SpringBoot——web开发之静态资源映射

1、通过/webjars/**请求静态资源

SpringMVC的相关配置都在WebMvcAutoConfiguration类中，在该类中有一处添加资源映射：

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(getResourceLocations(this.resourceProperties.getStaticLocations())).setCachePeriod(this.getSeconds(cachePeriod)).setCacheControl(cacheControl));
		}

	}
}

该段代码中明示对于所有/webjars/**的请求，如果没有请求映射的处理方法(Controller)则当做静态资源请求处理，都去"classpath:/META-INF/resources/webjars/"中找资源：

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));
}

webjars：以jar包的方式引入静态资源(参考：Web Libraries in Jars)，以maven依赖的方式将静态资源引入到项目中，eg：

	org.webjars
	jquery
	3.3.1-1

 jquery的webjars引入之后在依赖包中可以看到其目录结构：

当我们发/webjars/**请求时会去项目中webjars对应目录去找资源：比如我们要请求jquery.js，需发请求：localhost:8080/webjars/jquery/3.3.1-1/jquery.js，结果如下：

静态资源相关的配置可以参照ResourceProperties，参考该类可以在主配置文件中配置静态资源的缓存时间等：

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

2、自定义静态资源(非webjars的静态资源)：

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

跟踪代码可知staticPathPattern的值是/**，即对于所有的请求，如果没有映射到处理方法，会当做静态资源请求来处理，回去下面的这几个路径下去查找静态资源：

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

静态资源文件夹：

"classpath:/META-INF/resources/"：

"classpath:/resources/"：

"classpath:/static/"：

"classpath:/public/"：

"/"：

就是说我们可以在这些文件夹下放静态资源：

例如我们要访问static下的Chart.min.js：

请求：http://localhost:8080/asserts/js/Chart.min.js即可，注意路径中没有static

3、欢迎页配置：

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

其实就是静态资源文件夹下的index.html，在不指定具体资源的时候就会默认访问该index.html，如果该index.html也不存在，则会返回错误SpringBoot的默认错误页面：

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

例如：访问localhost:8080即可访问到index.html

4、配置喜欢的图标，都是在静态资源文件下找(**/favicon.ico)

@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;
	}

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

	@Bean
	public SimpleUrlHandlerMapping faviconHandlerMapping() {
		SimpleUrlHandlerMapping mapping = new SimpleUrlHandlerMapping();
		mapping.setOrder(-2147483647);
		mapping.setUrlMap(Collections.singletonMap("**/favicon.ico", this.faviconRequestHandler()));
		return mapping;
	}

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

	private List resolveFaviconLocations() {
		String[] staticLocations = WebMvcAutoConfiguration.WebMvcAutoConfigurationAdapter.getResourceLocations(this.resourceProperties.getStaticLocations());
		List locations = new ArrayList(staticLocations.length + 1);
		Stream var10000 = Arrays.stream(staticLocations);
		ResourceLoader var10001 = this.resourceLoader;
		this.resourceLoader.getClass();
		var10000.map(var10001::getResource).forEach(locations::add);
		locations.add(new ClassPathResource("/"));
		return Collections.unmodifiableList(locations);
	}
}

例如：favicon.ico也可以放在其他静态资源文件夹的根路径下

5、自定义静态资源文件夹：值是个数组，配置之后默认的静态资源文件夹都会失效，无法访问

spring.resources.static-locations=classpath:/hello/,classpath:/world/

注意：SpringBoot在改变静态资源的时候也需要重启项目