Limit Servlet Listener registration

Limit Servlet Listener registration to the specific supported types.

Issue: #54112999

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

@@ -258,7 +258,8 @@ 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)) {
+			if (ServletListenerRegistrationBean.isSupportedType(listener)
+					&& !filterRegistrations.contains(listener)) {
 				ServletListenerRegistrationBean<EventListener> registration = new ServletListenerRegistrationBean<EventListener>(
 						listener);
 				registration.setName(name);

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

@@ -25,12 +25,12 @@ import org.springframework.core.Conventions;
 import org.springframework.util.Assert;
 
 /**
- * Base class for {@link ServletRegistrationBean servlet} and
+ * Base class for Servlet 3.0+ based registration beans.
- * {@link FilterRegistrationBean filter} registration beans.
  * 
  * @author Phillip Webb
  * @see ServletRegistrationBean
  * @see FilterRegistrationBean
+ * @see ServletListenerRegistrationBean
  */
 public abstract class RegistrationBean implements ServletContextInitializer {
 

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

@@ -16,31 +16,82 @@
 
 package org.springframework.boot.context.embedded;
 
+import java.util.Collections;
 import java.util.EventListener;
+import java.util.HashSet;
+import java.util.Set;
 
 import javax.servlet.ServletContext;
+import javax.servlet.ServletContextAttributeListener;
+import javax.servlet.ServletContextListener;
 import javax.servlet.ServletException;
+import javax.servlet.ServletRequestAttributeListener;
+import javax.servlet.ServletRequestListener;
+import javax.servlet.http.HttpSessionAttributeListener;
+import javax.servlet.http.HttpSessionListener;
+
+import org.springframework.util.Assert;
+import org.springframework.util.ClassUtils;
 
 /**
+ * A {@link ServletContextInitializer} to register {@link EventListener}s in a Servlet
+ * 3.0+ container. Similar to the {@link ServletContext#addListener(EventListener)
+ * registration} features provided by {@link ServletContext} but with a Spring Bean
+ * friendly design.
+ * 
+ * This bean can be used to register the following types of listener:
+ * <ul>
+ * <li>{@link ServletContextAttributeListener}</li>
+ * <li>{@link ServletRequestListener}</li>
+ * <li>{@link ServletRequestAttributeListener}</li>
+ * <li>{@link HttpSessionAttributeListener}</li>
+ * <li>{@link HttpSessionListener}</li>
+ * <li>{@link ServletContextListener}</li>
+ * </ul>
  * @author Dave Syer
+ * @author Phillip Webb
+ * @param <T> the type of listener
  */
 public class ServletListenerRegistrationBean<T extends EventListener> extends
 		RegistrationBean {
 
+	private static final Set<Class<?>> SUPPORTED_TYPES;
+	static {
+		Set<Class<?>> types = new HashSet<Class<?>>();
+		types.add(ServletContextAttributeListener.class);
+		types.add(ServletRequestListener.class);
+		types.add(ServletRequestAttributeListener.class);
+		types.add(HttpSessionAttributeListener.class);
+		types.add(HttpSessionListener.class);
+		types.add(ServletContextListener.class);
+		SUPPORTED_TYPES = Collections.unmodifiableSet(types);
+	}
+
 	private T listener;
 
 	/**
+	 * Create a new {@link ServletListenerRegistrationBean} instance.
+	 */
+	public ServletListenerRegistrationBean() {
+	}
+
+	/**
+	 * Create a new {@link ServletListenerRegistrationBean} instance.
 	 * @param listener the listener to register
 	 */
 	public ServletListenerRegistrationBean(T listener) {
-		super();
+		Assert.notNull(listener, "Listener must not be null");
+		Assert.isTrue(isSupportedType(listener), "EventLisener is not a supported type");
 		this.listener = listener;
 	}
 
 	/**
+	 * Set the listener that will be registered.
 	 * @param listener the listener to register
 	 */
 	public void setListener(T listener) {
+		Assert.notNull(listener, "Listener must not be null");
+		Assert.isTrue(isSupportedType(listener), "EventLisener is not a supported type");
 		this.listener = listener;
 	}
 
@@ -53,4 +104,18 @@ public class ServletListenerRegistrationBean<T extends EventListener> extends
 		return this.listener;
 	}
 
+	/**
+	 * Returns {@code true} if the specified listener is one of the supported types.
+	 * @param listener the listener to test
+	 * @return if the listener is of a supported type
+	 */
+	public static boolean isSupportedType(EventListener listener) {
+		for (Class<?> type : SUPPORTED_TYPES) {
+			if (ClassUtils.isAssignableValue(type, listener)) {
+				return true;
+			}
+		}
+		return false;
+	}
+
 }

spring-boot/src/test/java/org/springframework/boot/context/initializer/ConfigFileApplicationContextInitializerTests.java

@@ -20,7 +20,6 @@ import java.util.HashMap;
 import java.util.Map;
 
 import org.junit.Test;
-import org.springframework.boot.context.initializer.ConfigFileApplicationContextInitializer;
 import org.springframework.context.support.StaticApplicationContext;
 import org.springframework.core.env.MapPropertySource;
 import org.springframework.core.env.SimpleCommandLinePropertySource;
@@ -132,4 +131,9 @@ public class ConfigFileApplicationContextInitializerTests {
 		assertThat(property, equalTo("fromspecificlocation"));
 	}
 
+	@Test
+	public void defaultApplicationProperties() throws Exception {
+
+	}
+
 }