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Explicitly replace target ApplicationListener with singleton proxy, if any (avoiding double registration/invocation) 

Issue: SPR-15452
This commit is contained in:
Juergen Hoeller 2017-04-15 14:10:28 +02:00
parent 3efb76c852
commit 9abf249cee
3 changed files with 54 additions and 11 deletions
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30
spring-aop/src/main/java/org/springframework/aop/framework/AopProxyUtils.java
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@ -1,5 +1,5 @@
/*
* Copyright 2002-2016 the original author or authors.
* Copyright 2002-2017 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.
@ -43,6 +43,25 @@ import org.springframework.util.ObjectUtils;
*/
public abstract class AopProxyUtils {
/**
* Obtain the singleton target object behind the given proxy, if any.
* @param candidate the (potential) proxy to check
* @return the singleton target object managed in a {@link SingletonTargetSource},
* or {@code null} in any other case (not a proxy, not an existing singleton target)
* @since 4.3.8
* @see Advised#getTargetSource()
* @see SingletonTargetSource#getTarget()
*/
public static Object getSingletonTarget(Object candidate) {
if (candidate instanceof Advised) {
TargetSource targetSource = ((Advised) candidate).getTargetSource();
if (targetSource instanceof SingletonTargetSource) {
return ((SingletonTargetSource) targetSource).getTarget();
}
}
return null;
}
/**
* Determine the ultimate target class of the given bean instance, traversing
* not only a top-level proxy but any number of nested proxies as well —
@ -59,14 +78,7 @@ public abstract class AopProxyUtils {
Class<?> result = null;
while (current instanceof TargetClassAware) {
result = ((TargetClassAware) current).getTargetClass();
Object nested = null;
if (current instanceof Advised) {
TargetSource targetSource = ((Advised) current).getTargetSource();
if (targetSource instanceof SingletonTargetSource) {
nested = ((SingletonTargetSource) targetSource).getTarget();
}
}
current = nested;
current = getSingletonTarget(current);
}
if (result == null) {
result = (AopUtils.isCglibProxy(candidate) ? candidate.getClass().getSuperclass() : candidate.getClass());

7
spring-context/src/main/java/org/springframework/context/event/AbstractApplicationEventMulticaster.java
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@ -23,6 +23,7 @@ import java.util.Map;
import java.util.Set;
import java.util.concurrent.ConcurrentHashMap;
import org.springframework.aop.framework.AopProxyUtils;
import org.springframework.beans.factory.BeanClassLoaderAware;
import org.springframework.beans.factory.BeanFactory;
import org.springframework.beans.factory.BeanFactoryAware;
@ -98,6 +99,12 @@ public abstract class AbstractApplicationEventMulticaster
@Override
public void addApplicationListener(ApplicationListener<?> listener) {
synchronized (this.retrievalMutex) {
// Explicitly remove target for a proxy, if registered already,
// in order to avoid double invocations of the same listener.
Object singletonTarget = AopProxyUtils.getSingletonTarget(listener);
if (singletonTarget instanceof ApplicationListener) {
this.defaultRetriever.applicationListeners.remove(singletonTarget);
}
this.defaultRetriever.applicationListeners.add(listener);
this.retrieverCache.clear();
}

28
spring-context/src/test/java/org/springframework/context/event/ApplicationContextEventTests.java
View File

@ -1,5 +1,5 @@
/*
* Copyright 2002-2016 the original author or authors.
* Copyright 2002-2017 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.
@ -17,6 +17,8 @@
package org.springframework.context.event;
import java.util.HashSet;
import java.util.LinkedList;
import java.util.List;
import java.util.Set;
import java.util.concurrent.Executor;
@ -184,6 +186,7 @@ public class ApplicationContextEventTests extends AbstractApplicationEventListen
smc.multicastEvent(new MyEvent(this));
smc.multicastEvent(new MyOtherEvent(this));
assertEquals(2, listener1.seenEvents.size());
}
@Test
@ -197,6 +200,7 @@ public class ApplicationContextEventTests extends AbstractApplicationEventListen
smc.multicastEvent(new MyEvent(this));
smc.multicastEvent(new MyOtherEvent(this));
assertEquals(2, listener1.seenEvents.size());
}
@Test
@ -213,6 +217,26 @@ public class ApplicationContextEventTests extends AbstractApplicationEventListen
smc.multicastEvent(new MyEvent(this));
smc.multicastEvent(new MyOtherEvent(this));
assertEquals(2, listener1.seenEvents.size());
}
@Test
@SuppressWarnings("unchecked")
public void proxiedListenersMixedWithTargetListeners() {
MyOrderedListener1 listener1 = new MyOrderedListener1();
MyOrderedListener2 listener2 = new MyOrderedListener2(listener1);
ApplicationListener<ApplicationEvent> proxy1 = (ApplicationListener<ApplicationEvent>) new ProxyFactory(listener1).getProxy();
ApplicationListener<ApplicationEvent> proxy2 = (ApplicationListener<ApplicationEvent>) new ProxyFactory(listener2).getProxy();
SimpleApplicationEventMulticaster smc = new SimpleApplicationEventMulticaster();
smc.addApplicationListener(listener1);
smc.addApplicationListener(listener2);
smc.addApplicationListener(proxy1);
smc.addApplicationListener(proxy2);
smc.multicastEvent(new MyEvent(this));
smc.multicastEvent(new MyOtherEvent(this));
assertEquals(2, listener1.seenEvents.size());
}
@Test
@ -459,7 +483,7 @@ public class ApplicationContextEventTests extends AbstractApplicationEventListen
public static class MyOrderedListener1 implements ApplicationListener<ApplicationEvent>, Ordered {
public final Set<ApplicationEvent> seenEvents = new HashSet<>();
public final List<ApplicationEvent> seenEvents = new LinkedList<>();
@Override
public void onApplicationEvent(ApplicationEvent event) {