【源码分析】SpringBoot 如何访问工程目录下的静态资源？ ​

By default, resources are mapped on /**, but you can tune that with the spring.mvc.static-path-pattern property. For instance, relocating all resources to /resources/** can be achieved as follows:

PropertiesYaml
spring.mvc.static-path-pattern=/resources/**

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spring.mvc.static-path-pattern=/res/**

7.1.6. Welcome Page
Spring Boot supports both static and templated welcome pages. It first looks for an index.html file in the configured static content locations. If one is not found, it then looks for an index template. If either is found, it is automatically used as the welcome page of the application.

/spring-boot-autoconfigure-2.5.1.jar!/org/springframework/boot/autoconfigure/web/servlet/WebMvcAutoConfiguration.class

@Override
        public void addResourceHandlers(ResourceHandlerRegistry registry) {
            // 相当于一个开关去控制静态资源处理器的加载，默认为true，设置为false就会禁止所有规则
            if (!this.resourceProperties.isAddMappings()) {
                logger.debug("Default resource handling disabled");
                return;
            }
            //第一个就配置webjars的访问规则，规定在类路径的/META-INF/resources/webjars/路径下，感兴趣的同学可以点进方法去，里面还配置了webjars的浏览器端缓存时间，是在application。propertities中的一个配置项 spring.web.resources.cache.period 
            addResourceHandler(registry, "/webjars/**", "classpath:/META-INF/resources/webjars/");
            //这里配置了静态资源的四个访问路径
            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);
                }
            });
        }

#springapplication.propertities中配置
spring.web.resources.add-mappings=false

spring.mvc.static-path-pattern=/res/**

@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;
        }

WelcomePageHandlerMapping(TemplateAvailabilityProviders templateAvailabilityProviders,
            ApplicationContext applicationContext, Resource welcomePage, String staticPathPattern) {
        if (welcomePage != null && "/**".equals(staticPathPattern)) {
            logger.info("Adding welcome page: " + welcomePage);
            setRootViewName("forward:index.html");
        }
        else if (welcomeTemplateExists(templateAvailabilityProviders, applicationContext)) {
            logger.info("Adding welcome page template: index");
            setRootViewName("index");
        }
    }