Extract DispatcherServletAutoConfiguration so it can be used independently

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

+/*
+ * Copyright 2012-2013 the original author or authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.springframework.boot.autoconfigure.web;
+
+import java.util.Arrays;
+
+import org.springframework.beans.factory.config.ConfigurableListableBeanFactory;
+import org.springframework.boot.autoconfigure.AutoConfigureAfter;
+import org.springframework.boot.autoconfigure.EnableAutoConfiguration;
+import org.springframework.boot.autoconfigure.condition.ConditionalOnClass;
+import org.springframework.boot.autoconfigure.condition.SpringBootCondition;
+import org.springframework.context.annotation.Bean;
+import org.springframework.context.annotation.ConditionContext;
+import org.springframework.context.annotation.Conditional;
+import org.springframework.context.annotation.Configuration;
+import org.springframework.core.Ordered;
+import org.springframework.core.annotation.Order;
+import org.springframework.core.type.AnnotatedTypeMetadata;
+import org.springframework.web.servlet.DispatcherServlet;
+
+/**
+ * {@link EnableAutoConfiguration Auto-configuration} for an the Spring
+ * {@link DispatcherServlet} servlet containers.
+ * 
+ * @author Phillip Webb
+ * @author Dave Syer
+ */
+@Order(Ordered.HIGHEST_PRECEDENCE)
+@Configuration
+@ConditionalOnClass(DispatcherServlet.class)
+@AutoConfigureAfter(EmbeddedServletContainerAutoConfiguration.class)
+public class DispatcherServletAutoConfiguration {
+
+	/*
+	 * The bean name for a DispatcherServlet that will be mapped to the root URL "/"
+	 */
+	public static final String DEFAULT_DISPATCHER_SERVLET_BEAN_NAME = "dispatcherServlet";
+
+	@Bean(name = DEFAULT_DISPATCHER_SERVLET_BEAN_NAME)
+	@Conditional(DefaultDispatcherServletCondition.class)
+	public DispatcherServlet dispatcherServlet() {
+		return new DispatcherServlet();
+	}
+
+	private static class DefaultDispatcherServletCondition extends SpringBootCondition {
+
+		@Override
+		public Outcome getMatchOutcome(ConditionContext context,
+				AnnotatedTypeMetadata metadata) {
+
+			ConfigurableListableBeanFactory beanFactory = context.getBeanFactory();
+			String[] beans = beanFactory.getBeanNamesForType(DispatcherServlet.class,
+					false, false);
+			if (beans.length == 0) {
+				return Outcome.match("no DispatcherServlet found");
+			}
+			if (Arrays.asList(beans).contains(DEFAULT_DISPATCHER_SERVLET_BEAN_NAME)) {
+				return Outcome.noMatch("found DispatcherServlet named "
+						+ DEFAULT_DISPATCHER_SERVLET_BEAN_NAME);
+			}
+			return Outcome
+					.match("one or more DispatcherServlets found and none is named "
+							+ DEFAULT_DISPATCHER_SERVLET_BEAN_NAME);
+		}
+	}
+
+}

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

@@ -16,8 +16,6 @@
 
 package org.springframework.boot.autoconfigure.web;
 
-import java.util.Arrays;
-
 import javax.servlet.Servlet;
 
 import org.apache.catalina.startup.Tomcat;
@@ -34,24 +32,18 @@ import org.springframework.boot.autoconfigure.EnableAutoConfiguration;
 import org.springframework.boot.autoconfigure.condition.ConditionalOnClass;
 import org.springframework.boot.autoconfigure.condition.ConditionalOnMissingBean;
 import org.springframework.boot.autoconfigure.condition.SearchStrategy;
-import org.springframework.boot.autoconfigure.condition.SpringBootCondition;
 import org.springframework.boot.autoconfigure.web.EmbeddedServletContainerAutoConfiguration.EmbeddedServletContainerCustomizerBeanPostProcessorRegistrar;
 import org.springframework.boot.context.embedded.EmbeddedServletContainerCustomizerBeanPostProcessor;
 import org.springframework.boot.context.embedded.EmbeddedServletContainerFactory;
-import org.springframework.boot.context.embedded.ServletContextInitializer;
 import org.springframework.boot.context.embedded.jetty.JettyEmbeddedServletContainerFactory;
 import org.springframework.boot.context.embedded.tomcat.TomcatEmbeddedServletContainerFactory;
 import org.springframework.context.annotation.Bean;
-import org.springframework.context.annotation.ConditionContext;
-import org.springframework.context.annotation.Conditional;
 import org.springframework.context.annotation.Configuration;
 import org.springframework.context.annotation.Import;
 import org.springframework.context.annotation.ImportBeanDefinitionRegistrar;
 import org.springframework.core.Ordered;
 import org.springframework.core.annotation.Order;
-import org.springframework.core.type.AnnotatedTypeMetadata;
 import org.springframework.core.type.AnnotationMetadata;
-import org.springframework.web.servlet.DispatcherServlet;
 
 /**
  * {@link EnableAutoConfiguration Auto-configuration} for an embedded servlet containers.
@@ -64,26 +56,6 @@ import org.springframework.web.servlet.DispatcherServlet;
 @Import(EmbeddedServletContainerCustomizerBeanPostProcessorRegistrar.class)
 public class EmbeddedServletContainerAutoConfiguration {
 
-	/*
-	 * The bean name for a DispatcherServlet that will be mapped to the root URL "/"
-	 */
-	public static final String DEFAULT_DISPATCHER_SERVLET_BEAN_NAME = "dispatcherServlet";
-
-	/**
-	 * Add the {@link DispatcherServlet} unless the user has defined their own
-	 * {@link ServletContextInitializer}s.
-	 */
-	@ConditionalOnClass(DispatcherServlet.class)
-	public static class DispatcherServletConfiguration {
-
-		@Bean(name = DEFAULT_DISPATCHER_SERVLET_BEAN_NAME)
-		@Conditional(DefaultServletCondition.class)
-		public DispatcherServlet dispatcherServlet() {
-			return new DispatcherServlet();
-		}
-
-	}
-
 	/**
 	 * Nested configuration for if Tomcat is being used.
 	 */
@@ -146,25 +118,4 @@ public class EmbeddedServletContainerAutoConfiguration {
 		}
 	}
 
-	private static class DefaultServletCondition extends SpringBootCondition {
-
-		@Override
-		public Outcome getMatchOutcome(ConditionContext context,
-				AnnotatedTypeMetadata metadata) {
-
-			ConfigurableListableBeanFactory beanFactory = context.getBeanFactory();
-			String[] beans = beanFactory.getBeanNamesForType(DispatcherServlet.class,
-					false, false);
-			if (beans.length == 0) {
-				return Outcome.match("no DispatcherServlet found");
-			}
-			if (Arrays.asList(beans).contains(DEFAULT_DISPATCHER_SERVLET_BEAN_NAME)) {
-				return Outcome.noMatch("found DispatcherServlet named "
-						+ DEFAULT_DISPATCHER_SERVLET_BEAN_NAME);
-			}
-			return Outcome.match("multiple DispatcherServlets found and none is named "
-					+ DEFAULT_DISPATCHER_SERVLET_BEAN_NAME);
-		}
-	}
-
 }

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

@@ -71,7 +71,7 @@ import org.springframework.web.servlet.view.InternalResourceViewResolver;
 		WebMvcConfigurerAdapter.class })
 @ConditionalOnMissingBean(WebMvcConfigurationSupport.class)
 @Order(Ordered.HIGHEST_PRECEDENCE + 10)
-@AutoConfigureAfter(EmbeddedServletContainerAutoConfiguration.class)
+@AutoConfigureAfter(DispatcherServletAutoConfiguration.class)
 public class WebMvcAutoConfiguration {
 
 	private static final String[] SERVLET_RESOURCE_LOCATIONS = { "/" };

spring-boot-autoconfigure/src/main/resources/META-INF/spring.factories

@@ -14,6 +14,7 @@ org.springframework.boot.autoconfigure.orm.jpa.HibernateJpaAutoConfiguration,\
 org.springframework.boot.autoconfigure.reactor.ReactorAutoConfiguration,\
 org.springframework.boot.autoconfigure.thymeleaf.ThymeleafAutoConfiguration,\
 org.springframework.boot.autoconfigure.web.EmbeddedServletContainerAutoConfiguration,\
+org.springframework.boot.autoconfigure.web.DispatcherServletAutoConfiguration,\
 org.springframework.boot.autoconfigure.web.ServerPropertiesAutoConfiguration,\
 org.springframework.boot.autoconfigure.web.MultipartAutoConfiguration,\
 org.springframework.boot.autoconfigure.web.WebMvcAutoConfiguration,\

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

@@ -49,7 +49,8 @@ public class EmbeddedServletContainerAutoConfigurationTests {
 	public void createFromConfigClass() throws Exception {
 		this.context = new AnnotationConfigEmbeddedWebApplicationContext(
 				EmbeddedContainerConfiguration.class,
-				EmbeddedServletContainerAutoConfiguration.class);
+				EmbeddedServletContainerAutoConfiguration.class,
+				DispatcherServletAutoConfiguration.class);
 		verifyContext();
 	}
 
@@ -58,7 +59,8 @@ public class EmbeddedServletContainerAutoConfigurationTests {
 		this.context = new AnnotationConfigEmbeddedWebApplicationContext(
 				DispatcherServletConfiguration.class,
 				EmbeddedContainerConfiguration.class,
-				EmbeddedServletContainerAutoConfiguration.class);
+				EmbeddedServletContainerAutoConfiguration.class,
+				DispatcherServletAutoConfiguration.class);
 		verifyContext();
 	}
 
@@ -66,7 +68,8 @@ public class EmbeddedServletContainerAutoConfigurationTests {
 	public void contextAlreadyHasDispatcherServlet() throws Exception {
 		this.context = new AnnotationConfigEmbeddedWebApplicationContext(
 				SpringServletConfiguration.class, EmbeddedContainerConfiguration.class,
-				EmbeddedServletContainerAutoConfiguration.class);
+				EmbeddedServletContainerAutoConfiguration.class,
+				DispatcherServletAutoConfiguration.class);
 		verifyContext();
 		assertEquals(2, this.context.getBeanNamesForType(DispatcherServlet.class).length);
 	}
@@ -76,7 +79,8 @@ public class EmbeddedServletContainerAutoConfigurationTests {
 		this.context = new AnnotationConfigEmbeddedWebApplicationContext(
 				EmbeddedContainerConfiguration.class,
 				EnsureContainerHasNoServletContext.class,
-				EmbeddedServletContainerAutoConfiguration.class);
+				EmbeddedServletContainerAutoConfiguration.class,
+				DispatcherServletAutoConfiguration.class);
 		verifyContext();
 	}
 
@@ -85,17 +89,17 @@ public class EmbeddedServletContainerAutoConfigurationTests {
 		this.context = new AnnotationConfigEmbeddedWebApplicationContext(
 				EmbeddedContainerConfiguration.class,
 				CallbackEmbeddedContainerCustomizer.class,
-				EmbeddedServletContainerAutoConfiguration.class);
+				EmbeddedServletContainerAutoConfiguration.class,
+				DispatcherServletAutoConfiguration.class);
 		verifyContext();
 		assertEquals(9000, getContainerFactory().getPort());
 	}
 
 	private void verifyContext() {
 		MockEmbeddedServletContainerFactory containerFactory = getContainerFactory();
-		Servlet servlet = this.context
-				.getBean(
-						EmbeddedServletContainerAutoConfiguration.DEFAULT_DISPATCHER_SERVLET_BEAN_NAME,
-						Servlet.class);
+		Servlet servlet = this.context.getBean(
+				DispatcherServletAutoConfiguration.DEFAULT_DISPATCHER_SERVLET_BEAN_NAME,
+				Servlet.class);
 		verify(containerFactory.getServletContext()).addServlet("dispatcherServlet",
 				servlet);
 	}

spring-boot/src/main/java/org/springframework/boot/context/embedded/EmbeddedWebApplicationContext.java

@@ -298,11 +298,17 @@ public class EmbeddedWebApplicationContext extends GenericWebApplicationContext
 	 * @param servletContext the operational servlet context
 	 */
 	protected void prepareEmbeddedWebApplicationContext(ServletContext servletContext) {
-		if (servletContext
-				.getAttribute(WebApplicationContext.ROOT_WEB_APPLICATION_CONTEXT_ATTRIBUTE) != null) {
-			throw new IllegalStateException(
-					"Cannot initialize context because there is already a root application context present - "
-							+ "check whether you have multiple ServletContextInitializer!");
+		Object rootContext = servletContext
+				.getAttribute(WebApplicationContext.ROOT_WEB_APPLICATION_CONTEXT_ATTRIBUTE);
+		if (rootContext != null) {
+			if (rootContext == this) {
+				throw new IllegalStateException(
+						"Cannot initialize context because there is already a root application context present - "
+								+ "check whether you have multiple ServletContextInitializers!");
+			}
+			else {
+				return;
+			}
 		}
 		Log logger = LogFactory.getLog(ContextLoader.class);
 		servletContext.log("Initializing Spring embedded WebApplicationContext");