SpringBoot源码学习系列之SpringMVC自动配置

    - [1、ContentNegotiatingViewResolver](https://cloud.tencent.com/developer/audit/support-plan/6805681#1ContentNegotiatingViewResolver_36)
    - [2、静态资源](https://cloud.tencent.com/developer/audit/support-plan/6805681#2_84)
    - [3、自动注册 Converter, GenericConverter, and Formatter beans.](https://cloud.tencent.com/developer/audit/support-plan/6805681#3_Converter_GenericConverter_and_Formatter_beans_132)
    - [4、支持HttpMessageConverters](https://cloud.tencent.com/developer/audit/support-plan/6805681#4HttpMessageConverters_161)
    - [5、支持MessageCodesResolver](https://cloud.tencent.com/developer/audit/support-plan/6805681#5MessageCodesResolver_170)
    - [6、首页支持](https://cloud.tencent.com/developer/audit/support-plan/6805681#6_180)
    - [7、网站logo设置](https://cloud.tencent.com/developer/audit/support-plan/6805681#7logo_187)
    - [8、ConfigurableWebBindingInitializer 初始绑定器](https://cloud.tencent.com/developer/audit/support-plan/6805681#8ConfigurableWebBindingInitializer__191)

@Configuration(proxyBeanMethods = false)//指定WebMvcAutoConfiguration不代理方法
@ConditionalOnWebApplication(type = Type.SERVLET)//在web环境(selvlet)才会起效
@ConditionalOnClass({ Servlet.class, DispatcherServlet.class, WebMvcConfigurer.class })//系统有有Servlet，DispatcherServlet(Spring核心的分发器)，WebMvcConfigurer的情况，这个自动配置类才起效
@ConditionalOnMissingBean(WebMvcConfigurationSupport.class)//系统没有WebMvcConfigurationSupport这个类的情况，自动配置起效
@AutoConfigureOrder(Ordered.HIGHEST_PRECEDENCE + 10)
@AutoConfigureAfter({ DispatcherServletAutoConfiguration.class, TaskExecutionAutoConfiguration.class,
		ValidationAutoConfiguration.class })
public class WebMvcAutoConfiguration {
....
}

@Configuration(proxyBeanMethods = false)//定义为配置类
	@Import(EnableWebMvcConfiguration.class)//spring底层注解,将EnableWebMvcConfiguration加到容器
	@EnableConfigurationProperties({ WebMvcProperties.class, ResourceProperties.class })//使WebMvcProperties、ResourceProperties配置类生效
	@Order(0)
	public static class WebMvcAutoConfigurationAdapter implements WebMvcConfigurer {
	....
}

@Override
	protected void initServletContext(ServletContext servletContext) {
	//调用Spring的BeanFactoryUtils扫描容器里的所有视图解析器ViewResolver类
		Collection<ViewResolver> matchingBeans =
				BeanFactoryUtils.beansOfTypeIncludingAncestors(obtainApplicationContext(), ViewResolver.class).values();
		if (this.viewResolvers == null) {
			this.viewResolvers = new ArrayList<>(matchingBeans.size());
			//遍历候选的viewResolvers，封装到this.viewResolvers列表
			for (ViewResolver viewResolver : matchingBeans) {
				if (this != viewResolver) {
					this.viewResolvers.add(viewResolver);
				}
			}
		}
		else {
			for (int i = 0; i < this.viewResolvers.size(); i++) {
				ViewResolver vr = this.viewResolvers.get(i);
				if (matchingBeans.contains(vr)) {
					continue;
				}
				String name = vr.getClass().getName() + i;
				obtainApplicationContext().getAutowireCapableBeanFactory().initializeBean(vr, name);
			}

		}
		AnnotationAwareOrderComparator.sort(this.viewResolvers);
		this.cnmFactoryBean.setServletContext(servletContext);
	}

@Override
		public void addResourceHandlers(ResourceHandlerRegistry registry) {
			if (!this.resourceProperties.isAddMappings()) {
				logger.debug("Default resource handling disabled");
				return;
			}
			Duration cachePeriod = this.resourceProperties.getCache().getPeriod();
			//CacheControl是Spring框架提供的http缓存
			CacheControl cacheControl = this.resourceProperties.getCache().getCachecontrol().toHttpCacheControl();
			//读取到webjars资源，将classpath:/META-INF/resources/webjars/的webjars资源都扫描出来
			if (!registry.hasMappingForPattern("/webjars/**")) {
				customizeResourceHandlerRegistration(registry.addResourceHandler("/webjars/**")
						.addResourceLocations("classpath:/META-INF/resources/webjars/")
						.setCachePeriod(getSeconds(cachePeriod)).setCacheControl(cacheControl));
			}
			String staticPathPattern = this.mvcProperties.getStaticPathPattern();
			if (!registry.hasMappingForPattern(staticPathPattern)) {
				customizeResourceHandlerRegistration(registry.addResourceHandler(staticPathPattern)
						.addResourceLocations(getResourceLocations(this.resourceProperties.getStaticLocations()))
						.setCachePeriod(getSeconds(cachePeriod)).setCacheControl(cacheControl));
			}
		}

@Bean
		@ConditionalOnMissingBean//没有自定义localeResolver的情况
		@ConditionalOnProperty(prefix = "spring.mvc", name = "locale")//application.properties有配置了spring.mvc.locale
		public LocaleResolver localeResolver() {
			if (this.mvcProperties.getLocaleResolver() == WebMvcProperties.LocaleResolver.FIXED) {
				return new FixedLocaleResolver(this.mvcProperties.getLocale());
			}
			//默认使用AcceptHeaderLocaleResolver 
			AcceptHeaderLocaleResolver localeResolver = new AcceptHeaderLocaleResolver();
			localeResolver.setDefaultLocale(this.mvcProperties.getLocale());
			return localeResolver;
		}