springboot之web开发之webjars&静态资源映射规则

一、使用springboot

1、创建springboot应用，选中我们需要的模块

2、springboot已经默认将这些场景配置好了，只需要在配置文件中指定少量配置就可以运行起来

3、自己编写业务代码

自动配置原理？

这个场景springboot帮我们配置了什么？能不能修改？能修改哪些配置？能不能扩展？。。。

xxxAutoConfiguration：帮我们给容器中自动配置组件

xxxProperties：配置类中封装配置文件的内容

二、springboot对静态资源的映射规则

1、所有/webjars/**，都去classpath:/META-INF/resources/webjars/找资源

webjars：以jar包的方式引入静态资源

ctrl+n/两次shift找到WebMvcAutoConfiguration类

public void addResourceHandlers(ResourceHandlerRegistry registry) {
    if (!this.resourceProperties.isAddMappings()) {
        logger.debug("Default resource handling disabled");
    } else {
        Duration cachePeriod = this.resourceProperties.getCache().getPeriod();
        CacheControl cacheControl = this.resourceProperties.getCache().getCachecontrol().toHttpCacheControl();
        if (!registry.hasMappingForPattern("/webjars/**")) {
            this.customizeResourceHandlerRegistration(registry.addResourceHandler(new String[]{"/webjars/**"}).addResourceLocations(new String[]{"classpath:/META-INF/resources/webjars/"}).setCachePeriod(this.getSeconds(cachePeriod)).setCacheControl(cacheControl));
        }

        String staticPathPattern = this.mvcProperties.getStaticPathPattern();
        if (!registry.hasMappingForPattern(staticPathPattern)) {
            this.customizeResourceHandlerRegistration(registry.addResourceHandler(new String[]{staticPathPattern}).addResourceLocations(WebMvcAutoConfiguration.getResourceLocations(this.resourceProperties.getStaticLocations())).setCachePeriod(this.getSeconds(cachePeriod)).setCacheControl(cacheControl));
        }

    }
}

pom.xml中添加

<!--引入jquery的webjar-->在访问的时候只需要写webjars下面资源的名称即可
<dependency>
    <groupId>org.webjars</groupId>
    <artifactId>jquery</artifactId>
    <version>3.4.1</version>
</dependency>

将hide。。。的勾去了

重启项目，

​​@ConfigurationProperties(
prefix = "spring.resources",
ignoreUnknownFields = false
)
public class ResourceProperties {//可以设置和静态资源有关的参数，缓存时间等​​

2、"/**" 访问当前项目的任何资源（静态资源的文件夹）

"classpath:/META-INF/resources/",
"classpath:/resources/", 
"classpath:/static/",
"classpath:/public/" 
"/"  ：当前项目的根路径

resources是类路径的根目录

WebMvcAutoConfiguration类addResourceHandlers方法里的staticPathPattern参数跟踪找到WebMvcProperties类里的

private String staticPathPattern = "/**";

addResourceHandlers方法里addResourceLocations资源的位置找到ResourceProperties里的staticLocations

CLASSPATH_RESOURCE_LOCATIONS

public void setStaticLocations(String[] staticLocations) {
   this.staticLocations = appendSlashIfNecessary(staticLocations);
}

private String[] appendSlashIfNecessary(String[] staticLocations) {
   String[] normalized = new String[staticLocations.length];
   for (int i = 0; i < staticLocations.length; i++) {
      String location = staticLocations[i];
      normalized[i] = location.endsWith("/") ? location : location + "/";
   }
   return normalized;
}

localhost:8080/abc===去静态资源文件夹下找abc

​​3、欢迎页，静态资源文件夹下的所有index.html页面，被"/**"映射​​​​localhost:8080/   找index.html页面​​

​​//配置欢迎页映射​​​​@Bean​​​​public WelcomePageHandlerMapping welcomePageHandlerMapping(ApplicationContext applicationContext) {​​

WelcomePageHandlerMapping welcomePageHandlerMapping = new WelcomePageHandlerMapping(
         new TemplateAvailabilityProviders(applicationContext), applicationContext, getWelcomePage(),
         this.mvcProperties.getStaticPathPattern());
   welcomePageHandlerMapping.setInterceptors(getInterceptors());
   return welcomePageHandlerMapping;
}

WebMvcAutoConfiguration类
private Resource getIndexHtml(String location) {
   return this.resourceLoader.getResource(location + "index.html");
}

​​4、所有的**/favicon.ico都是在静态资源文件下找​​

//配置喜欢的图标
@Configuration
   @ConditionalOnProperty(value = "spring.mvc.favicon.enabled", matchIfMissing = true)
   public static class FaviconConfiguration implements ResourceLoaderAware {

      private final ResourceProperties resourceProperties;

      private ResourceLoader resourceLoader;

      public FaviconConfiguration(ResourceProperties resourceProperties) {
         this.resourceProperties = resourceProperties;
      }

      @Override
      public void setResourceLoader(ResourceLoader resourceLoader) {
         this.resourceLoader = resourceLoader;
      }

      @Bean
      public SimpleUrlHandlerMapping faviconHandlerMapping() {
         SimpleUrlHandlerMapping mapping = new SimpleUrlHandlerMapping();
         mapping.setOrder(Ordered.HIGHEST_PRECEDENCE + 1);
         mapping.setUrlMap(Collections.singletonMap("**/favicon.ico", faviconRequestHandler()));
         return mapping;
      }

      @Bean
      public ResourceHttpRequestHandler faviconRequestHandler() {
         ResourceHttpRequestHandler requestHandler = new ResourceHttpRequestHandler();
         requestHandler.setLocations(resolveFaviconLocations());
         return requestHandler;
      }

      private List<Resource> resolveFaviconLocations() {
         String[] staticLocations = getResourceLocations(this.resourceProperties.getStaticLocations());
         List<Resource> locations = new ArrayList<>(staticLocations.length + 1);
         Arrays.stream(staticLocations).map(this.resourceLoader::getResource).forEach(locations::add);
         locations.add(new ClassPathResource("/"));
         return Collections.unmodifiableList(locations);
      }

   }
可以通过配置文件修改静态文件夹的路径