[bs-52] Added support for SpringApplication in a ServletContextInitializer

WAR applications should extend SpringServletInitializer to take advantage
of Servlet 3.0 initialization and SpringApplication context loading features.

[#48386505] [bs-52] Support for running "traditional" webapps in place

spring-bootstrap/src/main/java/org/springframework/bootstrap/SpringApplication.java

@@ -391,9 +391,8 @@ public class SpringApplication {
 	 * @param sources the sources to load
 	 */
 	protected void load(ApplicationContext context, Object[] sources) {
-		Assert.isInstanceOf(BeanDefinitionRegistry.class, context);
 		BeanDefinitionLoader loader = createBeanDefinitionLoader(
-				(BeanDefinitionRegistry) context, sources);
+				getBeanDefinitionRegistry(context), sources);
 		if (this.beanNameGenerator != null) {
 			loader.setBeanNameGenerator(this.beanNameGenerator);
 		}
@@ -406,6 +405,17 @@ public class SpringApplication {
 		loader.load();
 	}
 
+	/**
+	 * @param context the application context
+	 * @return the BeanDefinitionRegistry if it can be determined
+	 */
+	private BeanDefinitionRegistry getBeanDefinitionRegistry(ApplicationContext context) {
+		if (context instanceof BeanDefinitionRegistry) {
+			return (BeanDefinitionRegistry) context;
+		}
+		throw new IllegalStateException("Could not locate BeanDefinitionRegistry");
+	}
+
 	/**
 	 * Factory method used to create the {@link BeanDefinitionLoader}.
 	 * @param registry the bean definition registry

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

@@ -127,16 +127,25 @@ public class EmbeddedWebApplicationContext extends GenericWebApplicationContext
 	}
 
 	private synchronized void createAndStartEmbeddedServletContainer() {
-		if (this.embeddedServletContainer == null) {
+		if (this.embeddedServletContainer == null && getServletContext() == null) {
 			EmbeddedServletContainerFactory containerFactory = getEmbeddedServletContainerFactory();
 			this.embeddedServletContainer = containerFactory
 					.getEmbdeddedServletContainer(getServletContextInitializers());
-			WebApplicationContextUtils.registerWebApplicationScopes(getBeanFactory(),
-					getServletContext());
-			WebApplicationContextUtils.registerEnvironmentBeans(getBeanFactory(),
-					getServletContext());
-			initPropertySources();
+		} else if (getServletContext() != null) {
+			for (ServletContextInitializer initializer : getServletContextInitializers()) {
+				try {
+					initializer.onStartup(getServletContext());
+				} catch (ServletException e) {
+					throw new ApplicationContextException(
+							"Cannot initialize servlet context", e);
+				}
+			}
 		}
+		WebApplicationContextUtils.registerWebApplicationScopes(getBeanFactory(),
+				getServletContext());
+		WebApplicationContextUtils.registerEnvironmentBeans(getBeanFactory(),
+				getServletContext());
+		initPropertySources();
 	}
 
 	/**
@@ -339,4 +348,5 @@ public class EmbeddedWebApplicationContext extends GenericWebApplicationContext
 	public EmbeddedServletContainer getEmbeddedServletContainer() {
 		return this.embeddedServletContainer;
 	}
+
 }

spring-bootstrap/src/main/java/org/springframework/bootstrap/web/BootstrapServletInitializer.java

@@ -1,55 +0,0 @@
-package org.springframework.bootstrap.web;
-
-import javax.servlet.Filter;
-
-import org.springframework.util.ClassUtils;
-import org.springframework.web.WebApplicationInitializer;
-import org.springframework.web.filter.DelegatingFilterProxy;
-import org.springframework.web.servlet.FrameworkServlet;
-import org.springframework.web.servlet.support.AbstractAnnotationConfigDispatcherServletInitializer;
-
-/**
- * <p>
- * A handy opinionated {@link WebApplicationInitializer} for applications that only have
- * one Spring servlet, and no more than a single filter (which itself is only enabled when
- * Spring Security is detected). If your application is more complicated consider using
- * one of the other WebApplicationInitializers.
- * <p>
- * 
- * <p>
- * Note that a WebApplicationInitializer is only needed if you are building a war file and
- * deploying it. If you prefer to run an embedded container (we do) then you won't need
- * this at all.
- * </p>
- * 
- * @author Dave Syer
- * 
- */
-public abstract class BootstrapServletInitializer extends
-		AbstractAnnotationConfigDispatcherServletInitializer {
-
-	@Override
-	protected Class<?>[] getRootConfigClasses() {
-		return null;
-	}
-
-	@Override
-	protected String[] getServletMappings() {
-		return new String[] { "/" };
-	}
-
-	@Override
-	protected Filter[] getServletFilters() {
-		if (ClassUtils.isPresent(
-				"org.springframework.security.config.annotation.web.EnableWebSecurity",
-				null)) {
-			DelegatingFilterProxy filter = new DelegatingFilterProxy(
-					"springSecurityFilterChain");
-			filter.setContextAttribute(FrameworkServlet.SERVLET_CONTEXT_PREFIX
-					+ "dispatcher");
-			return new Filter[] { filter };
-		}
-		return new Filter[0];
-	}
-
-}

spring-bootstrap/src/main/java/org/springframework/bootstrap/web/SpringServletInitializer.java

@@ -0,0 +1,77 @@
+package org.springframework.bootstrap.web;
+
+import javax.servlet.ServletContext;
+import javax.servlet.ServletContextEvent;
+import javax.servlet.ServletException;
+
+import org.apache.commons.logging.Log;
+import org.apache.commons.logging.LogFactory;
+import org.springframework.bootstrap.SpringApplication;
+import org.springframework.bootstrap.context.embedded.AnnotationConfigEmbeddedWebApplicationContext;
+import org.springframework.context.ApplicationContext;
+import org.springframework.web.WebApplicationInitializer;
+import org.springframework.web.context.ContextLoaderListener;
+import org.springframework.web.context.WebApplicationContext;
+
+/**
+ * <p>
+ * A handy opinionated {@link WebApplicationInitializer} for applications that only have
+ * one Spring servlet, and no more than a single filter (which itself is only enabled when
+ * Spring Security is detected). If your application is more complicated consider using
+ * one of the other WebApplicationInitializers.
+ * <p>
+ * 
+ * <p>
+ * Note that a WebApplicationInitializer is only needed if you are building a war file and
+ * deploying it. If you prefer to run an embedded container (we do) then you won't need
+ * this at all.
+ * </p>
+ * 
+ * @author Dave Syer
+ * 
+ */
+public abstract class SpringServletInitializer implements WebApplicationInitializer {
+
+	/** Logger available to subclasses. */
+	protected final Log logger = LogFactory.getLog(getClass());
+
+	public void onStartup(ServletContext servletContext) throws ServletException {
+		WebApplicationContext rootAppContext = this
+				.createRootApplicationContext(servletContext);
+		if (rootAppContext != null) {
+			servletContext.addListener(new ContextLoaderListener(rootAppContext) {
+				@Override
+				public void contextInitialized(ServletContextEvent event) {
+					// no-op because the application context is already initialized
+				}
+			});
+		} else {
+			this.logger
+					.debug("No ContextLoaderListener registered, as "
+							+ "createRootApplicationContext() did not return an application context");
+		}
+	}
+
+	protected WebApplicationContext createRootApplicationContext(
+			ServletContext servletContext) {
+		ApplicationContext parent = null;
+		Object object = servletContext
+				.getAttribute(WebApplicationContext.ROOT_WEB_APPLICATION_CONTEXT_ATTRIBUTE);
+		if (object != null && object instanceof ApplicationContext) {
+			this.logger.info("Root context already created (using as parent).");
+			parent = (ApplicationContext) object;
+			servletContext.setAttribute(
+					WebApplicationContext.ROOT_WEB_APPLICATION_CONTEXT_ATTRIBUTE, null);
+		}
+		SpringApplication application = new SpringApplication(
+				(Object[]) getConfigClasses());
+		AnnotationConfigEmbeddedWebApplicationContext context = new AnnotationConfigEmbeddedWebApplicationContext();
+		context.setParent(parent);
+		context.setServletContext(servletContext);
+		application.setApplicationContext(context);
+		return (WebApplicationContext) application.run();
+	}
+
+	protected abstract Class<?>[] getConfigClasses();
+
+}