanFactory中注册的bean：（由ContextLoadListener初始化的容器）
(java.lang.String[]) [commonServiceinitServicepageServiceorg.springframework.context.annotation.internalConfigurationAnnotationProcessororg.springframework.context.annotation.internalAutowiredAnnotationProcessororg.springframework.context.annotation.internalRequiredAnnotationProcessororg.springframework.context.annotation.internalCommonAnnotationProcessorpropertyConfigurermessageSourceexceptionHandlercompositeFilterdataSourcesqlSessionFactorytransactionManagerorg.springframework.aop.config.internalAutoProxyCreatororg.springframework.transaction.annotation.AnnotationTransactionAttributeSource#0org.springframework.transaction.interceptor.TransactionInterceptor#0org.springframework.transaction.config.internalTransactionAdvisororg.mybatis.spring.mapper.MapperScannerConfigurer#0tokenClientformTokenManagerformTokenAspectformTokenPointCutorg.springframework.aop.aspectj.AspectJPointcutAdvisor#0responseAspectresponsePointCutorg.springframework.aop.aspectj.AspectJPointcutAdvisor#1multiViewResolverexcelVieworg.springframework.context.annotation.ConfigurationClassPostProcessor.importAwareProcessororg.springframework.context.annotation.ConfigurationClassPostProcessor.enhancedConfigurationProcessorICommonDaoIPageDao]
子容器的ListableBeanFactory中注册的bean：（由DispatcherServlet初始化的容器）
(java.lang.String[]) [baseTestControllercaptchaControllererrorPageTestControllerexcelExportControllerexceptionHandlerTestControllerparamProcessControllertokenTestControllervalidatorTestControllerorg.springframework.context.annotation.internalConfigurationAnnotationProcessororg.springframework.context.annotation.internalAutowiredAnnotationProcessororg.springframework.context.annotation.internalRequiredAnnotationProcessororg.springframework.context.annotation.internalCommonAnnotationProcessororg.springframework.aop.config.internalAutoProxyCreatormvcContentNegotiationManagerorg.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerMapping#0org.springframework.format.support.FormattingConversionServiceFactoryBean#0org.springframework.validation.beanvalidation.OptionalValidatorFactoryBean#0org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter#0mvcUriComponentsContributororg.springframework.web.servlet.handler.MappedInterceptor#0org.springframework.web.servlet.mvc.method.annotation.ExceptionHandlerExceptionResolver#0org.springframework.web.servlet.mvc.annotation.ResponseStatusExceptionResolver#0org.springframework.web.servlet.mvc.support.DefaultHandlerExceptionResolver#0org.springframework.web.servlet.handler.BeanNameUrlHandlerMappingorg.springframework.web.servlet.mvc.HttpRequestHandlerAdapterorg.springframework.web.servlet.mvc.SimpleControllerHandlerAdapterorg.springframework.web.servlet.resource.DefaultServletHttpRequestHandler#0org.springframework.web.servlet.handler.SimpleUrlHandlerMapping#0org.springframework.web.servlet.view.InternalResourceViewResolver#0]
Spring父容器与子容器