1.WebMvcAutoConfiguration

EnableWebMvcConfiguration自动装配类负责加载SpringMVC涉及的HandlerAdapter、HandlerMapping、ExceptionHandlerExceptionResolver等。
SpringMVC利用 DispatchServlet 处理上游Tomcat的请求时，会被HandlerMapping、HandlerAdapter的相关子类分别先后执行，这样做的原因是：

1. 通过RequestUril找到相应的handler是因为HandlerMapping提前建立了 RequestUril & Handler 之间的映射关系。
2. 不同HandlerMapping表明解析Handler上的Uri方式是不同的。
3. HandlerAdapter触发执行 Uri 在Handler中的目标方法。

WebMvcAutoConfigurationAdapter自动装配类负责加载SpringMVC涉及的静态资源等Web资源。例如LocaleResolver、视图解析器InternalResourceViewResolver、ContentNegotiatingViewResolver等。

@Configuration(proxyBeanMethods = false)
public class WebMvcAutoConfiguration {
   

	private static final String[] SERVLET_LOCATIONS = {
    "/" };

	@Configuration(proxyBeanMethods = false)
	@Import(EnableWebMvcConfiguration.class)
	@EnableConfigurationProperties({
    WebMvcProperties.class, ResourceProperties.class })
	@Order(0)
	public static class WebMvcAutoConfigurationAdapter implements WebMvcConfigurer {
   
		...
		@Bean
		@ConditionalOnBean(ViewResolver.class)
		@ConditionalOnMissingBean(name = "viewResolver", value = ContentNegotiatingViewResolver.class)
		public ContentNegotiatingViewResolver viewResolver(BeanFactory beanFactory) {
   ...}
		...
	}
	// 该注解保证父类WebMvcConfigurationSupport也参与SpringBoot启动过程中各个注解的解析过程
	@Configuration(proxyBeanMethods = false)
	public static class EnableWebMvcConfiguration extends DelegatingWebMvcConfiguration {
   
		...
		@Bean
		@Override
		public RequestMappingHandlerAdapter requestMappingHandlerAdapter(
				@Qualifier("mvcContentNegotiationManager") ContentNegotiationManager m,
				@Qualifier("mvcConversionService") FormattingConversionService c,
				@Qualifier("mvcValidator") Validator v) {
   
			RequestMappingHandlerAdapter adapter = super.requestMappingHandlerAdapter(m,c, v);
			boolean ignoreDefaultModelOnRedirect = this.mvcProperties.isIgnoreDefaultModelOnRedirect();
			adapter.setIgnoreDefaultModelOnRedirect(this.mvcProperties == null || ignoreDefaultModelOnRedirect);
			return adapter;
		}
		...
		@Bean
		@Primary
		@Override
		public RequestMappingHandlerMapping requestMappingHandlerMapping(
				@Qualifier("mvcContentNegotiationManager") ContentNegotiationManager manager,
				@Qualifier("mvcConversionService") FormattingConversionService conversionService,
				@Qualifier("mvcResourceUrlProvider") ResourceUrlProvider resourceUrlProvider) {
   
			// 调用父类WebMvcConfigurationSupport
			return super.requestMappingHandlerMapping(manager, conversionService,resourceUrlProvider);
		}
		...
	}
}

1.2.WebMvcConfigurationSupport

public class WebMvcConfigurationSupport implements ApplicationContextAware, ServletContextAware {
   
	@Bean
	public RequestMappingHandlerMapping requestMappingHandlerMapping(...}
	
	@Bean
	public PathMatcher mvcPathMatcher() {
   ...}
	
	@Bean
	public BeanNameUrlHandlerMapping beanNameHandlerMapping(...}
	
	@Bean
	public HandlerExceptionResolver handlerExceptionResolver(
			@Qualifier("mvcContentNegotiationManager") ContentNegotiationManager contentNegotiationManager) {
   
		List<HandlerExceptionResolver> exceptionResolvers = new ArrayList<>();
		configureHandlerExceptionResolvers(exceptionResolvers);
		if (exceptionResolvers.isEmpty()) {
   
			addDefaultHandlerExceptionResolvers(exceptionResolvers, contentNegotiationManager);
		}