Merge branch '6.0.x'

spring-context/src/main/java/org/springframework/context/PayloadApplicationEvent.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2021 the original author or authors.
+ * Copyright 2002-2023 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.
@@ -41,19 +41,6 @@ public class PayloadApplicationEvent<T> extends ApplicationEvent implements Reso
 
 	private final ResolvableType payloadType;
 
-	/**
-	 * Create a new PayloadApplicationEvent.
-	 * @param source the object on which the event initially occurred (never {@code null})
-	 * @param payload the payload object (never {@code null})
-	 * @param payloadType the type object of payload object (can be {@code null})
-	 * @since 6.0
-	 */
-	public PayloadApplicationEvent(Object source, T payload, @Nullable ResolvableType payloadType) {
-		super(source);
-		Assert.notNull(payload, "Payload must not be null");
-		this.payload = payload;
-		this.payloadType = (payloadType != null) ? payloadType : ResolvableType.forInstance(payload);
-	}
 
 	/**
 	 * Create a new PayloadApplicationEvent, using the instance to infer its type.
@@ -64,6 +51,22 @@ public class PayloadApplicationEvent<T> extends ApplicationEvent implements Reso
 		this(source, payload, null);
 	}
 
+	/**
+	 * Create a new PayloadApplicationEvent based on the provided payload type.
+	 * @param source the object on which the event initially occurred (never {@code null})
+	 * @param payload the payload object (never {@code null})
+	 * @param payloadType the type object of payload object (can be {@code null}).
+	 * Note that this is meant to indicate the payload type (e.g. {@code String}),
+	 * not the full event type (such as {@code PayloadApplicationEvent<&lt;String&gt;}).
+	 * @since 6.0
+	 */
+	public PayloadApplicationEvent(Object source, T payload, @Nullable ResolvableType payloadType) {
+		super(source);
+		Assert.notNull(payload, "Payload must not be null");
+		this.payload = payload;
+		this.payloadType = (payloadType != null ? payloadType : ResolvableType.forInstance(payload));
+	}
+
 
 	@Override
 	public ResolvableType getResolvableType() {

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

@@ -128,12 +128,12 @@ public class SimpleApplicationEventMulticaster extends AbstractApplicationEventM
 
 	@Override
 	public void multicastEvent(ApplicationEvent event) {
-		multicastEvent(event, resolveDefaultEventType(event));
+		multicastEvent(event, null);
 	}
 
 	@Override
 	public void multicastEvent(ApplicationEvent event, @Nullable ResolvableType eventType) {
-		ResolvableType type = (eventType != null ? eventType : resolveDefaultEventType(event));
+		ResolvableType type = (eventType != null ? eventType : ResolvableType.forInstance(event));
 		Executor executor = getTaskExecutor();
 		for (ApplicationListener<?> listener : getApplicationListeners(event, type)) {
 			if (executor != null) {
@@ -145,10 +145,6 @@ public class SimpleApplicationEventMulticaster extends AbstractApplicationEventM
 		}
 	}
 
-	private ResolvableType resolveDefaultEventType(ApplicationEvent event) {
-		return ResolvableType.forInstance(event);
-	}
-
 	/**
 	 * Invoke the given listener with the given event.
 	 * @param listener the ApplicationListener to invoke

spring-context/src/main/java/org/springframework/context/support/AbstractApplicationContext.java

@@ -385,23 +385,47 @@ public abstract class AbstractApplicationContext extends DefaultResourceLoader
 
 	/**
 	 * Publish the given event to all listeners.
+	 * <p>This is the internal delegate that all other {@code publishEvent}
+	 * methods refer to. It is not meant to be called directly but rather serves
+	 * as a propagation mechanism between application contexts in a hierarchy,
+	 * potentially overridden in subclasses for a custom propagation arrangement.
 	 * @param event the event to publish (may be an {@link ApplicationEvent}
 	 * or a payload object to be turned into a {@link PayloadApplicationEvent})
-	 * @param eventType the resolved event type, if known
+	 * @param typeHint the resolved event type, if known.
+	 * The implementation of this method also tolerates a payload type hint for
+	 * a payload object to be turned into a {@link PayloadApplicationEvent}.
+	 * However, the recommended way is to construct an actual event object via
+	 * {@link PayloadApplicationEvent#PayloadApplicationEvent(Object, Object, ResolvableType)}
+	 * instead for such scenarios.
 	 * @since 4.2
+	 * @see ApplicationEventMulticaster#multicastEvent(ApplicationEvent, ResolvableType)
 	 */
-	protected void publishEvent(Object event, @Nullable ResolvableType eventType) {
+	protected void publishEvent(Object event, @Nullable ResolvableType typeHint) {
 		Assert.notNull(event, "Event must not be null");
+		ResolvableType eventType = null;
 
 		// Decorate event as an ApplicationEvent if necessary
 		ApplicationEvent applicationEvent;
 		if (event instanceof ApplicationEvent applEvent) {
 			applicationEvent = applEvent;
+			eventType = typeHint;
 		}
 		else {
-			applicationEvent = new PayloadApplicationEvent<>(this, event, eventType);
-			if (eventType == null) {
-				eventType = ((PayloadApplicationEvent<?>) applicationEvent).getResolvableType();
+			ResolvableType payloadType = null;
+			if (typeHint != null && ApplicationEvent.class.isAssignableFrom(typeHint.toClass())) {
+				eventType = typeHint;
+			}
+			else {
+				payloadType = typeHint;
+			}
+			applicationEvent = new PayloadApplicationEvent<>(this, event, payloadType);
+		}
+
+		// Determine event type only once (for multicast and parent publish)
+		if (eventType == null) {
+			eventType = ResolvableType.forInstance(applicationEvent);
+			if (typeHint == null) {
+				typeHint = eventType;
 			}
 		}
 
@@ -416,7 +440,7 @@ public abstract class AbstractApplicationContext extends DefaultResourceLoader
 		// Publish event via parent context as well...
 		if (this.parent != null) {
 			if (this.parent instanceof AbstractApplicationContext abstractApplicationContext) {
-				abstractApplicationContext.publishEvent(event, eventType);
+				abstractApplicationContext.publishEvent(event, typeHint);
 			}
 			else {
 				this.parent.publishEvent(event);