Add additional ViewResolver configuration

The DispatcherServlet adds a default InternalViewResolver
which was used by some apps, but when the actuator was
available it added an "/error" bean and effectively
switched off the default view resolver. The net fix was
to add an InternalViewResolver at the same time as
adding any other ViewResolvers.

[Fixes #55357516] [bs-290] Actuator UI app cannot serve static index.html

spring-boot-autoconfigure/src/main/java/org/springframework/boot/autoconfigure/thymeleaf/ThymeleafAutoConfiguration.java

@@ -34,6 +34,7 @@ import org.springframework.boot.autoconfigure.condition.ConditionalOnMissingBean
 import org.springframework.boot.autoconfigure.web.WebMvcAutoConfiguration;
 import org.springframework.context.annotation.Bean;
 import org.springframework.context.annotation.Configuration;
+import org.springframework.core.Ordered;
 import org.springframework.core.io.DefaultResourceLoader;
 import org.springframework.core.io.ResourceLoader;
 import org.thymeleaf.TemplateProcessingParameters;
@@ -153,6 +154,9 @@ public class ThymeleafAutoConfiguration {
 			ThymeleafViewResolver resolver = new ThymeleafViewResolver();
 			resolver.setTemplateEngine(this.templateEngine);
 			resolver.setCharacterEncoding("UTF-8");
+			// Needs to come before any fallback resolver (e.g. a
+			// InternalResourceViewResolver)
+			resolver.setOrder(Ordered.LOWEST_PRECEDENCE - 20);
 			return resolver;
 		}
 

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

@@ -58,6 +58,7 @@ import org.springframework.web.servlet.handler.SimpleUrlHandlerMapping;
 import org.springframework.web.servlet.resource.ResourceHttpRequestHandler;
 import org.springframework.web.servlet.view.BeanNameViewResolver;
 import org.springframework.web.servlet.view.ContentNegotiatingViewResolver;
+import org.springframework.web.servlet.view.InternalResourceViewResolver;
 
 /**
  * {@link EnableAutoConfiguration Auto-configuration} for {@link EnableWebMvc Web MVC}.
@@ -110,6 +111,14 @@ public class WebMvcAutoConfiguration {
 		@Autowired
 		private ResourceLoader resourceLoader;
 
+		@ConditionalOnBean(View.class)
+		@ConditionalOnMissingBean(InternalResourceViewResolver.class)
+		@Bean
+		public InternalResourceViewResolver defaultViewResolver() {
+			InternalResourceViewResolver resolver = new InternalResourceViewResolver();
+			return resolver;
+		}
+
 		@ConditionalOnBean(View.class)
 		@Bean
 		public BeanNameViewResolver beanNameViewResolver() {
@@ -124,6 +133,9 @@ public class WebMvcAutoConfiguration {
 			ContentNegotiatingViewResolver resolver = new ContentNegotiatingViewResolver();
 			resolver.setContentNegotiationManager(beanFactory
 					.getBean(ContentNegotiationManager.class));
+			// ContentNegotiatingViewResolver uses all the other view resolvers to locate
+			// a view so it should have a high precedence
+			resolver.setOrder(Ordered.HIGHEST_PRECEDENCE);
 			return resolver;
 		}
 

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

@@ -25,7 +25,6 @@ import org.junit.After;
 import org.junit.Rule;
 import org.junit.Test;
 import org.junit.rules.ExpectedException;
-import org.springframework.boot.autoconfigure.web.WebMvcAutoConfiguration;
 import org.springframework.boot.context.embedded.AnnotationConfigEmbeddedWebApplicationContext;
 import org.springframework.boot.context.embedded.EmbeddedServletContainerCustomizerBeanPostProcessor;
 import org.springframework.boot.context.embedded.EmbeddedServletContainerFactory;
@@ -35,7 +34,6 @@ import org.springframework.context.annotation.Configuration;
 import org.springframework.web.servlet.HandlerAdapter;
 import org.springframework.web.servlet.HandlerMapping;
 import org.springframework.web.servlet.View;
-import org.springframework.web.servlet.ViewResolver;
 import org.springframework.web.servlet.view.AbstractView;
 
 import static org.junit.Assert.assertEquals;
@@ -78,15 +76,6 @@ public class WebMvcAutoConfigurationTests {
 		assertEquals(6, this.context.getBeanNamesForType(HandlerMapping.class).length);
 	}
 
-	@Test
-	public void viewResolversCreatedIfViewsPresent() throws Exception {
-		this.context = new AnnotationConfigEmbeddedWebApplicationContext();
-		this.context.register(Config.class, ViewConfig.class,
-				WebMvcAutoConfiguration.class);
-		this.context.refresh();
-		assertEquals(2, this.context.getBeanNamesForType(ViewResolver.class).length);
-	}
-
 	@Configuration
 	protected static class ViewConfig {
 

spring-boot-samples/spring-boot-sample-web-static/pom.xml

@@ -19,6 +19,11 @@
 			<artifactId>spring-boot-starter-web</artifactId>
 			<version>${project.version}</version>
 		</dependency>
+		<dependency>
+			<groupId>${project.groupId}</groupId>
+			<artifactId>spring-boot-starter-actuator</artifactId>
+			<version>${project.version}</version>
+		</dependency>
 		<dependency>
 			<groupId>${project.groupId}</groupId>
 			<artifactId>spring-boot-starter-tomcat</artifactId>