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Resolve ApplicationListener against BeanDefinition.getResolvableType()

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This covers ApplicationListener generics in factory method return types in particular but also allows for programmatic setTargetType hints.

Closes gh-23178
This commit is contained in:
Juergen Hoeller
2019-07-20 15:05:38 +02:00
parent 8aa0b07768
commit daf29118a6
5 changed files with 131 additions and 20 deletions
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81
spring-context/src/main/java/org/springframework/context/event/AbstractApplicationEventMulticaster.java
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@@ -29,6 +29,7 @@ import org.springframework.beans.factory.BeanClassLoaderAware;
import org.springframework.beans.factory.BeanFactory;
import org.springframework.beans.factory.BeanFactoryAware;
import org.springframework.beans.factory.NoSuchBeanDefinitionException;
import org.springframework.beans.factory.config.BeanDefinition;
import org.springframework.beans.factory.config.ConfigurableBeanFactory;
import org.springframework.context.ApplicationEvent;
import org.springframework.context.ApplicationListener;
@@ -70,7 +71,7 @@ public abstract class AbstractApplicationEventMulticaster
private ClassLoader beanClassLoader;
@Nullable
private BeanFactory beanFactory;
private ConfigurableBeanFactory beanFactory;
private Object retrievalMutex = this.defaultRetriever;
@@ -82,17 +83,17 @@ public abstract class AbstractApplicationEventMulticaster
@Override
public void setBeanFactory(BeanFactory beanFactory) {
this.beanFactory = beanFactory;
if (beanFactory instanceof ConfigurableBeanFactory) {
ConfigurableBeanFactory cbf = (ConfigurableBeanFactory) beanFactory;
if (this.beanClassLoader == null) {
this.beanClassLoader = cbf.getBeanClassLoader();
}
this.retrievalMutex = cbf.getSingletonMutex();
if (!(beanFactory instanceof ConfigurableBeanFactory)) {
throw new IllegalStateException("Not running in a ConfigurableBeanFactory: " + beanFactory);
}
this.beanFactory = (ConfigurableBeanFactory) beanFactory;
if (this.beanClassLoader == null) {
this.beanClassLoader = this.beanFactory.getBeanClassLoader();
}
this.retrievalMutex = this.beanFactory.getSingletonMutex();
}
private BeanFactory getBeanFactory() {
private ConfigurableBeanFactory getBeanFactory() {
if (this.beanFactory == null) {
throw new IllegalStateException("ApplicationEventMulticaster cannot retrieve listener beans " +
"because it is not associated with a BeanFactory");
@@ -221,6 +222,9 @@ public abstract class AbstractApplicationEventMulticaster
listeners = new LinkedHashSet<>(this.defaultRetriever.applicationListeners);
listenerBeans = new LinkedHashSet<>(this.defaultRetriever.applicationListenerBeans);
}
// Add programmatically registered listeners, including ones coming
// from ApplicationListenerDetector (singleton beans and inner beans).
for (ApplicationListener<?> listener : listeners) {
if (supportsEvent(listener, eventType, sourceType)) {
if (retriever != null) {
@@ -229,12 +233,14 @@ public abstract class AbstractApplicationEventMulticaster
allListeners.add(listener);
}
}
// Add listeners by bean name, potentially overlapping with programmatically
// registered listeners above - but here potentially with additional metadata.
if (!listenerBeans.isEmpty()) {
BeanFactory beanFactory = getBeanFactory();
ConfigurableBeanFactory beanFactory = getBeanFactory();
for (String listenerBeanName : listenerBeans) {
try {
Class<?> listenerType = beanFactory.getType(listenerBeanName);
if (listenerType == null || supportsEvent(listenerType, eventType)) {
if (supportsEvent(beanFactory, listenerBeanName, eventType)) {
ApplicationListener<?> listener =
beanFactory.getBean(listenerBeanName, ApplicationListener.class);
if (!allListeners.contains(listener) && supportsEvent(listener, eventType, sourceType)) {
@@ -249,6 +255,16 @@ public abstract class AbstractApplicationEventMulticaster
allListeners.add(listener);
}
}
else {
// Remove non-matching listeners that originally came from
// ApplicationListenerDetector, possibly ruled out by additional
// BeanDefinition metadata (e.g. factory method generics) above.
Object listener = beanFactory.getSingleton(listenerBeanName);
if (retriever != null) {
retriever.applicationListeners.remove(listener);
}
allListeners.remove(listener);
}
}
catch (NoSuchBeanDefinitionException ex) {
// Singleton listener instance (without backing bean definition) disappeared -
@@ -256,6 +272,7 @@ public abstract class AbstractApplicationEventMulticaster
}
}
}
AnnotationAwareOrderComparator.sort(allListeners);
if (retriever != null && retriever.applicationListenerBeans.isEmpty()) {
retriever.applicationListeners.clear();
@@ -264,6 +281,42 @@ public abstract class AbstractApplicationEventMulticaster
return allListeners;
}
/**
* Filter a bean-defined listener early through checking its generically declared
* event type before trying to instantiate it.
* <p>If this method returns {@code true} for a given listener as a first pass,
* the listener instance will get retrieved and fully evaluated through a
* {@link #supportsEvent(ApplicationListener, ResolvableType, Class)} call afterwards.
* @param beanFactory the BeanFactory that contains the listener beans
* @param listenerBeanName the name of the bean in the BeanFactory
* @param eventType the event type to check
* @return whether the given listener should be included in the candidates
* for the given event type
* @see #supportsEvent(Class, ResolvableType)
* @see #supportsEvent(ApplicationListener, ResolvableType, Class)
*/
private boolean supportsEvent(
ConfigurableBeanFactory beanFactory, String listenerBeanName, ResolvableType eventType) {
Class<?> listenerType = beanFactory.getType(listenerBeanName);
if (listenerType == null || GenericApplicationListener.class.isAssignableFrom(listenerType) ||
SmartApplicationListener.class.isAssignableFrom(listenerType)) {
return true;
}
if (!supportsEvent(listenerType, eventType)) {
return false;
}
try {
BeanDefinition bd = beanFactory.getMergedBeanDefinition(listenerBeanName);
ResolvableType genericEventType = bd.getResolvableType().as(ApplicationListener.class).getGeneric();
return (genericEventType == ResolvableType.NONE || genericEventType.isAssignableFrom(eventType));
}
catch (NoSuchBeanDefinitionException ex) {
// Ignore - no need to check resolvable type for manually registered singleton
return true;
}
}
/**
* Filter a listener early through checking its generically declared event
* type before trying to instantiate it.
@@ -276,10 +329,6 @@ public abstract class AbstractApplicationEventMulticaster
* for the given event type
*/
protected boolean supportsEvent(Class<?> listenerType, ResolvableType eventType) {
if (GenericApplicationListener.class.isAssignableFrom(listenerType) ||
SmartApplicationListener.class.isAssignableFrom(listenerType)) {
return true;
}
ResolvableType declaredEventType = GenericApplicationListenerAdapter.resolveDeclaredEventType(listenerType);
return (declaredEventType == null || declaredEventType.isAssignableFrom(eventType));
}