spring GenericApplicationListenerAdapter 源码

spring GenericApplicationListenerAdapter 代码

文件路径：/spring-context/src/main/java/org/springframework/context/event/GenericApplicationListenerAdapter.java

/*
 * Copyright 2002-2021 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
 *
 *      https://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 {

	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 GenericApplicationListener) {
			return ((GenericApplicationListener) this.delegate).supportsEventType(eventType);
		}
		else 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 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);
	}

	@Override
	public String getListenerId() {
		return (this.delegate instanceof SmartApplicationListener ?
				((SmartApplicationListener) this.delegate).getListenerId() : "");
	}


	@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);
	}

}

相关信息

spring 源码目录

相关文章

spring AbstractApplicationEventMulticaster 源码

spring ApplicationContextEvent 源码

spring ApplicationEventMulticaster 源码

spring ApplicationListenerMethodAdapter 源码

spring ContextClosedEvent 源码

spring ContextRefreshedEvent 源码

spring ContextStartedEvent 源码

spring ContextStoppedEvent 源码

spring DefaultEventListenerFactory 源码

spring EventExpressionEvaluator 源码