20、SpringBoot 源码分析 - DispatcherServlet初始化二

基本流程图,方便查看

 

initThemeResolver

这个跟前面讲initLocaleResolver一样,最后获取默认的。

initHandlerMappings

这个获取处理器映射器就不一样啦,因为可能有多个,首先去容器里取HandlerMapping类型的多个实例,这个是取的到的,因为自动配置中配置了一些,如果没取到才会去找默认的:


public static final String HANDLER_MAPPING_BEAN_NAME = "handlerMapping";

private void initHandlerMappings(ApplicationContext context) {
   
     
		this.handlerMappings = null;

		if (this.detectAllHandlerMappings) {
   
     //可以找多个
			// Find all HandlerMappings in the ApplicationContext, including ancestor contexts.
			Map<String, HandlerMapping> matchingBeans =
					BeanFactoryUtils.beansOfTypeIncludingAncestors(context, HandlerMapping.class, true, false);
			if (!matchingBeans.isEmpty()) {
   
     
				this.handlerMappings = new ArrayList<>(matchingBeans.values());
				// We keep HandlerMappings in sorted order.
				AnnotationAwareOrderComparator.sort(this.handlerMappings);
			}
		}
		else {
   
     //只能找一个
			try {
   
     
				HandlerMapping hm = context.getBean(HANDLER_MAPPING_BEAN_NAME, HandlerMapping.class);
				this.handlerMappings = Collections.singletonList(hm);
			}
			catch (NoSuchBeanDefinitionException ex) {
   
     
				// Ignore, we'll add a default HandlerMapping later.
			}
		}

		// Ensure we have at least one HandlerMapping, by registering
		// a default HandlerMapping if no other mappings are found.
		if (this.handlerMappings == null) {
   
     
			this.handlerMappings = getDefaultStrategies(context, HandlerMapping.class);
			if (logger.isTraceEnabled()) {
   
     
				logger.trace("No HandlerMappings declared for servlet '" + getServletName() +
						"': using default strategies from DispatcherServlet.properties");
			}
		}
	}

最后拿到了5个:
 

都是哪来的

我们看看这些是怎么来的,其实都是自动配置里的EnableWebMvcConfiguration中的。
WebMvcAutoConfigurationEnableWebMvcConfigurationRequestMappingHandlerMapping
 
WebMvcAutoConfigurationEnableWebMvcConfigurationWelcomePageHandlerMapping
 
WebMvcAutoConfigurationEnableWebMvcConfiguration的父类WebMvcConfigurationSupportBeanNameUrlHandlerMapping
 
WebMvcAutoConfigurationEnableWebMvcConfiguration的父类WebMvcConfigurationSupportRouterFunctionMapping
 
WebMvcAutoConfigurationEnableWebMvcConfiguration的父类WebMvcConfigurationSupportSimpleUrlHandlerMapping
 

好了,今天就到这里了,希望对学习理解有帮助,大神看见勿喷,仅为自己的学习理解,能力有限,请多包涵。