Multicaster support for events with null source

Update `AbstractApplicationEventMulticaster` to support `EventObjects`
with a null source (which can happen if they have been serialized).

Issue: SPR-10945
(cherry picked from commit b0ff834)

Author: Phillip Webb

spring-context/src/main/java/org/springframework/context/event/AbstractApplicationEventMulticaster.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2012 the original author or authors.
+ * 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.
@@ -28,6 +28,7 @@
 import org.springframework.context.ApplicationEvent;
 import org.springframework.context.ApplicationListener;
 import org.springframework.core.OrderComparator;
+import org.springframework.util.ObjectUtils;
 
 /**
  * Abstract implementation of the {@link ApplicationEventMulticaster} interface,
@@ -128,7 +129,8 @@ protected Collection<ApplicationListener> getApplicationListeners() {
 	 */
 	protected Collection<ApplicationListener> getApplicationListeners(ApplicationEvent event) {
 		Class<? extends ApplicationEvent> eventType = event.getClass();
-		Class sourceType = event.getSource().getClass();
+		Object source = event.getSource();
+		Class sourceType = (source == null ? null : source.getClass());
 		ListenerCacheKey cacheKey = new ListenerCacheKey(eventType, sourceType);
 		ListenerRetriever retriever = this.retrieverCache.get(cacheKey);
 		if (retriever != null) {
@@ -206,12 +208,14 @@ public boolean equals(Object other) {
 				return true;
 			}
 			ListenerCacheKey otherKey = (ListenerCacheKey) other;
-			return (this.eventType.equals(otherKey.eventType) && this.sourceType.equals(otherKey.sourceType));
+			return ObjectUtils.nullSafeEquals(this.eventType, otherKey.eventType)
+					&& ObjectUtils.nullSafeEquals(this.sourceType, otherKey.sourceType);
 		}
 
 		@Override
 		public int hashCode() {
-			return this.eventType.hashCode() * 29 + this.sourceType.hashCode();
+			return ObjectUtils.nullSafeHashCode(this.eventType) * 29
+					+ ObjectUtils.nullSafeHashCode(this.sourceType);
 		}
 	}
 

spring-context/src/main/java/org/springframework/context/event/SourceFilteringListener.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2012 the original author or authors.
+ * 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.
@@ -74,7 +74,7 @@ public boolean supportsEventType(Class<? extends ApplicationEvent> eventType) {
 	}
 
 	public boolean supportsSourceType(Class<?> sourceType) {
-		return sourceType.isInstance(this.source);
+		return (sourceType != null && sourceType.isInstance(this.source));
 	}
 
 	public int getOrder() {

spring-context/src/test/java/org/springframework/context/AbstractApplicationContextTests.java

@@ -16,8 +16,13 @@
 
 package org.springframework.context;
 
+import java.io.ByteArrayInputStream;
+import java.io.ByteArrayOutputStream;
+import java.io.ObjectInputStream;
+import java.io.ObjectOutputStream;
 import java.util.Locale;
 
+import org.junit.Test;
 import org.springframework.beans.factory.BeanFactory;
 import org.springframework.beans.factory.xml.AbstractListableBeanFactoryTests;
 import org.springframework.tests.sample.beans.LifecycleBean;
@@ -129,11 +134,29 @@ public void testMessageSource() throws NoSuchMessageException {
 	}
 
 	public void testEvents() throws Exception {
+		doTestEvents(this.listener, this.parentListener, new MyEvent(this));
+	}
+
+	@Test
+	public void testEventsWithNoSource() throws Exception {
+		// See SPR-10945 Serialized events result in a null source
+		MyEvent event = new MyEvent(this);
+		ByteArrayOutputStream bos = new ByteArrayOutputStream();
+		ObjectOutputStream oos = new ObjectOutputStream(bos);
+		oos.writeObject(event);
+		oos.close();
+		event = (MyEvent) new ObjectInputStream(new ByteArrayInputStream(
+				bos.toByteArray())).readObject();
+		doTestEvents(this.listener, this.parentListener, event);
+	}
+
+	protected void doTestEvents(TestListener listener, TestListener parentListener,
+			MyEvent event) {
 		listener.zeroCounter();
 		parentListener.zeroCounter();
 		assertTrue("0 events before publication", listener.getEventCount() == 0);
 		assertTrue("0 parent events before publication", parentListener.getEventCount() == 0);
-		this.applicationContext.publishEvent(new MyEvent(this));
+		this.applicationContext.publishEvent(event);
 		assertTrue("1 events after publication, not " + listener.getEventCount(), listener.getEventCount() == 1);
 		assertTrue("1 parent events after publication", parentListener.getEventCount() == 1);
 	}

spring-webmvc-portlet/src/test/java/org/springframework/web/portlet/context/AbstractXmlWebApplicationContextTests.java

@@ -45,19 +45,13 @@ public abstract class AbstractXmlWebApplicationContextTests extends AbstractAppl
 	 * @see org.springframework.context.AbstractApplicationContextTests#testEvents()
 	 */
 	@Override
-	public void testEvents() throws Exception {
-		TestListener listener = (TestListener) this.applicationContext.getBean("testListener");
-		listener.zeroCounter();
-		TestListener parentListener = (TestListener) this.applicationContext.getParent().getBean("parentListener");
-		parentListener.zeroCounter();
-
-		parentListener.zeroCounter();
-		assertTrue("0 events before publication", listener.getEventCount() == 0);
-		assertTrue("0 parent events before publication", parentListener.getEventCount() == 0);
-		this.applicationContext.publishEvent(new MyEvent(this));
-		assertTrue("1 events after publication, not " + listener.getEventCount(), listener.getEventCount() == 1);
-		assertTrue("1 parent events after publication", parentListener.getEventCount() == 1);
-	}
+	protected void doTestEvents(TestListener listener, TestListener parentListener,
+			MyEvent event) {
+		TestListener listenerBean = (TestListener) this.applicationContext.getBean("testListener");
+		TestListener parentListenerBean = (TestListener) this.applicationContext.getParent().getBean("parentListener");
+		super.doTestEvents(listenerBean, parentListenerBean, event);
+
+	};
 
 	@Override
 	public void testCount() {

spring-webmvc/src/test/java/org/springframework/web/context/XmlWebApplicationContextTests.java

@@ -96,18 +96,11 @@ public void testEnvironmentMerge() {
 	 * @see org.springframework.context.AbstractApplicationContextTests#testEvents()
 	 */
 	@Override
-	public void testEvents() throws Exception {
-		TestListener listener = (TestListener) this.applicationContext.getBean("testListener");
-		listener.zeroCounter();
-		TestListener parentListener = (TestListener) this.applicationContext.getParent().getBean("parentListener");
-		parentListener.zeroCounter();
-
-		parentListener.zeroCounter();
-		assertTrue("0 events before publication", listener.getEventCount() == 0);
-		assertTrue("0 parent events before publication", parentListener.getEventCount() == 0);
-		this.applicationContext.publishEvent(new MyEvent(this));
-		assertTrue("1 events after publication, not " + listener.getEventCount(), listener.getEventCount() == 1);
-		assertTrue("1 parent events after publication", parentListener.getEventCount() == 1);
+	protected void doTestEvents(TestListener listener, TestListener parentListener,
+			MyEvent event) {
+		TestListener listenerBean = (TestListener) this.applicationContext.getBean("testListener");
+		TestListener parentListenerBean = (TestListener) this.applicationContext.getParent().getBean("parentListener");
+		super.doTestEvents(listenerBean, parentListenerBean, event);
 	}
 
 	@Override