【SpringBoot】welcome与favicon功能以及一些底层

欢迎页配置

默认放在static文件夹下，index.html即为欢迎页

手动修改欢迎页的位置

在application.yaml文件中配置如下

spring:
  web:
    resources:
      static-locations: [classpath:/haha/]

 注意：可以配置静态资源路径，但不可以配置静态资源的访问前缀，否则导致index.html不能被默认访问

Favicon

将图标放到静态资源路径，默认是static，因为上面我们改了，所以是haha路径下，图标命名应为favicon.ico

注意：如果浏览器访问网站时网站还没有图标，后配置，但是浏览器没关，以后图标都不会出现，这是因为浏览器session的缘故，所以需要换一个浏览器尝试，同样也不可以配置静态资源路径前缀，否则会影响功能的实现。

底层分析

大多数配置都在这个Servlet文件夹里

 给容器中配了什么

@Configuration(proxyBeanMethods = false)
@Import(EnableWebMvcConfiguration.class)
@EnableConfigurationProperties({ WebMvcProperties.class, WebProperties.class })
@Order(0)
public static class WebMvcAutoConfigurationAdapter implements WebMvcConfigurer, ServletContextAware {}

WebMvcProperties.class和spring.mvc进行了绑定，WebProperties和spring.web进行了绑定

 配置类只有一个有参构造器

有参构造的所有参数的值都会在构造器中确定

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();
    }

分析：

 禁用静态资源

@Override
public void addResourceHandlers(ResourceHandlerRegistry registry) {
  if (!this.resourceProperties.isAddMappings()) {
    logger.debug("Default resource handling disabled");
    return;
  }
  addResourceHandler(registry, "/webjars/**", "classpath:/META-INF/resources/webjars/");
  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);
        }
      });
    }

当add-mappings：false时，所有的静态资源都被禁用 

 设置缓存的时间

 Webjars的规则

@Override
public void addResourceHandlers(ResourceHandlerRegistry registry) {
  if (!this.resourceProperties.isAddMappings()) {
    logger.debug("Default resource handling disabled");
    return;
    }
  addResourceHandler(registry, "/webjars/**", "classpath:/META-INF/resources/webjars/");
  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);
        }
      });
    }

搜索webjars的时候，会沿着该路径往下找

欢迎页

@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;
}

这个地方是写死的，所以不能修改静态网页的前缀