springBoot是如何自动处理静态并映射静态资源的，直接上代码。

一、在springBoot  autoconfigure jar包中，存在WebMvcAutoConfiguration 自动配置类，该类的生效条件是：存在Servlet  ,DispatcheServlet  ,WebMvcConfigurer这三个类，

@ConditionalOnClass({ Servlet.class, DispatcherServlet.class, WebMvcConfigurer.class })

以及不存在：自定义的WebMvc配置类

@ConditionalOnMissingBean(WebMvcConfigurationSupport.class)

二、找到内部类：该内部类任然是一个配置类，由注解：@Configuration标识

public static class WebMvcAutoConfigurationAdapter implements WebMvcConfigurer, ServletContextAware

该自动配置类提供了一个有参构造器：参数从spring容器中获取。

①：ObjectProvider<HttpMessageConverters> messageConvertersProvider ：消息转换器

②：WebProperties webProperties：配置属性

③：ListableBeanFactory beanFactory：IOC容器

④：ObjectProvider<ResourceHandlerRegistrationCustomizer> resourceHandlerRegistrationCustomizerProvider：资源处理自定义器

⑤：ObjectProvider<DispatcherServletPath> dispatcherServletPath：处理的路径

⑥：ObjectProvider<ServletRegistrationBean<?>> servletRegistrations：注册原生的Servlet组件例如：Servlet/Listener/Filter等，通过注解：@WebServlet  @WebFilter @WebListener

		public WebMvcAutoConfigurationAdapter(WebProperties webProperties, WebMvcProperties mvcProperties,
				ListableBeanFactory beanFactory, ObjectProvider<HttpMessageConverters> messageConvertersProvider,
				ObjectProvider<ResourceHandlerRegistrationCustomizer> resourceHandlerRegistrationCustomizerProvider,
				ObjectProvider<DispatcherServletPath> dispatcherServletPath,
				ObjectProvider<ServletRegistrationBean<?>> servletRegistrations) {
			this.resourceProperties = webProperties.getResources();
			this.mvcProperties = mvcProperties;
			this.beanFactory = beanFactory;
			this.messageConvertersProvider = messageConvertersProvider;
			this.resourceHandlerRegistrationCustomizer = resourceHandlerRegistrationCustomizerProvider.getIfAvailable();
			this.dispatcherServletPath = dispatcherServletPath;
			this.servletRegistrations = servletRegistrations;
			this.mvcProperties.checkConfiguration();
		}

配置消息转换器：

		@Override
		public void configureMessageConverters(List<HttpMessageConverter<?>> converters) {
			this.messageConvertersProvider
					.ifAvailable((customConverters) -> converters.addAll(customConverters.getConverters()));
		}

配置视图解析器：

		@Bean
		@ConditionalOnMissingBean
		public InternalResourceViewResolver defaultViewResolver() {
			InternalResourceViewResolver resolver = new InternalResourceViewResolver();
			resolver.setPrefix(this.mvcProperties.getView().getPrefix());
			resolver.setSuffix(this.mvcProperties.getView().getSuffix());
			return resolver;
		}

配置资源处理器：

通过：

#禁用静态资源规则
spring:
  web:
    resources:
      add-mappings: true

		@Override
		public void addResourceHandlers(ResourceHandlerRegistry registry) {
            //禁用静态资源，则后面的代码全部不生效
			if (!this.resourceProperties.isAddMappings()) {
				logger.debug("Default resource handling disabled");
				return;
			}
            //处理webjars请求路径映射
			addResourceHandler(registry, "/webjars/**", "classpath:/META-INF/resources/webjars/");
            //private String staticPathPattern = "/**";  /**请求由下面代码处理
			addResourceHandler(registry, this.mvcProperties.getStaticPathPattern(), (registration) -> {
				registration.addResourceLocations(this.resourceProperties.getStaticLocations());
				if (this.servletContext != null) {
					ServletContextResource resource = new ServletContextResource(this.servletContext, SERVLET_LOCATION);
					registration.addResourceLocations(resource);
				}
			});
		}

//获取静态资源位置
this.resourceProperties.getStaticLocations()

该类通过：@EnableConfigurationProperties  绑定配置类：WebMvcProperties.class, WebProperties.class，实现自动配置。

@EnableConfigurationProperties({ WebMvcProperties.class, WebProperties.class })

三、进入WebProperties  配置类中，该类通过配置文件注@ConfigurationProperties("spring.web")

找到配置文件中以：spring.web开头的配置，作为用户自定义配置属性。

 

 四：欢迎页配置：WelcomePageHandlerMapping

		@Bean
		public WelcomePageHandlerMapping welcomePageHandlerMapping(ApplicationContext applicationContext,
				FormattingConversionService mvcConversionService, ResourceUrlProvider mvcResourceUrlProvider) {
			WelcomePageHandlerMapping welcomePageHandlerMapping = new WelcomePageHandlerMapping(
					new TemplateAvailabilityProviders(applicationContext), applicationContext, getWelcomePage(),
					this.mvcProperties.getStaticPathPattern());
			welcomePageHandlerMapping.setInterceptors(getInterceptors(mvcConversionService, mvcResourceUrlProvider));
			welcomePageHandlerMapping.setCorsConfigurations(getCorsConfigurations());
			return welcomePageHandlerMapping;
		}