SpringBoot对外部资源的映射规则

根据SpringBoot自动配置源码：

配置资源有关的参数

@ConfigurationProperties(prefix = "spring.resources", ignoreUnknownFields = false)
public class ResourceProperties {

    private static final String[] CLASSPATH_RESOURCE_LOCATIONS = { "classpath:/META-INF/resources/",
            "classpath:/resources/", "classpath:/static/", "classpath:/public/" };

    /**
     * Locations of static resources. Defaults to classpath:[/META-INF/resources/,
     * /resources/, /static/, /public/].
     */
    private String[] staticLocations = CLASSPATH_RESOURCE_LOCATIONS;
  ...

根据以上源码，我们可以手动通过spring.resources属性去配置和资源有关的参数

webjars的方式引入资源

@Override
public void addResourceHandlers(ResourceHandlerRegistry registry) {
  if (!this.resourceProperties.isAddMappings()) {
    logger.debug("Default resource handling disabled");
    return;
  }
  Duration cachePeriod = this.resourceProperties.getCache().getPeriod();
  CacheControl cacheControl = this.resourceProperties.getCache().getCachecontrol().toHttpCacheControl();
  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));
  }
}

• 可以看出，所有的/webjars/**都会映射到classpath:/META-INF/resources/webjars/

• webjars:以jar包的方式引入静态资源 webjars官网

  例如我们需要使用jquery，直接引入依赖即可

  <dependency>
      <groupId>org.webjars</groupId>
      <artifactId>jquery</artifactId>
      <version>3.4.1</version>
  </dependency>

  之后在http://localhost:8080/webjars/jquery/3.4.1/jquery.js就可访问到jquery

/**访问当前项目的任何资源

@ConfigurationProperties(prefix = "spring.resources", ignoreUnknownFields = false)
public class ResourceProperties {

    private static final String[] CLASSPATH_RESOURCE_LOCATIONS = { "classpath:/META-INF/resources/",
            "classpath:/resources/", 
       "classpath:/static/", 
       "classpath:/public/" };

以上源码可以看出"classpath:/resources/", "classpath:/static/", "classpath:/public/" 为静态资源的文件夹，若访问/**，默认会在以上几个文件夹去寻找，没有的目录可手动创建

首页映射

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

getStaticPathPattern())可知，仍然会去静态资源的文件夹下去寻找首页