/* * Copyright 2002-2018 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. * You may obtain a copy of the License at * * http://www.apache.org/licenses/LICENSE-2.0 * * Unless required by applicable law or agreed to in writing, software * distributed under the License is distributed on an "AS IS" BASIS, * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. * See the License for the specific language governing permissions and * limitations under the License. */ package org.springframework.context.event; import java.util.Map; import org.springframework.aop.support.AopUtils; import org.springframework.context.ApplicationEvent; import org.springframework.context.ApplicationListener; import org.springframework.core.Ordered; import org.springframework.core.ResolvableType; import org.springframework.lang.Nullable; import org.springframework.util.Assert; import org.springframework.util.ConcurrentReferenceHashMap; /** * {@link GenericApplicationListener} adapter that determines supported event types * through introspecting the generically declared type of the target listener. * * @author Juergen Hoeller * @author Stephane Nicoll * @since 3.0 * @see org.springframework.context.ApplicationListener#onApplicationEvent */ public class GenericApplicationListenerAdapter implements GenericApplicationListener, SmartApplicationListener { private static final Map<Class<?>, ResolvableType> eventTypeCache = new ConcurrentReferenceHashMap<>(); private final ApplicationListener<ApplicationEvent> delegate; @Nullable private final ResolvableType declaredEventType; /** * Create a new GenericApplicationListener for the given delegate. * @param delegate the delegate listener to be invoked */ @SuppressWarnings("unchecked") public GenericApplicationListenerAdapter(ApplicationListener<?> delegate) { Assert.notNull(delegate, "Delegate listener must not be null"); this.delegate = (ApplicationListener<ApplicationEvent>) delegate; this.declaredEventType = resolveDeclaredEventType(this.delegate); } @Override public void onApplicationEvent(ApplicationEvent event) { this.delegate.onApplicationEvent(event); } @Override @SuppressWarnings("unchecked") public boolean supportsEventType(ResolvableType eventType) { if (this.delegate instanceof SmartApplicationListener) { Class<? extends ApplicationEvent> eventClass = (Class<? extends ApplicationEvent>) eventType.resolve(); return (eventClass != null && ((SmartApplicationListener) this.delegate).supportsEventType(eventClass)); } else { return (this.declaredEventType == null || this.declaredEventType.isAssignableFrom(eventType)); } } @Override public boolean supportsEventType(Class<? extends ApplicationEvent> eventType) { return supportsEventType(ResolvableType.forClass(eventType)); } @Override public boolean supportsSourceType(@Nullable Class<?> sourceType) { return !(this.delegate instanceof SmartApplicationListener) || ((SmartApplicationListener) this.delegate).supportsSourceType(sourceType); } @Override public int getOrder() { return (this.delegate instanceof Ordered ? ((Ordered) this.delegate).getOrder() : Ordered.LOWEST_PRECEDENCE); } @Nullable private static ResolvableType resolveDeclaredEventType(ApplicationListener<ApplicationEvent> listener) { ResolvableType declaredEventType = resolveDeclaredEventType(listener.getClass()); if (declaredEventType == null || declaredEventType.isAssignableFrom(ApplicationEvent.class)) { Class<?> targetClass = AopUtils.getTargetClass(listener); if (targetClass != listener.getClass()) { declaredEventType = resolveDeclaredEventType(targetClass); } } return declaredEventType; } @Nullable static ResolvableType resolveDeclaredEventType(Class<?> listenerType) { ResolvableType eventType = eventTypeCache.get(listenerType); if (eventType == null) { eventType = ResolvableType.forClass(listenerType).as(ApplicationListener.class).getGeneric(); eventTypeCache.put(listenerType, eventType); } return (eventType != ResolvableType.NONE ? eventType : null); } }