14:56:42,261 INFO ContextLoader:272 - Root WebApplicationContext: initialization started
14:56:42,343 DEBUG StandardServletEnvironment:100 - Initializing new StandardServletEnvironment
14:56:42,365 INFO XmlWebApplicationContext:495 - Refreshing Root WebApplicationContext: startup date [Mon Feb 06 14:56:42 CST 2012]; root of context hierarchy
14:56:42,441 DEBUG PathMatchingResourcePatternResolver:550 - Looking for matching resources in directory tree [D:\Work\Demo2do\Sample\target\classes\context]
14:56:42,442 DEBUG PathMatchingResourcePatternResolver:612 - Searching directory [D:\Work\Demo2do\Sample\target\classes\context] for files matching pattern [D:/Work/Demo2do/Sample/target/classes/context/applicationContext-*.xml]
14:56:42,446 DEBUG PathMatchingResourcePatternResolver:351 - Resolved location pattern [classpath:context/applicationContext-*.xml] to resources [file [D:\Work\Demo2do\Sample\target\classes\context\applicationContext-configuration.xml]]
14:56:42,447 INFO XmlBeanDefinitionReader:315 - Loading XML bean definitions from file [D:\Work\Demo2do\Sample\target\classes\context\applicationContext-configuration.xml]
14:56:42,486 DEBUG PluggableSchemaResolver:140 - Loading schema mappings from [META-INF/spring.schemas]
14:56:42,597 DEBUG DefaultBeanDefinitionDocumentReader:108 - Loading bean definitions
14:56:42,658 DEBUG PathMatchingResourcePatternResolver:550 - Looking for matching resources in directory tree [D:\Work\Demo2do\Sample\target\classes\com\demo2do\sample]
14:56:42,699 DEBUG ClassPathBeanDefinitionScanner:243 - Identified candidate component class: file [D:\Work\Demo2do\Sample\target\classes\com\demo2do\sample\service\impl\BlogServiceImpl.class]
14:56:42,750 DEBUG XmlBeanDefinitionReader:216 - Loaded 5 bean definitions from location pattern [classpath:context/applicationContext-*.xml]
14:56:42,750 DEBUG XmlWebApplicationContext:525 - Bean factory for Root WebApplicationContext: org.springframework.beans.factory.support.DefaultListableBeanFactory@478e4327: defining beans [blogService,org.springframework.context.annotation.internalConfigurationAnnotationProcessor,org.springframework.context.annotation.internalAutowiredAnnotationProcessor,org.springframework.context.annotation.internalRequiredAnnotationProcessor,org.springframework.context.annotation.internalCommonAnnotationProcessor]; root of factory hierarchy
14:56:42,860 DEBUG ContextLoader:296 - Published root WebApplicationContext as ServletContext attribute with name [org.springframework.web.context.WebApplicationContext.ROOT]
14:56:42,860 INFO ContextLoader:301 - Root WebApplicationContext: initialization completed in 596 ms
14:56:42,935 DEBUG DispatcherServlet:115 - Initializing servlet 'dispatcher'
14:56:42,974 INFO DispatcherServlet:444 - FrameworkServlet 'dispatcher': initialization started
14:56:42,974 DEBUG DispatcherServlet:572 - Servlet with name 'dispatcher' will try to create custom WebApplicationContext context of class 'org.springframework.web.context.support.XmlWebApplicationContext', using parent context [Root WebApplicationContext: startup date [Mon Feb 06 14:56:42 CST 2012]; root of context hierarchy]
14:56:42,979 INFO XmlWebApplicationContext:495 - Refreshing WebApplicationContext for namespace 'dispatcher-servlet': startup date [Mon Feb 06 14:56:42 CST 2012]; parent: Root WebApplicationContext
14:56:42,983 INFO XmlBeanDefinitionReader:315 - Loading XML bean definitions from class path resource [web/applicationContext-dispatcherServlet.xml]
14:56:42,987 DEBUG PluggableSchemaResolver:140 - Loading schema mappings from [META-INF/spring.schemas]
14:56:43,035 DEBUG DefaultBeanDefinitionDocumentReader:108 - Loading bean definitions
14:56:43,075 DEBUG PathMatchingResourcePatternResolver:550 - Looking for matching resources in directory tree [D:\Work\Demo2do\Sample\target\classes\com\demo2do\sample\web\controller]
14:56:43,075 DEBUG PathMatchingResourcePatternResolver:612 - Searching directory [D:\Work\Demo2do\Sample\target\classes\com\demo2do\sample\web\controller] for files matching pattern [D:/Work/Demo2do/Sample/target/classes/com/demo2do/sample/web/controller*.class]
14:56:43,077 DEBUG PathMatchingResourcePatternResolver:351 - Resolved location pattern [classpath*:com/demo2do/sample/web/controller*.class] to resources [file [D:\Work\Demo2do\Sample\target\classes\com\demo2do\sample\web\controller\BlogController.class], file [D:\Work\Demo2do\Sample\target\classes\com\demo2do\sample\web\controller\UserController.class]]
14:56:43,079 DEBUG ClassPathBeanDefinitionScanner:243 - Identified candidate component class: file [D:\Work\Demo2do\Sample\target\classes\com\demo2do\sample\web\controller\BlogController.class]
14:56:43,080 DEBUG ClassPathBeanDefinitionScanner:243 - Identified candidate component class: file [D:\Work\Demo2do\Sample\target\classes\com\demo2do\sample\web\controller\UserController.class]
14:56:43,089 DEBUG XmlBeanDefinitionReader:216 - Loaded 19 bean definitions from location pattern [classpath:web/applicationContext-dispatcherServlet.xml]
14:56:43,089 DEBUG XmlWebApplicationContext:525 - Bean factory for WebApplicationContext for namespace 'dispatcher-servlet': org.springframework.beans.factory.support.DefaultListableBeanFactory@5e6458a6: defining beans [org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerMapping#0,org.springframework.format.support.FormattingConversionServiceFactoryBean#0,org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter#0,org.springframework.web.servlet.handler.MappedInterceptor#0,org.springframework.web.servlet.mvc.method.annotation.ExceptionHandlerExceptionResolver#0,org.springframework.web.servlet.mvc.annotation.ResponseStatusExceptionResolver#0,org.springframework.web.servlet.mvc.support.DefaultHandlerExceptionResolver#0,org.springframework.web.servlet.handler.BeanNameUrlHandlerMapping,org.springframework.web.servlet.mvc.HttpRequestHandlerAdapter,org.springframework.web.servlet.mvc.SimpleControllerHandlerAdapter,blogController,userController,org.springframework.context.annotation.internalConfigurationAnnotationProcessor,org.springframework.context.annotation.internalAutowiredAnnotationProcessor,org.springframework.context.annotation.internalRequiredAnnotationProcessor,org.springframework.context.annotation.internalCommonAnnotationProcessor,org.springframework.web.servlet.resource.ResourceHttpRequestHandler#0,org.springframework.web.servlet.handler.SimpleUrlHandlerMapping#0,org.springframework.web.servlet.view.InternalResourceViewResolver#0]; parent: org.springframework.beans.factory.support.DefaultListableBeanFactory@478e4327
14:56:43,323 DEBUG RequestMappingHandlerMapping:98 - Looking for request mappings in application context: WebApplicationContext for namespace 'dispatcher-servlet': startup date [Mon Feb 06 14:56:42 CST 2012]; parent: Root WebApplicationContext
14:56:43,345 INFO RequestMappingHandlerMapping:188 - Mapped "{[/blog],methods=[],params=[],headers=[],consumes=[],produces=[],custom=[]}" onto public org.springframework.web.servlet.ModelAndView com.demo2do.sample.web.controller.BlogController.index()
14:56:43,346 INFO RequestMappingHandlerMapping:188 - Mapped "{[/login],methods=[],params=[],headers=[],consumes=[],produces=[],custom=[]}" onto public org.springframework.web.servlet.ModelAndView com.demo2do.sample.web.controller.UserController.login(java.lang.String,java.lang.String)
14:56:43,707 DEBUG BeanNameUrlHandlerMapping:71 - Looking for URL mappings in application context: WebApplicationContext for namespace 'dispatcher-servlet': startup date [Mon Feb 06 14:56:42 CST 2012]; parent: Root WebApplicationContext
14:56:43,828 INFO SimpleUrlHandlerMapping:314 - Mapped URL path [/static/**] onto handler 'org.springframework.web.servlet.resource.ResourceHttpRequestHandler#0'
14:56:43,883 DEBUG DispatcherServlet:523 - Published WebApplicationContext of servlet 'dispatcher' as ServletContext attribute with name [org.springframework.web.servlet.FrameworkServlet.CONTEXT.dispatcher]
14:56:43,883 INFO DispatcherServlet:463 - FrameworkServlet 'dispatcher': initialization completed in 909 ms
14:56:43,883 DEBUG DispatcherServlet:136 - Servlet 'dispatcher' configured successfully
2687 [main] INFO org.mortbay.log - Started SelectChannelConnector@0.0.0.0:8080
Jetty Server started, use 2901 ms

引用

14:56:42,979  INFO XmlWebApplicationContext:495 - Refreshing WebApplicationContext for namespace 'dispatcher-servlet': startup date [Mon Feb 06 14:56:42 CST 2012]; parent: Root WebApplicationContext

Java代码  

@Override
protected void onRefresh(ApplicationContext context) {
      initStrategies(context);
}
protected void initStrategies(ApplicationContext context) {
      initMultipartResolver(context);
      initLocaleResolver(context);
      initThemeResolver(context);
      initHandlerMappings(context);
      initHandlerAdapters(context);
      initHandlerExceptionResolvers(context);
      initRequestToViewNameTranslator(context);
      initViewResolvers(context);
      initFlashMapManager(context);
}

Java代码  

private void initMultipartResolver(ApplicationContext context) {
      try {
            this.multipartResolver = context.getBean(MULTIPART_RESOLVER_BEAN_NAME, MultipartResolver.class);
            if (logger.isDebugEnabled()) {
                  logger.debug("Using MultipartResolver [" + this.multipartResolver + "]");
            }
      } catch (NoSuchBeanDefinitionException ex) {
            // Default is no multipart resolver.
            this.multipartResolver = null;
            if (logger.isDebugEnabled()) {
                  logger.debug("Unable to locate MultipartResolver with name '" + MULTIPART_RESOLVER_BEAN_NAME +
                  "': no multipart request handling provided");
            }
      }
}

downpour 写道

结论 DispatcherServlet中对于组件的初始化过程实际上是应用程序在WebApplicationContext中选择和查找组件实现类的过程，也是指定组件在SpringMVC中的默认行为方式的过程。

Java代码  

private void initHandlerAdapters(ApplicationContext context) {
      this.handlerAdapters = null;
      if (this.detectAllHandlerAdapters) {
            // Find all HandlerAdapters in the ApplicationContext, including ancestor contexts.
            Map<String, HandlerAdapter> matchingBeans = BeanFactoryUtils.beansOfTypeIncludingAncestors(context, HandlerAdapter.class, true, false);
            if (!matchingBeans.isEmpty()) {
                  this.handlerAdapters = new ArrayList<HandlerAdapter>(matchingBeans.values());
                  // We keep HandlerAdapters in sorted order.
                  OrderComparator.sort(this.handlerAdapters);
            }
      }
      else {
            try {
                  HandlerAdapter ha = context.getBean(HANDLER_ADAPTER_BEAN_NAME, HandlerAdapter.class);
                  this.handlerAdapters = Collections.singletonList(ha);
            }
            catch (NoSuchBeanDefinitionException ex) {
                  // Ignore, we'll add a default HandlerAdapter later.
            }
      }
      // Ensure we have at least some HandlerAdapters, by registering
      // default HandlerAdapters if no other adapters are found.
      if (this.handlerAdapters == null) {
            this.handlerAdapters = getDefaultStrategies(context, HandlerAdapter.class);
            if (logger.isDebugEnabled()) {
                  logger.debug("No HandlerAdapters found in servlet '" + getServletName() + "': using default");
            }
      }
}

引用

# Default implementation classes for DispatcherServlet's strategy interfaces. 

结合刚才initHandlerMappings的源码，我们可以发现如果没有开启detectAllHandlerAdapters选项或者根据HANDLER_ADAPTER_BEAN_NAME的名称没有找到相应的组件实现类，就会使用DispatcherServlet.properties文件中对于HandlerMapping接口的实现来进行组件默认行为的初始化。 

由此可见，DispatcherServlet.properties中所指定的所有接口的实现方式在Spring的容器WebApplicationContext中总有相应的定义。这一点，我们在组件的讨论中还会详谈。 

这个部分我们的侧重点是图中DispatcherServlet与容器之间的关系。读者需要理解的是图中为什么会有两份组件定义，它们之间的区别在哪里，以及DispatcherServlet在容器中查找组件的三种策略。 

小结 

在本文中，我们对SpringMVC的核心类：DispatcherServlet进行了一番梳理。也对整个SpringMVC的两条主线之一的初始化主线做了详细的分析。 

对于DispatcherServlet而言，重要的其实并不是这个类中的代码和逻辑，而是应该掌握这个类在整个框架中的作用以及与SpringMVC中其他要素的关系。 

对于初始化主线而言，核心其实仅仅在于那张笔者为大家精心打造的图。读者只要掌握了这张图，相信对整个SpringMVC的初始化过程会有一个全新���认识。