SpringBoot之加載靜態資源

默認靜態資源路徑及優先級

SpringBoot對於各組件的自動配置一般都是在spring-boot-autoconfigure包中，
重點查看一下兩類文件：

• ***AutoConfiguration
• ***Properties

因此直接查看Web相關包，可以看到org.springframework.boot.autoconfigure.web.servlet.WebMvcAutoConfiguration有addResourceHandlers方法：

public void addResourceHandlers(ResourceHandlerRegistry registry) {
			//是否啓動默認靜態資源映射
			if (!this.resourceProperties.isAddMappings()) {
				logger.debug("Default resource handling disabled");
				return;
			}
			//資源文件緩存
			Duration cachePeriod = this.resourceProperties.getCache().getPeriod();
			CacheControl cacheControl = this.resourceProperties.getCache()
					.getCachecontrol().toHttpCacheControl();
			// 如果容器中有的話，加載classpath下/webjars/**
			if (!registry.hasMappingForPattern("/webjars/**")) {
				customizeResourceHandlerRegistration(registry
						.addResourceHandler("/webjars/**")
						.addResourceLocations("classpath:/META-INF/resources/webjars/")
						.setCachePeriod(getSeconds(cachePeriod))
						.setCacheControl(cacheControl));
			}
			// 獲取靜態資源默認映射路徑，默認爲/**
			String staticPathPattern = this.mvcProperties.getStaticPathPattern();
			if (!registry.hasMappingForPattern(staticPathPattern)) {
				customizeResourceHandlerRegistration(
						// 加載默認靜態資源
						registry.addResourceHandler(staticPathPattern)
								// 默認靜態資源
								.addResourceLocations(getResourceLocations(
										this.resourceProperties.getStaticLocations()))
								.setCachePeriod(getSeconds(cachePeriod))
								.setCacheControl(cacheControl));
			}
		}

org.springframework.boot.autoconfigure.web.servlet.WebMvcProperties

@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;
//......
	//獲取靜態資源默認路徑
	static String[] getResourceLocations(String[] staticLocations) {
			String[] locations = new String[staticLocations.length
					+ SERVLET_LOCATIONS.length];
			System.arraycopy(staticLocations, 0, locations, 0, staticLocations.length);
			System.arraycopy(SERVLET_LOCATIONS, 0, locations, staticLocations.length,
					SERVLET_LOCATIONS.length);
			return locations;
		}

由此可以知道SpringBoot中，默認靜態資源的訪問路徑爲：

1. classpath:/META-INF/resources/
2. classpath:/resources/
3. classpath:/static/
4. classpath:/public/

此默認路徑優先級由高到低。

自定義資源路徑以及映射

# 不會覆蓋默認靜態資源路徑
spring:
  resources:
    static-locations: classpath:/mystatic/,classpath:/otherstatic/
# 只有在訪問路徑中有該路徑時方可訪問靜態資源，如果設置了servlet-context,那麼也需要在路徑中加入。
  mvc:
    static-path-pattern: /mystatic