目录
一、静态资源配置原理
* SpringBoot启动默认加载 xxxAutoConfiguration 类（自动配置类）
* SpringMVC功能的自动配置类 WebMvcAutoConfiguration，生效
1.自动配置类
@Configuration(proxyBeanMethods = false) // 不会被代理
@ConditionalOnWebApplication(type = Type.SERVLET) // 是servlet项目
@ConditionalOnClass({ Servlet.class, DispatcherServlet.class, WebMvcConfigurer.class }) // 有这几个类，导入springmvc的包就会有这几个类
@ConditionalOnMissingBean(WebMvcConfigurationSupport.class) // 容器中没有这个类型的组件时下面才会生效。（要全面接管springmvc）
@AutoConfigureOrder(Ordered.HIGHEST_PRECEDENCE + 10)
@AutoConfigureAfter({ DispatcherServletAutoConfiguration.class, TaskExecutionAutoConfiguration.class,
ValidationAutoConfiguration.class })
public class WebMvcAutoConfiguration {
2.自动配置类的内部类
（1）配置文件的相关属性和xxx进行了绑定。
WebMvcProperties==spring.mvc、ResourceProperties==spring.resources
@SuppressWarnings("deprecation")
@Configuration(proxyBeanMethods = false)
@Import(EnableWebMvcConfiguration.class)
@EnableConfigurationProperties({ WebMvcProperties.class,
org.springframework.boot.autoconfigure.web.ResourceProperties.class, WebProperties.class }) // 将配置文件与这几个类绑定，并且导入到ioc容器中。
@Order(0)
public static class WebMvcAutoConfigurationAdapter implements WebMvcConfigurer {
（2）这个内部类只有一个有参构造器：
//有参构造器所有参数的值都会从容器中确定
//ResourceProperties resourceProperties；获取和spring.resources绑定的所有的值的对象
//WebMvcProperties mvcProperties 获取和spring.mvc绑定的所有的值的对象
//ListableBeanFactory beanFactory Spring的beanFactory
//HttpMessageConverters 找到所有的HttpMessageConverters
//ResourceHandlerRegistrationCustomizer 找到 资源处理器的自定义器。=========
//DispatcherServletPath 路径处理器
//ServletRegistrationBean 给应用注册Servlet、Filter、Listener....
public WebMvcAutoConfigurationAdapter(
org.springframework.boot.autoconfigure.web.ResourceProperties resourceProperties,
WebProperties webProperties, WebMvcProperties mvcProperties, ListableBeanFactory beanFactory,
ObjectProvider<HttpMessageConverters> messageConvertersProvider,
ObjectProvider<ResourceHandlerRegistrationCustomizer> resourceHandlerRegistrationCustomizerProvider,
ObjectProvider<DispatcherServletPath> dispatcherServletPath,
ObjectProvider<ServletRegistrationBean<?>> servletRegistrations) {
this.resourceProperties = resourceProperties.hasBeenCustomized() ? 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();
}
（3）资源处理的默认规则
@Override
public void addResourceHandlers(ResourceHandlerRegistry registry) {
// 如果配置isAddMappings 配置为false，下面所有配置都不生效，默认为true。
if (!this.resourceProperties.isAddMappings()) {
logger.debug("Default resource handling disabled");
return;
}
// 缓存
Duration cachePeriod = this.resourceProperties.getCache().getPeriod();
CacheControl cacheControl = this.resourceProperties.getCache().getCachecontrol().toHttpCacheControl();
// webjars的规则，也可以缓存
if (!registry.hasMappingForPattern("/webjars/**")) {
customizeResourceHandlerRegistration(registry.addResourceHandler("/webjars/**")
.addResourceLocations("classpath:/META-INF/resources/webjars/")
.setCachePeriod(getSeconds(cachePeriod)).setCacheControl(cacheControl)
.setUseLastModified(this.resourceProperties.getCache().isUseLastModified()));
}
// staticPathPattern配置的请求（默认是/**）
String staticPathPattern = this.mvcProperties.getStaticPathPattern();
if (!registry.hasMappingForPattern(staticPathPattern)) {
customizeResourceHandlerRegistration(registry.addResourceHandler(staticPathPattern)
.addResourceLocations(getResourceLocations(this.resourceProperties.getStaticLocations()))
.setCachePeriod(getSeconds(cachePeriod)).setCacheControl(cacheControl)
.setUseLastModified(this.resourceProperties.getCache().isUseLastModified()));
}
}
spring:
resources:
add-mappings: false 禁用所有静态资源规则
// 静态资源默认的四个位置
@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;
（4）欢迎页的处理规则
// HandlerMapping：处理器映射。保存了每一个Handler能处理哪些请求。
@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;
}
// new WelcomePageHandlerMapping
WelcomePageHandlerMapping(TemplateAvailabilityProviders templateAvailabilityProviders,
ApplicationContext applicationContext, Optional<Resource> welcomePage, String staticPathPattern) {
//要用欢迎页功能，静态资源路径必须是/**
if (welcomePage.isPresent() && "/**".equals(staticPathPattern)) {
logger.info("Adding welcome page: " + welcomePage.get());
setRootViewName("forward:index.html");
}
else if (welcomeTemplateExists(templateAvailabilityProviders, applicationContext)) {
// 调用Controller /index
logger.info("Adding welcome page template: index");
setRootViewName("index");
}
}
（5）favicon
favicon跟代码没什么关系，是浏览器会自动发送/favicon.ico，进行查找favicon。
