自动配置原理

  • xxxAutoConfiguration：给容器中自动配置组件
  • xxxProperties：封装配置文件的配置类

映射静态资源

Web自动配置类：WebMvcAutoConfiguration
Web配置的封装类：MvcProperties 和 ResourceProperties

配置和资源有关的参数：

  1. @ConfigurationProperties(prefix = "spring.resources", ignoreUnknownFields = false)
  2. public class ResourceProperties {
  3.     private static final String[] CLASSPATH_RESOURCE_LOCATIONS = { "classpath:/META-INF/resources/",
  4.                                                                   "classpath:/resources/", "classpath:/static/", "classpath:/public/" };
  5.     private String[] staticLocations = CLASSPATH_RESOURCE_LOCATIONS;
  6.     ...
  7. }

下面的代码是 WebMvcAutoConfiguration 类的静态资源加载方法的源码：

  1. // 静态资源配置类
  2. @Override
  3. public void addResourceHandlers(ResourceHandlerRegistry registry) {
  4.     if (!this.resourceProperties.isAddMappings()) {
  5.         logger.debug("Default resource handling disabled");
  6.         return;
  7.     }
  8.     Duration cachePeriod = this.resourceProperties.getCache().getPeriod();
  9.     CacheControl cacheControl = this.resourceProperties.getCache().getCachecontrol().toHttpCacheControl();
  10.     if (!registry.hasMappingForPattern("/webjars/**")) {
  11.         customizeResourceHandlerRegistration(registry.addResourceHandler("/webjars/**")
  12.                                              .addResourceLocations("classpath:/META-INF/resources/webjars/")
  13.                                              .setCachePeriod(getSeconds(cachePeriod)).setCacheControl(cacheControl));
  14.     }
  15.     String staticPathPattern = this.mvcProperties.getStaticPathPattern();
  16.     if (!registry.hasMappingForPattern(staticPathPattern)) {
  17.         customizeResourceHandlerRegistration(registry.addResourceHandler(staticPathPattern)
  18.                                              .addResourceLocations(getResourceLocations(this.resourceProperties.getStaticLocations()))
  19.                                              .setCachePeriod(getSeconds(cachePeriod)).setCacheControl(cacheControl));
  20.     }
  21. }

1、所有的 /webjars/** ，在 classpath:/META-INF/resources/webjars/ 中寻找资源：

  • webjars 网站：https://www.webjars.org/
  • WebJars 是将客户端（浏览器）网络资源库（例如 jQuery 或者 Bootstrap）打包成 JAR 文件，然后通过 maven 依赖导入，通过 localhost:8080/webjars/jquery/3.5.1/jquery.js 访问

image.png

2、String staticPathPattern = this.mvcProperties.getStaticPathPattern(); 在 MvcProperties 配置类找到该参数： 

  1. /**
  2. * ResourceProperties 资源路径配置类中的一个参数
  3. */
  4. private String staticPathPattern = "/**";

getResourceLocations(this.resourceProperties.getStaticLocations()) 静态资源的默认位置在 ResourceProperties 的源码中可以找到：

  • classpath:/META-INF/resources/
  • classpath:/resources/
  • classpath:/static/
  • classpath:/public/

自定义静态资源位置：通过 ResourceProperties 配置类中的 staticLocations 属性，因此，一旦自定义了资源位置，默认配置就会失效

  1. spring:
  2.   resources:
  3.     static-locations: /static/

3、欢迎页：静态资源文件夹的所有 index.html 页面，同时被 /** 映射

  1. /* WebMvcAutoConfiguration 的静态内部类 EnableWebMvcConfiguration 中的方法 */
  2. @Bean
  3. public WelcomePageHandlerMapping welcomePageHandlerMapping(ApplicationContext applicationContext,
  4.                                                            FormattingConversionService mvcConversionService, ResourceUrlProvider mvcResourceUrlProvider) {
  5.     WelcomePageHandlerMapping welcomePageHandlerMapping = new WelcomePageHandlerMapping(
  6.         new TemplateAvailabilityProviders(applicationContext), applicationContext, getWelcomePage(),
  7.         this.mvcProperties.getStaticPathPattern());
  8.     welcomePageHandlerMapping.setInterceptors(getInterceptors(mvcConversionService, mvcResourceUrlProvider));
  9.     welcomePageHandlerMapping.setCorsConfigurations(getCorsConfigurations());
  10.     return welcomePageHandlerMapping;
  11. }
  12. private Optional<Resource> getWelcomePage() {
  13.     String[] locations = getResourceLocations(this.resourceProperties.getStaticLocations());
  14.     return Arrays.stream(locations).map(this::getIndexHtml).filter(this::isReadable).findFirst();
  15. }
  16. private Resource getIndexHtml(String location) {
  17.     // 拼凑出欢迎页的资源路径
  18.     return this.resourceLoader.getResource(location + "index.html");
  19. }
  21. /* WelcomePageHandlerMapping */
  22. WelcomePageHandlerMapping(TemplateAvailabilityProviders templateAvailabilityProviders,
  23.                           ApplicationContext applicationContext, Optional<Resource> welcomePage, String staticPathPattern) {
  24.     // 欢迎页的映射，/**会被重定向
  25.     if (welcomePage.isPresent() && "/**".equals(staticPathPattern)) {
  26.         logger.info("Adding welcome page: " + welcomePage.get());
  27.         setRootViewName("forward:index.html");
  28.     }
  29.     else if (welcomeTemplateExists(templateAvailabilityProviders, applicationContext)) {
  30.         logger.info("Adding welcome page template: index");
  31.         setRootViewName("index");
  32.     }
  33. }


4、图标资源：在静态资源文件下找 /favicon.ico