Restructure embedded web server packages

Rework `org.springframework.boot.context.embedded` to relocate classes
to `org.springframework.boot.web`. Packages are now organized around
the following areas:

Packages for shared concerns, for example the `WebServer` interface
to start/stop a server and the common configuration elements:
- org.springframework.boot.web.context
- org.springframework.boot.web.server

Servlet specific packages:
- org.springframework.boot.web.servlet.server
- org.springframework.boot.web.servlet.context
- org.springframework.boot.web.servlet.filter

Reactive specific packages:
- org.springframework.boot.web.reactive.context
- org.springframework.boot.web.reactive.server

Embedded server implementations (both reactive and servlet):
- org.springframework.boot.web.embedded

In addition:

- Rename `EmbeddedServletContainerFactory` to `ServletWebServerFactory`
  to align with the `ReactiveWebServerFactory`.
- Rename `EmbeddedWebApplicationContext` to
  `ServletWebServerApplicationContext` and
- Rename `EmbeddedReactiveWebApplicationContext` to
  `ReactiveWebServerApplicationContext`.
- Add checkstyle rules to restrict imports.
- Fixup all affected code to use the correct imports and local names.

Fixes spring-projectsgh-8532

Author: philwebb

spring-boot-actuator/src/main/java/org/springframework/boot/actuate/autoconfigure/EndpointWebMvcAutoConfiguration.java

@@ -45,17 +45,17 @@
 import org.springframework.boot.autoconfigure.data.rest.RepositoryRestMvcAutoConfiguration;
 import org.springframework.boot.autoconfigure.hateoas.HypermediaAutoConfiguration;
 import org.springframework.boot.autoconfigure.web.DispatcherServletAutoConfiguration;
-import org.springframework.boot.autoconfigure.web.EmbeddedServletContainerAutoConfiguration;
 import org.springframework.boot.autoconfigure.web.HttpMessageConvertersAutoConfiguration;
 import org.springframework.boot.autoconfigure.web.ServerProperties;
+import org.springframework.boot.autoconfigure.web.ServletWebServerFactoryAutoConfiguration;
 import org.springframework.boot.autoconfigure.web.WebMvcAutoConfiguration;
 import org.springframework.boot.bind.RelaxedPropertyResolver;
-import org.springframework.boot.context.embedded.AnnotationConfigEmbeddedWebApplicationContext;
-import org.springframework.boot.context.embedded.EmbeddedServletContainerFactory;
-import org.springframework.boot.context.embedded.EmbeddedWebApplicationContext;
 import org.springframework.boot.context.event.ApplicationFailedEvent;
 import org.springframework.boot.context.properties.EnableConfigurationProperties;
-import org.springframework.boot.web.filter.ApplicationContextHeaderFilter;
+import org.springframework.boot.web.servlet.context.AnnotationConfigServletWebServerApplicationContext;
+import org.springframework.boot.web.servlet.context.ServletWebServerApplicationContext;
+import org.springframework.boot.web.servlet.filter.ApplicationContextHeaderFilter;
+import org.springframework.boot.web.servlet.server.ServletWebServerFactory;
 import org.springframework.context.ApplicationContext;
 import org.springframework.context.ApplicationContextAware;
 import org.springframework.context.ApplicationEvent;
@@ -95,7 +95,7 @@
 @ConditionalOnWebApplication(type = Type.SERVLET)
 @EnableConfigurationProperties(ManagementServerProperties.class)
 @AutoConfigureAfter({ PropertyPlaceholderAutoConfiguration.class,
-		EmbeddedServletContainerAutoConfiguration.class, WebMvcAutoConfiguration.class,
+		ServletWebServerFactoryAutoConfiguration.class, WebMvcAutoConfiguration.class,
 		RepositoryRestMvcAutoConfiguration.class, HypermediaAutoConfiguration.class,
 		HttpMessageConvertersAutoConfiguration.class })
 public class EndpointWebMvcAutoConfiguration
@@ -138,13 +138,13 @@ public void afterSingletonsInstantiated() {
 					.get(this.applicationContext.getEnvironment());
 		}
 		if (managementPort == ManagementServerPort.DIFFERENT) {
-			if (this.applicationContext instanceof EmbeddedWebApplicationContext
-					&& ((EmbeddedWebApplicationContext) this.applicationContext)
-							.getEmbeddedWebServer() != null) {
+			if (this.applicationContext instanceof ServletWebServerApplicationContext
+					&& ((ServletWebServerApplicationContext) this.applicationContext)
+							.getWebServer() != null) {
 				createChildManagementContext();
 			}
 			else {
-				logger.warn("Could not start embedded management container on "
+				logger.warn("Could not start management web server on "
 						+ "different port (management endpoints are still available "
 						+ "through JMX)");
 			}
@@ -166,49 +166,48 @@ public void afterSingletonsInstantiated() {
 	}
 
 	private void createChildManagementContext() {
-		AnnotationConfigEmbeddedWebApplicationContext childContext = new AnnotationConfigEmbeddedWebApplicationContext();
+		AnnotationConfigServletWebServerApplicationContext childContext = new AnnotationConfigServletWebServerApplicationContext();
 		childContext.setParent(this.applicationContext);
 		childContext.setNamespace("management");
 		childContext.setId(this.applicationContext.getId() + ":management");
 		childContext.setClassLoader(this.applicationContext.getClassLoader());
 		childContext.register(EndpointWebMvcChildContextConfiguration.class,
 				PropertyPlaceholderAutoConfiguration.class,
-				EmbeddedServletContainerAutoConfiguration.class,
+				ServletWebServerFactoryAutoConfiguration.class,
 				DispatcherServletAutoConfiguration.class);
-		registerEmbeddedServletContainerFactory(childContext);
+		registerServletWebServerFactory(childContext);
 		CloseManagementContextListener.addIfPossible(this.applicationContext,
 				childContext);
 		childContext.refresh();
 		managementContextResolver().setApplicationContext(childContext);
 	}
 
-	private void registerEmbeddedServletContainerFactory(
-			AnnotationConfigEmbeddedWebApplicationContext childContext) {
+	private void registerServletWebServerFactory(
+			AnnotationConfigServletWebServerApplicationContext childContext) {
 		try {
 			ConfigurableListableBeanFactory beanFactory = childContext.getBeanFactory();
 			if (beanFactory instanceof BeanDefinitionRegistry) {
 				BeanDefinitionRegistry registry = (BeanDefinitionRegistry) beanFactory;
-				registry.registerBeanDefinition("embeddedServletContainerFactory",
-						new RootBeanDefinition(
-								determineEmbeddedServletContainerFactoryClass()));
+				registry.registerBeanDefinition("ServletWebServerFactory",
+						new RootBeanDefinition(determineServletWebServerFactoryClass()));
 			}
 		}
 		catch (NoSuchBeanDefinitionException ex) {
 			// Ignore and assume auto-configuration
 		}
 	}
 
-	private Class<?> determineEmbeddedServletContainerFactoryClass()
+	private Class<?> determineServletWebServerFactoryClass()
 			throws NoSuchBeanDefinitionException {
-		Class<?> servletContainerFactoryClass = this.applicationContext
-				.getBean(EmbeddedServletContainerFactory.class).getClass();
-		if (cannotBeInstantiated(servletContainerFactoryClass)) {
-			throw new FatalBeanException("EmbeddedServletContainerFactory implementation "
-					+ servletContainerFactoryClass.getName() + " cannot be instantiated. "
+		Class<?> factoryClass = this.applicationContext
+				.getBean(ServletWebServerFactory.class).getClass();
+		if (cannotBeInstantiated(factoryClass)) {
+			throw new FatalBeanException("ServletWebServerFactory implementation "
+					+ factoryClass.getName() + " cannot be instantiated. "
 					+ "To allow a separate management port to be used, a top-level class "
 					+ "or static inner class should be used instead");
 		}
-		return servletContainerFactoryClass;
+		return factoryClass;
 	}
 
 	private boolean cannotBeInstantiated(Class<?> clazz) {

spring-boot-actuator/src/main/java/org/springframework/boot/actuate/autoconfigure/EndpointWebMvcChildContextConfiguration.java

@@ -40,17 +40,17 @@
 import org.springframework.boot.autoconfigure.condition.ConditionalOnClass;
 import org.springframework.boot.autoconfigure.condition.SearchStrategy;
 import org.springframework.boot.autoconfigure.hateoas.HypermediaHttpMessageConverterConfiguration;
-import org.springframework.boot.autoconfigure.web.DefaultServletContainerCustomizer;
+import org.springframework.boot.autoconfigure.web.DefaultServletWebServerFactoryCustomizer;
 import org.springframework.boot.autoconfigure.web.DispatcherServletAutoConfiguration;
 import org.springframework.boot.autoconfigure.web.ErrorAttributes;
 import org.springframework.boot.autoconfigure.web.ServerProperties;
-import org.springframework.boot.context.embedded.ConfigurableEmbeddedServletContainer;
-import org.springframework.boot.context.embedded.EmbeddedServletContainerCustomizer;
-import org.springframework.boot.context.embedded.EmbeddedServletContainerFactory;
-import org.springframework.boot.context.embedded.EmbeddedWebServer;
-import org.springframework.boot.context.embedded.tomcat.TomcatEmbeddedServletContainerFactory;
-import org.springframework.boot.context.embedded.undertow.UndertowEmbeddedServletContainerFactory;
-import org.springframework.boot.web.servlet.ErrorPage;
+import org.springframework.boot.web.embedded.tomcat.TomcatServletWebServerFactory;
+import org.springframework.boot.web.embedded.undertow.UndertowServletWebServerFactory;
+import org.springframework.boot.web.server.ErrorPage;
+import org.springframework.boot.web.server.WebServer;
+import org.springframework.boot.web.servlet.server.ConfigurableServletWebServerFactory;
+import org.springframework.boot.web.servlet.server.ServletWebServerFactory;
+import org.springframework.boot.web.servlet.server.ServletWebServerFactoryCustomizer;
 import org.springframework.context.annotation.Bean;
 import org.springframework.context.annotation.Configuration;
 import org.springframework.context.annotation.Import;
@@ -69,7 +69,7 @@
 
 /**
  * Configuration triggered from {@link EndpointWebMvcAutoConfiguration} when a new
- * {@link EmbeddedWebServer} running on a different port is required.
+ * {@link WebServer} running on a different port is required.
  *
  * @author Dave Syer
  * @author Stephane Nicoll
@@ -109,8 +109,8 @@ public CompositeHandlerExceptionResolver compositeHandlerExceptionResolver() {
 	}
 
 	@Bean
-	public ServerCustomization serverCustomization() {
-		return new ServerCustomization();
+	public ServerFactoryCustomization serverCustomization() {
+		return new ServerFactoryCustomization();
 	}
 
 	@Bean
@@ -171,51 +171,51 @@ static class HypermediaConfiguration {
 
 	}
 
-	static class ServerCustomization
-			implements EmbeddedServletContainerCustomizer, Ordered {
+	static class ServerFactoryCustomization
+			implements ServletWebServerFactoryCustomizer, Ordered {
 
 		@Autowired
 		private ListableBeanFactory beanFactory;
 
-		// This needs to be lazily initialized because EmbeddedServletContainerCustomizer
+		// This needs to be lazily initialized because web server customizer
 		// instances get their callback very early in the context lifecycle.
 		private ManagementServerProperties managementServerProperties;
 
 		private ServerProperties server;
 
-		private DefaultServletContainerCustomizer serverCustomizer;
+		private DefaultServletWebServerFactoryCustomizer serverCustomizer;
 
 		@Override
 		public int getOrder() {
 			return 0;
 		}
 
 		@Override
-		public void customize(ConfigurableEmbeddedServletContainer container) {
+		public void customize(ConfigurableServletWebServerFactory webServerFactory) {
 			if (this.managementServerProperties == null) {
 				this.managementServerProperties = BeanFactoryUtils
 						.beanOfTypeIncludingAncestors(this.beanFactory,
 								ManagementServerProperties.class);
 				this.server = BeanFactoryUtils.beanOfTypeIncludingAncestors(
 						this.beanFactory, ServerProperties.class);
 				this.serverCustomizer = BeanFactoryUtils.beanOfTypeIncludingAncestors(
-						this.beanFactory, DefaultServletContainerCustomizer.class);
+						this.beanFactory, DefaultServletWebServerFactoryCustomizer.class);
 			}
 			// Customize as per the parent context first (so e.g. the access logs go to
 			// the same place)
-			this.serverCustomizer.customize(container);
+			this.serverCustomizer.customize(webServerFactory);
 			// Then reset the error pages
-			container.setErrorPages(Collections.<ErrorPage>emptySet());
+			webServerFactory.setErrorPages(Collections.<ErrorPage>emptySet());
 			// and the context path
-			container.setContextPath("");
+			webServerFactory.setContextPath("");
 			// and add the management-specific bits
-			container.setPort(this.managementServerProperties.getPort());
+			webServerFactory.setPort(this.managementServerProperties.getPort());
 			if (this.managementServerProperties.getSsl() != null) {
-				container.setSsl(this.managementServerProperties.getSsl());
+				webServerFactory.setSsl(this.managementServerProperties.getSsl());
 			}
-			container.setServerHeader(this.server.getServerHeader());
-			container.setAddress(this.managementServerProperties.getAddress());
-			container.addErrorPages(new ErrorPage(this.server.getError().getPath()));
+			webServerFactory.setServerHeader(this.server.getServerHeader());
+			webServerFactory.setAddress(this.managementServerProperties.getAddress());
+			webServerFactory.addErrorPages(new ErrorPage(this.server.getError().getPath()));
 		}
 
 	}
@@ -343,8 +343,8 @@ public ModelAndView resolveException(HttpServletRequest request,
 
 	}
 
-	static abstract class AccessLogCustomizer<T extends EmbeddedServletContainerFactory>
-			implements EmbeddedServletContainerCustomizer, Ordered {
+	static abstract class AccessLogCustomizer<T extends ServletWebServerFactory>
+			implements ServletWebServerFactoryCustomizer, Ordered {
 
 		private final Class<T> factoryClass;
 
@@ -362,35 +362,35 @@ public int getOrder() {
 		}
 
 		@Override
-		public void customize(ConfigurableEmbeddedServletContainer container) {
-			if (this.factoryClass.isInstance(container)) {
-				customize(this.factoryClass.cast(container));
+		public void customize(ConfigurableServletWebServerFactory serverFactory) {
+			if (this.factoryClass.isInstance(serverFactory)) {
+				customize(this.factoryClass.cast(serverFactory));
 			}
 		}
 
-		abstract void customize(T container);
+		abstract void customize(T webServerFactory);
 
 	}
 
 	static class TomcatAccessLogCustomizer
-			extends AccessLogCustomizer<TomcatEmbeddedServletContainerFactory> {
+			extends AccessLogCustomizer<TomcatServletWebServerFactory> {
 
 		TomcatAccessLogCustomizer() {
-			super(TomcatEmbeddedServletContainerFactory.class);
+			super(TomcatServletWebServerFactory.class);
 		}
 
 		@Override
-		public void customize(TomcatEmbeddedServletContainerFactory container) {
-			AccessLogValve accessLogValve = findAccessLogValve(container);
+		public void customize(TomcatServletWebServerFactory serverFactory) {
+			AccessLogValve accessLogValve = findAccessLogValve(serverFactory);
 			if (accessLogValve == null) {
 				return;
 			}
 			accessLogValve.setPrefix(customizePrefix(accessLogValve.getPrefix()));
 		}
 
 		private AccessLogValve findAccessLogValve(
-				TomcatEmbeddedServletContainerFactory container) {
-			for (Valve engineValve : container.getEngineValves()) {
+				TomcatServletWebServerFactory serverFactory) {
+			for (Valve engineValve : serverFactory.getEngineValves()) {
 				if (engineValve instanceof AccessLogValve) {
 					return (AccessLogValve) engineValve;
 				}
@@ -401,15 +401,15 @@ private AccessLogValve findAccessLogValve(
 	}
 
 	static class UndertowAccessLogCustomizer
-			extends AccessLogCustomizer<UndertowEmbeddedServletContainerFactory> {
+			extends AccessLogCustomizer<UndertowServletWebServerFactory> {
 
 		UndertowAccessLogCustomizer() {
-			super(UndertowEmbeddedServletContainerFactory.class);
+			super(UndertowServletWebServerFactory.class);
 		}
 
 		@Override
-		public void customize(UndertowEmbeddedServletContainerFactory container) {
-			container.setAccessLogPrefix(customizePrefix(container.getAccessLogPrefix()));
+		public void customize(UndertowServletWebServerFactory serverFactory) {
+			serverFactory.setAccessLogPrefix(customizePrefix(serverFactory.getAccessLogPrefix()));
 		}
 
 	}

spring-boot-actuator/src/main/java/org/springframework/boot/actuate/autoconfigure/JolokiaAutoConfiguration.java

@@ -32,7 +32,7 @@
 import org.springframework.boot.autoconfigure.condition.ConditionalOnWebApplication;
 import org.springframework.boot.autoconfigure.condition.ConditionalOnWebApplication.Type;
 import org.springframework.boot.autoconfigure.condition.SpringBootCondition;
-import org.springframework.boot.autoconfigure.web.EmbeddedServletContainerAutoConfiguration;
+import org.springframework.boot.autoconfigure.web.ServletWebServerFactoryAutoConfiguration;
 import org.springframework.boot.bind.RelaxedPropertyResolver;
 import org.springframework.boot.context.properties.EnableConfigurationProperties;
 import org.springframework.context.annotation.Bean;
@@ -66,7 +66,7 @@
 @ConditionalOnClass({ AgentServlet.class, ServletWrappingController.class })
 @Conditional(JolokiaCondition.class)
 @AutoConfigureBefore(ManagementWebSecurityAutoConfiguration.class)
-@AutoConfigureAfter(EmbeddedServletContainerAutoConfiguration.class)
+@AutoConfigureAfter(ServletWebServerFactoryAutoConfiguration.class)
 @EnableConfigurationProperties(JolokiaProperties.class)
 public class JolokiaAutoConfiguration {
 

spring-boot-actuator/src/main/java/org/springframework/boot/actuate/autoconfigure/ManagementServerProperties.java

@@ -25,9 +25,9 @@
 import org.springframework.boot.autoconfigure.security.SecurityPrerequisite;
 import org.springframework.boot.autoconfigure.security.SecurityProperties;
 import org.springframework.boot.autoconfigure.web.ServerProperties;
-import org.springframework.boot.context.embedded.Ssl;
 import org.springframework.boot.context.properties.ConfigurationProperties;
 import org.springframework.boot.context.properties.NestedConfigurationProperty;
+import org.springframework.boot.web.server.Ssl;
 import org.springframework.util.Assert;
 import org.springframework.util.StringUtils;
 

spring-boot-actuator/src/main/java/org/springframework/boot/actuate/endpoint/TomcatPublicMetrics.java

@@ -28,9 +28,9 @@
 
 import org.springframework.beans.BeansException;
 import org.springframework.boot.actuate.metrics.Metric;
-import org.springframework.boot.context.embedded.EmbeddedWebApplicationContext;
-import org.springframework.boot.context.embedded.EmbeddedWebServer;
-import org.springframework.boot.context.embedded.tomcat.TomcatEmbeddedServletContainer;
+import org.springframework.boot.web.embedded.tomcat.TomcatWebServer;
+import org.springframework.boot.web.server.WebServer;
+import org.springframework.boot.web.servlet.context.ServletWebServerApplicationContext;
 import org.springframework.context.ApplicationContext;
 import org.springframework.context.ApplicationContextAware;
 
@@ -47,26 +47,26 @@ public class TomcatPublicMetrics implements PublicMetrics, ApplicationContextAwa
 
 	@Override
 	public Collection<Metric<?>> metrics() {
-		if (this.applicationContext instanceof EmbeddedWebApplicationContext) {
+		if (this.applicationContext instanceof ServletWebServerApplicationContext) {
 			Manager manager = getManager(
-					(EmbeddedWebApplicationContext) this.applicationContext);
+					(ServletWebServerApplicationContext) this.applicationContext);
 			if (manager != null) {
 				return metrics(manager);
 			}
 		}
 		return Collections.emptySet();
 	}
 
-	private Manager getManager(EmbeddedWebApplicationContext applicationContext) {
-		EmbeddedWebServer embeddedWebServer = applicationContext.getEmbeddedWebServer();
-		if (embeddedWebServer instanceof TomcatEmbeddedServletContainer) {
-			return getManager((TomcatEmbeddedServletContainer) embeddedWebServer);
+	private Manager getManager(ServletWebServerApplicationContext applicationContext) {
+		WebServer webServer = applicationContext.getWebServer();
+		if (webServer instanceof TomcatWebServer) {
+			return getManager((TomcatWebServer) webServer);
 		}
 		return null;
 	}
 
-	private Manager getManager(TomcatEmbeddedServletContainer servletContainer) {
-		for (Container container : servletContainer.getTomcat().getHost()
+	private Manager getManager(TomcatWebServer webServer) {
+		for (Container container : webServer.getTomcat().getHost()
 				.findChildren()) {
 			if (container instanceof Context) {
 				return ((Context) container).getManager();