Allow consolidating config in root context with Java

Issue: SPR-11357
(backported from 4.0.1)

Author: jhoeller

spring-webmvc/src/main/java/org/springframework/web/servlet/support/AbstractAnnotationConfigDispatcherServletInitializer.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2012 the original author or authors.
+ * Copyright 2002-2014 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.
@@ -16,7 +16,6 @@
 
 package org.springframework.web.servlet.support;
 
-import org.springframework.util.Assert;
 import org.springframework.util.ObjectUtils;
 import org.springframework.web.context.WebApplicationContext;
 import org.springframework.web.context.support.AnnotationConfigWebApplicationContext;
@@ -28,8 +27,8 @@
  * configured with annotated classes, e.g. Spring's {@link
  * org.springframework.context.annotation.Configuration @Configuration} classes.
  *
- * <p>Concrete implementations are required to implement {@link #getRootConfigClasses()},
- * {@link #getServletConfigClasses()}, as well as {@link #getServletMappings()}. Further
+ * <p>Concrete implementations are required to implement {@link #getRootConfigClasses()}
+ * and {@link #getServletConfigClasses()} as well as {@link #getServletMappings()}. Further
  * template and customization methods are provided by {@link
  * AbstractDispatcherServletInitializer}.
  *
@@ -48,11 +47,10 @@ public abstract class AbstractAnnotationConfigDispatcherServletInitializer
 	 */
 	@Override
 	protected WebApplicationContext createRootApplicationContext() {
-		Class<?>[] rootConfigClasses = this.getRootConfigClasses();
-		if (!ObjectUtils.isEmpty(rootConfigClasses)) {
-			AnnotationConfigWebApplicationContext rootAppContext =
-					new AnnotationConfigWebApplicationContext();
-			rootAppContext.register(rootConfigClasses);
+		Class<?>[] configClasses = getRootConfigClasses();
+		if (!ObjectUtils.isEmpty(configClasses)) {
+			AnnotationConfigWebApplicationContext rootAppContext = new AnnotationConfigWebApplicationContext();
+			rootAppContext.register(configClasses);
 			return rootAppContext;
 		}
 		else {
@@ -64,18 +62,14 @@ protected WebApplicationContext createRootApplicationContext() {
 	 * {@inheritDoc}
 	 * <p>This implementation creates an {@link AnnotationConfigWebApplicationContext},
 	 * providing it the annotated classes returned by {@link #getServletConfigClasses()}.
-	 * @throws IllegalArgumentException if {@link #getServletConfigClasses()} returns
-	 * empty or {@code null}
 	 */
 	@Override
 	protected WebApplicationContext createServletApplicationContext() {
-		AnnotationConfigWebApplicationContext servletAppContext =
-				new AnnotationConfigWebApplicationContext();
-		Class<?>[] servletConfigClasses = this.getServletConfigClasses();
-		Assert.notEmpty(servletConfigClasses,
-				"getServletConfigClasses() did not return any configuration classes");
-
-		servletAppContext.register(servletConfigClasses);
+		AnnotationConfigWebApplicationContext servletAppContext = new AnnotationConfigWebApplicationContext();
+		Class<?>[] configClasses = getServletConfigClasses();
+		if (!ObjectUtils.isEmpty(configClasses)) {
+			servletAppContext.register(configClasses);
+		}
 		return servletAppContext;
 	}
 

spring-webmvc/src/test/java/org/springframework/web/servlet/support/AnnotationConfigDispatcherServletInitializerTests.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2012 the original author or authors.
+ * Copyright 2002-2014 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.
@@ -16,33 +16,34 @@
 
 package org.springframework.web.servlet.support;
 
-import static org.junit.Assert.assertEquals;
-import static org.junit.Assert.assertFalse;
-import static org.junit.Assert.assertNotNull;
-import static org.junit.Assert.assertTrue;
-
 import java.util.Collections;
 import java.util.EnumSet;
+import java.util.EventListener;
 import java.util.LinkedHashMap;
 import java.util.Map;
-
 import javax.servlet.DispatcherType;
 import javax.servlet.Filter;
 import javax.servlet.FilterRegistration.Dynamic;
 import javax.servlet.Servlet;
+import javax.servlet.ServletContextEvent;
+import javax.servlet.ServletContextListener;
 import javax.servlet.ServletException;
 import javax.servlet.ServletRegistration;
 
 import org.junit.Before;
 import org.junit.Test;
+
 import org.springframework.context.annotation.Bean;
 import org.springframework.context.annotation.Configuration;
+import org.springframework.mock.web.test.MockServletConfig;
 import org.springframework.mock.web.test.MockServletContext;
 import org.springframework.web.context.WebApplicationContext;
 import org.springframework.web.context.support.AnnotationConfigWebApplicationContext;
 import org.springframework.web.filter.HiddenHttpMethodFilter;
 import org.springframework.web.servlet.DispatcherServlet;
 
+import static org.junit.Assert.*;
+
 /**
  * Test case for {@link AbstractAnnotationConfigDispatcherServletInitializer}.
  *
@@ -89,11 +90,11 @@ public void register() throws ServletException {
 		assertNotNull(servlets.get(SERVLET_NAME));
 
 		DispatcherServlet servlet = (DispatcherServlet) servlets.get(SERVLET_NAME);
-		WebApplicationContext dispatcherServletContext = servlet.getWebApplicationContext();
-		((AnnotationConfigWebApplicationContext) dispatcherServletContext).refresh();
+		WebApplicationContext wac = servlet.getWebApplicationContext();
+		((AnnotationConfigWebApplicationContext) wac).refresh();
 
-		assertTrue(dispatcherServletContext.containsBean("bean"));
-		assertTrue(dispatcherServletContext.getBean("bean") instanceof MyBean);
+		assertTrue(wac.containsBean("bean"));
+		assertTrue(wac.getBean("bean") instanceof MyBean);
 
 		assertEquals(1, servletRegistrations.size());
 		assertNotNull(servletRegistrations.get(SERVLET_NAME));
@@ -135,6 +136,32 @@ protected boolean isAsyncSupported() {
 				filterRegistration.getMappings().get(SERVLET_NAME));
 	}
 
+	// SPR-11357
+	@Test
+	public void rootContextOnly() throws ServletException {
+		initializer = new MyAnnotationConfigDispatcherServletInitializer() {
+			@Override
+			protected Class<?>[] getRootConfigClasses() {
+				return new Class<?>[] {MyConfiguration.class};
+			}
+			@Override
+			protected Class<?>[] getServletConfigClasses() {
+				return null;
+			}
+		};
+
+		initializer.onStartup(servletContext);
+
+		DispatcherServlet servlet = (DispatcherServlet) servlets.get(SERVLET_NAME);
+		servlet.init(new MockServletConfig(this.servletContext));
+
+		WebApplicationContext wac = servlet.getWebApplicationContext();
+		((AnnotationConfigWebApplicationContext) wac).refresh();
+
+		assertTrue(wac.containsBean("bean"));
+		assertTrue(wac.getBean("bean") instanceof MyBean);
+	}
+
 	@Test
 	public void noFilters() throws ServletException {
 		initializer = new MyAnnotationConfigDispatcherServletInitializer() {
@@ -152,6 +179,12 @@ protected Filter[] getServletFilters() {
 
 	private class MyMockServletContext extends MockServletContext {
 
+		public <T extends EventListener> void addListener(T t) {
+			if (t instanceof ServletContextListener) {
+				((ServletContextListener) t).contextInitialized(new ServletContextEvent(this));
+			}
+		}
+
 		@Override
 		public ServletRegistration.Dynamic addServlet(String servletName, Servlet servlet) {
 			servlets.put(servletName, servlet);
@@ -169,6 +202,7 @@ public Dynamic addFilter(String filterName, Filter filter) {
 		}
 	}
 
+
 	private static class MyAnnotationConfigDispatcherServletInitializer
 			extends AbstractAnnotationConfigDispatcherServletInitializer {
 
@@ -201,13 +235,13 @@ protected void customizeRegistration(ServletRegistration.Dynamic registration) {
 		protected Class<?>[] getRootConfigClasses() {
 			return null;
 		}
-
 	}
 
-	private static class MyBean {
 
+	private static class MyBean {
 	}
 
+
 	@Configuration
 	@SuppressWarnings("unused")
 	private static class MyConfiguration {
@@ -219,7 +253,6 @@ public MyConfiguration() {
 		public MyBean bean() {
 			return new MyBean();
 		}
-
 	}
 
 }