Remove Servlet-specific static locations

This commit removes the Servlet root context from the default values for
the `spring.resources.static-locations` configuration property. Servlet
and non-Servlet applications are sharing this property.

The Servlet root context is automatically configured as a resource
location for Spring MVC based applications.

Closes gh-9240

spring-boot-autoconfigure/src/main/java/org/springframework/boot/autoconfigure/web/ResourceProperties.java

@@ -16,15 +16,7 @@
 
 package org.springframework.boot.autoconfigure.web;
 
-import java.util.ArrayList;
-import java.util.Collections;
-import java.util.List;
-
 import org.springframework.boot.context.properties.ConfigurationProperties;
-import org.springframework.context.ResourceLoaderAware;
-import org.springframework.core.io.ClassPathResource;
-import org.springframework.core.io.Resource;
-import org.springframework.core.io.ResourceLoader;
 
 /**
  * Properties used to configure resource handling.
@@ -36,30 +28,17 @@ import org.springframework.core.io.ResourceLoader;
  * @since 1.1.0
  */
 @ConfigurationProperties(prefix = "spring.resources", ignoreUnknownFields = false)
-public class ResourceProperties implements ResourceLoaderAware {
+public class ResourceProperties {
-
-	private static final String[] SERVLET_RESOURCE_LOCATIONS = { "/" };
 
 	private static final String[] CLASSPATH_RESOURCE_LOCATIONS = {
 			"classpath:/META-INF/resources/", "classpath:/resources/",
 			"classpath:/static/", "classpath:/public/" };
 
-	private static final String[] RESOURCE_LOCATIONS;
-
-	static {
-		RESOURCE_LOCATIONS = new String[CLASSPATH_RESOURCE_LOCATIONS.length
-				+ SERVLET_RESOURCE_LOCATIONS.length];
-		System.arraycopy(SERVLET_RESOURCE_LOCATIONS, 0, RESOURCE_LOCATIONS, 0,
-				SERVLET_RESOURCE_LOCATIONS.length);
-		System.arraycopy(CLASSPATH_RESOURCE_LOCATIONS, 0, RESOURCE_LOCATIONS,
-				SERVLET_RESOURCE_LOCATIONS.length, CLASSPATH_RESOURCE_LOCATIONS.length);
-	}
-
 	/**
 	 * Locations of static resources. Defaults to classpath:[/META-INF/resources/,
-	 * /resources/, /static/, /public/] plus context:/ (the root of the servlet context).
+	 * /resources/, /static/, /public/].
 	 */
-	private String[] staticLocations = RESOURCE_LOCATIONS;
+	private String[] staticLocations = CLASSPATH_RESOURCE_LOCATIONS;
 
 	/**
 	 * Cache period for the resources served by the resource handler, in seconds.
@@ -73,12 +52,6 @@ public class ResourceProperties implements ResourceLoaderAware {
 
 	private final Chain chain = new Chain();
 
-	private ResourceLoader resourceLoader;
-
-	@Override
-	public void setResourceLoader(ResourceLoader resourceLoader) {
-		this.resourceLoader = resourceLoader;
-	}
 
 	public String[] getStaticLocations() {
 		return this.staticLocations;
@@ -97,45 +70,6 @@ public class ResourceProperties implements ResourceLoaderAware {
 		return normalized;
 	}
 
-	public Resource getWelcomePage() {
-		for (String location : getStaticWelcomePageLocations()) {
-			Resource resource = this.resourceLoader.getResource(location);
-			try {
-				if (resource.exists()) {
-					resource.getURL();
-					return resource;
-				}
-			}
-			catch (Exception ex) {
-				// Ignore
-			}
-		}
-		return null;
-	}
-
-	private String[] getStaticWelcomePageLocations() {
-		String[] result = new String[this.staticLocations.length];
-		for (int i = 0; i < result.length; i++) {
-			String location = this.staticLocations[i];
-			if (!location.endsWith("/")) {
-				location = location + "/";
-			}
-			result[i] = location + "index.html";
-		}
-		return result;
-	}
-
-	public List<Resource> resolveFaviconLocations() {
-		List<Resource> locations = new ArrayList<>(this.staticLocations.length + 1);
-		if (this.resourceLoader != null) {
-			for (String location : this.staticLocations) {
-				locations.add(this.resourceLoader.getResource(location));
-			}
-		}
-		locations.add(new ClassPathResource("/"));
-		return Collections.unmodifiableList(locations);
-	}
-
 	public Integer getCachePeriod() {
 		return this.cachePeriod;
 	}

spring-boot-autoconfigure/src/main/java/org/springframework/boot/autoconfigure/web/servlet/WebMvcAutoConfiguration.java

@@ -16,6 +16,8 @@
 
 package org.springframework.boot.autoconfigure.web.servlet;
 
+import java.util.ArrayList;
+import java.util.Arrays;
 import java.util.Collection;
 import java.util.Collections;
 import java.util.Date;
@@ -23,6 +25,7 @@ import java.util.List;
 import java.util.ListIterator;
 import java.util.Map;
 import java.util.Map.Entry;
+import java.util.Optional;
 
 import javax.servlet.Servlet;
 import javax.servlet.http.HttpServletRequest;
@@ -54,6 +57,7 @@ import org.springframework.boot.context.properties.EnableConfigurationProperties
 import org.springframework.boot.web.servlet.filter.OrderedHiddenHttpMethodFilter;
 import org.springframework.boot.web.servlet.filter.OrderedHttpPutFormContentFilter;
 import org.springframework.boot.web.servlet.filter.OrderedRequestContextFilter;
+import org.springframework.context.ResourceLoaderAware;
 import org.springframework.context.annotation.Bean;
 import org.springframework.context.annotation.Configuration;
 import org.springframework.context.annotation.Import;
@@ -62,7 +66,9 @@ import org.springframework.context.annotation.Primary;
 import org.springframework.core.Ordered;
 import org.springframework.core.convert.converter.Converter;
 import org.springframework.core.convert.converter.GenericConverter;
+import org.springframework.core.io.ClassPathResource;
 import org.springframework.core.io.Resource;
+import org.springframework.core.io.ResourceLoader;
 import org.springframework.format.Formatter;
 import org.springframework.format.FormatterRegistry;
 import org.springframework.format.datetime.DateFormatter;
@@ -140,6 +146,8 @@ public class WebMvcAutoConfiguration {
 
 	public static final String DEFAULT_SUFFIX = "";
 
+	private static final String[] SERVLET_LOCATIONS = { "/" };
+
 	@Bean
 	@ConditionalOnMissingBean(HiddenHttpMethodFilter.class)
 	public OrderedHiddenHttpMethodFilter hiddenHttpMethodFilter() {
@@ -158,7 +166,7 @@ public class WebMvcAutoConfiguration {
 	@Configuration
 	@Import(EnableWebMvcConfiguration.class)
 	@EnableConfigurationProperties({ WebMvcProperties.class, ResourceProperties.class })
-	public static class WebMvcAutoConfigurationAdapter implements WebMvcConfigurer {
+	public static class WebMvcAutoConfigurationAdapter implements WebMvcConfigurer, ResourceLoaderAware {
 
 		private static final Log logger = LogFactory.getLog(WebMvcConfigurer.class);
 
@@ -172,6 +180,8 @@ public class WebMvcAutoConfiguration {
 
 		final ResourceHandlerRegistrationCustomizer resourceHandlerRegistrationCustomizer;
 
+		private ResourceLoader resourceLoader;
+
 		public WebMvcAutoConfigurationAdapter(ResourceProperties resourceProperties,
 				WebMvcProperties mvcProperties, ListableBeanFactory beanFactory,
 				@Lazy HttpMessageConverters messageConverters,
@@ -184,6 +194,11 @@ public class WebMvcAutoConfiguration {
 					.getIfAvailable();
 		}
 
+		@Override
+		public void setResourceLoader(ResourceLoader resourceLoader) {
+			this.resourceLoader = resourceLoader;
+		}
+
 		@Override
 		public void configureMessageConverters(List<HttpMessageConverter<?>> converters) {
 			converters.addAll(this.messageConverters.getConverters());
@@ -302,18 +317,43 @@ public class WebMvcAutoConfiguration {
 				customizeResourceHandlerRegistration(
 						registry.addResourceHandler(staticPathPattern)
 								.addResourceLocations(
-										this.resourceProperties.getStaticLocations())
+										getResourceLocations(this.resourceProperties.getStaticLocations()))
 						.setCachePeriod(cachePeriod));
 			}
 		}
 
 		@Bean
-		public WelcomePageHandlerMapping welcomePageHandlerMapping(
+		public WelcomePageHandlerMapping welcomePageHandlerMapping() {
-				ResourceProperties resourceProperties) {
+			return new WelcomePageHandlerMapping(getWelcomePage(),
-			return new WelcomePageHandlerMapping(resourceProperties.getWelcomePage(),
 					this.mvcProperties.getStaticPathPattern());
 		}
 
+		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;
+		}
+
+		private Optional<Resource> getWelcomePage() {
+			return Arrays.stream(getResourceLocations(this.resourceProperties.getStaticLocations()))
+					.map(location -> this.resourceLoader.getResource(location + "index.html"))
+					.filter(resource -> {
+						try {
+							if (resource.exists()) {
+								resource.getURL();
+								return true;
+							}
+						}
+						catch (Exception ex) {
+							// Ignore
+						}
+						return false;
+					})
+					.findFirst();
+		}
+
 		private void customizeResourceHandlerRegistration(
 				ResourceHandlerRegistration registration) {
 			if (this.resourceHandlerRegistrationCustomizer != null) {
@@ -331,14 +371,21 @@ public class WebMvcAutoConfiguration {
 
 		@Configuration
 		@ConditionalOnProperty(value = "spring.mvc.favicon.enabled", matchIfMissing = true)
-		public static class FaviconConfiguration {
+		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();
@@ -351,11 +398,19 @@ public class WebMvcAutoConfiguration {
 			@Bean
 			public ResourceHttpRequestHandler faviconRequestHandler() {
 				ResourceHttpRequestHandler requestHandler = new ResourceHttpRequestHandler();
-				requestHandler
+				requestHandler.setLocations(resolveFaviconLocations());
-						.setLocations(this.resourceProperties.resolveFaviconLocations());
 				return requestHandler;
 			}
 
+			private List<Resource> resolveFaviconLocations() {
+				String[] resourceLocations = getResourceLocations(this.resourceProperties.getStaticLocations());
+				List<Resource> locations = new ArrayList<>(resourceLocations.length + 1);
+				Arrays.stream(resourceLocations)
+						.forEach(location -> locations.add(this.resourceLoader.getResource(location)));
+				locations.add(new ClassPathResource("/"));
+				return Collections.unmodifiableList(locations);
+			}
+
 		}
 
 	}
@@ -546,9 +601,9 @@ public class WebMvcAutoConfiguration {
 		private static final Log logger = LogFactory
 				.getLog(WelcomePageHandlerMapping.class);
 
-		private WelcomePageHandlerMapping(Resource welcomePage,
+		private WelcomePageHandlerMapping(Optional<Resource> welcomePage,
 				String staticPathPattern) {
-			if (welcomePage != null && "/**".equals(staticPathPattern)) {
+			if (welcomePage.isPresent() && "/**".equals(staticPathPattern)) {
 				logger.info("Adding welcome page: " + welcomePage);
 				ParameterizableViewController controller = new ParameterizableViewController();
 				controller.setViewName("forward:index.html");

spring-boot-autoconfigure/src/test/java/org/springframework/boot/autoconfigure/web/reactive/WebFluxAutoConfigurationTests.java

@@ -127,7 +127,7 @@ public class WebFluxAutoConfigurationTests {
 				SimpleUrlHandlerMapping.class);
 		assertThat(hm.getUrlMap().get("/**")).isInstanceOf(ResourceWebHandler.class);
 		ResourceWebHandler staticHandler = (ResourceWebHandler) hm.getUrlMap().get("/**");
-		assertThat(staticHandler.getLocations()).hasSize(5);
+		assertThat(staticHandler.getLocations()).hasSize(4);
 		assertThat(hm.getUrlMap().get("/webjars/**"))
 				.isInstanceOf(ResourceWebHandler.class);
 		ResourceWebHandler webjarsHandler = (ResourceWebHandler) hm.getUrlMap()
@@ -146,7 +146,7 @@ public class WebFluxAutoConfigurationTests {
 				.isInstanceOf(ResourceWebHandler.class);
 		ResourceWebHandler staticHandler = (ResourceWebHandler) hm.getUrlMap()
 				.get("/static/**");
-		assertThat(staticHandler.getLocations()).hasSize(5);
+		assertThat(staticHandler.getLocations()).hasSize(4);
 	}
 
 	@Test

spring-boot-autoconfigure/src/test/java/org/springframework/boot/autoconfigure/web/servlet/WebMvcAutoConfigurationTests.java

@@ -442,7 +442,7 @@ public class WebMvcAutoConfigurationTests {
 				.withPropertyValues("spring.resources.static-locations=classpath:/static")
 				.run((context) -> assertThat(
 						getFaviconMappingLocations(context).get("/**/favicon.ico"))
-								.hasSize(2));
+								.hasSize(3));
 	}
 
 	@Test

spring-boot-docs/src/main/asciidoc/spring-boot-features.adoc

@@ -1900,10 +1900,11 @@ can be achieved as follows:
 ----
 
 You can also customize the static resource locations using
-`spring.resources.static-locations` (replacing the default values with a list of directory
+`spring.resources.static-locations` (replacing the default values with a list
-locations). If you do this the default welcome page detection will switch to your custom
+of directory locations). The root Servlet context path `"/"` will be automatically
-locations, so if there is an `index.html` in any of your locations on startup, it will be
+added as a location as well. If you do this the default welcome page detection will
-the home page of the application.
+switch to your custom locations, so if there is an `index.html` in any of your locations
+on startup, it will be the home page of the application.
 
 In addition to the '`standard`' static resource locations above, a special case is made
 for http://www.webjars.org/[Webjars content]. Any resources with a path in `+/webjars/**+`
@@ -2249,7 +2250,7 @@ Unlike Spring MVC, it does not require the Servlet API, is fully asynchronous an
 non-blocking, and implements the http://www.reactive-streams.org/[Reactive Streams]
 specification through http://projectreactor.io/[the Reactor project].
 
-Spring WebFlux comes in two flavors — the annotation-based one is quite close to the
+Spring WebFlux comes in two flavors; the annotation-based one is quite close to the
 Spring MVC model we know:
 
 [source,java,indent=0]
@@ -3066,7 +3067,7 @@ auto-configured. In this example it's pulled in transitively via
 `spring-boot-starter-data-jpa`.
 
 TIP: If, for whatever reason, you do configure the connection URL for an embedded
-database, care should be taken to ensure that the database’s automatic shutdown is
+database, care should be taken to ensure that the database's automatic shutdown is
 disabled. If you're using H2 you should use `DB_CLOSE_ON_EXIT=FALSE` to do so. If you're
 using HSQLDB, you should ensure that `shutdown=true` is not used. Disabling the database's
 automatic shutdown allows Spring Boot to control when the database is closed, thereby
@@ -4573,7 +4574,7 @@ recommend to keep this setting enabled if you create your own `RedisCacheManager
 
 [[boot-features-caching-provider-caffeine]]
 ==== Caffeine
-Caffeine is a Java 8 rewrite of Guava’s cache that supersede the Guava support. If
+Caffeine is a Java 8 rewrite of Guava's cache that supersede the Guava support. If
 Caffeine is present, a `CaffeineCacheManager` (provided by the
 `spring-boot-starter-cache` '`Starter`') is auto-configured. Caches can be created
 on startup using the `spring.cache.cache-names` property and customized by one of the