Add ServletContextListener to embedded web app

* User can add @Bean of type EventListener (e.g.
ServletContextListener)

[Fixes #54112999] [bs-254]

spring-boot-samples/spring-boot-sample-tomcat/src/main/java/org/springframework/boot/sample/tomcat/SampleTomcatApplication.java

@@ -16,8 +16,14 @@
 
 package org.springframework.boot.sample.tomcat;
 
+import javax.servlet.ServletContextEvent;
+import javax.servlet.ServletContextListener;
+
+import org.apache.commons.logging.Log;
+import org.apache.commons.logging.LogFactory;
 import org.springframework.boot.SpringApplication;
 import org.springframework.boot.autoconfigure.EnableAutoConfiguration;
+import org.springframework.context.annotation.Bean;
 import org.springframework.context.annotation.ComponentScan;
 import org.springframework.context.annotation.Configuration;
 
@@ -26,8 +32,25 @@ import org.springframework.context.annotation.Configuration;
 @ComponentScan
 public class SampleTomcatApplication {
 
+	private static Log logger = LogFactory.getLog(SampleTomcatApplication.class);
+
 	public static void main(String[] args) throws Exception {
 		SpringApplication.run(SampleTomcatApplication.class, args);
 	}
 
+	@Bean
+	protected ServletContextListener listener() {
+		return new ServletContextListener() {
+			@Override
+			public void contextInitialized(ServletContextEvent sce) {
+				logger.info("ServletContext initialized");
+			}
+
+			@Override
+			public void contextDestroyed(ServletContextEvent sce) {
+				logger.info("ServletContext destroyed");
+			}
+		};
+	}
+
 }

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

@@ -20,6 +20,7 @@ import java.util.ArrayList;
 import java.util.Collection;
 import java.util.Collections;
 import java.util.Comparator;
+import java.util.EventListener;
 import java.util.LinkedHashSet;
 import java.util.List;
 import java.util.Map.Entry;
@@ -207,6 +208,7 @@ public class EmbeddedWebApplicationContext extends GenericWebApplicationContext
 		Set<ServletContextInitializer> initializers = new LinkedHashSet<ServletContextInitializer>();
 		Set<Servlet> servletRegistrations = new LinkedHashSet<Servlet>();
 		Set<Filter> filterRegistrations = new LinkedHashSet<Filter>();
+		Set<EventListener> listenerRegistrations = new LinkedHashSet<EventListener>();
 
 		for (Entry<String, ServletContextInitializer> initializerBean : getOrderedBeansOfType(ServletContextInitializer.class)) {
 			ServletContextInitializer initializer = initializerBean.getValue();
@@ -219,6 +221,11 @@ public class EmbeddedWebApplicationContext extends GenericWebApplicationContext
 				filterRegistrations.add(((FilterRegistrationBean) initializer)
 						.getFilter());
 			}
+			if (initializer instanceof ServletListenerRegistrationBean) {
+				listenerRegistrations
+						.add(((ServletListenerRegistrationBean<?>) initializer)
+								.getListener());
+			}
 		}
 
 		List<Entry<String, Servlet>> servletBeans = getOrderedBeansOfType(Servlet.class);
@@ -248,6 +255,17 @@ public class EmbeddedWebApplicationContext extends GenericWebApplicationContext
 			}
 		}
 
+		for (Entry<String, EventListener> listenerBean : getOrderedBeansOfType(EventListener.class)) {
+			String name = listenerBean.getKey();
+			EventListener listener = listenerBean.getValue();
+			if (!filterRegistrations.contains(listener)) {
+				ServletListenerRegistrationBean<EventListener> registration = new ServletListenerRegistrationBean<EventListener>(
+						listener);
+				registration.setName(name);
+				initializers.add(registration);
+			}
+		}
+
 		return initializers;
 	}
 

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

@@ -0,0 +1,56 @@
+/*
+ * 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.context.embedded;
+
+import java.util.EventListener;
+
+import javax.servlet.ServletContext;
+import javax.servlet.ServletException;
+
+/**
+ * @author Dave Syer
+ */
+public class ServletListenerRegistrationBean<T extends EventListener> extends
+		RegistrationBean {
+
+	private T listener;
+
+	/**
+	 * @param listener the listener to register
+	 */
+	public ServletListenerRegistrationBean(T listener) {
+		super();
+		this.listener = listener;
+	}
+
+	/**
+	 * @param listener the listener to register
+	 */
+	public void setListener(T listener) {
+		this.listener = listener;
+	}
+
+	@Override
+	public void onStartup(ServletContext servletContext) throws ServletException {
+		servletContext.addListener(this.listener);
+	}
+
+	public T getListener() {
+		return this.listener;
+	}
+
+}

spring-boot/src/test/java/org/springframework/boot/context/embedded/ServletListenerRegistrationBeanTests.java

@@ -0,0 +1,60 @@
+/*
+ * Copyright 2002-2013 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.context.embedded;
+
+import javax.servlet.ServletContext;
+import javax.servlet.ServletContextListener;
+
+import org.junit.Before;
+import org.junit.Rule;
+import org.junit.Test;
+import org.junit.rules.ExpectedException;
+import org.mockito.Mock;
+import org.mockito.Mockito;
+import org.mockito.MockitoAnnotations;
+
+import static org.mockito.Mockito.verify;
+
+/**
+ * Tests for {@link ServletListenerRegistrationBean}.
+ * 
+ * @author Dave Syer
+ */
+public class ServletListenerRegistrationBeanTests {
+
+	@Rule
+	public ExpectedException thrown = ExpectedException.none();
+
+	private ServletContextListener listener = Mockito.mock(ServletContextListener.class);
+
+	@Mock
+	private ServletContext servletContext;
+
+	@Before
+	public void setupMocks() {
+		MockitoAnnotations.initMocks(this);
+	}
+
+	@Test
+	public void startupWithDefaults() throws Exception {
+		ServletListenerRegistrationBean<ServletContextListener> bean = new ServletListenerRegistrationBean<ServletContextListener>(
+				this.listener);
+		bean.onStartup(this.servletContext);
+		verify(this.servletContext).addListener(this.listener);
+	}
+
+}