/*
 * Copyright 2002-2019 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
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package org.springframework.context.event;

import org.springframework.context.ApplicationEvent;
import org.springframework.context.ApplicationListener;
import org.springframework.core.ResolvableType;
import org.springframework.lang.Nullable;

Interface to be implemented by objects that can manage a number of ApplicationListener objects and publish events to them. 
An ApplicationEventPublisher, typically a Spring ApplicationContext, can use an ApplicationEventMulticaster as a delegate for actually publishing events. 
Author:
Rod Johnson, Juergen Hoeller, Stephane Nicoll
See Also:
ApplicationListener/**
 * Interface to be implemented by objects that can manage a number of
 * {@link ApplicationListener} objects and publish events to them.
 *
 * <p>An {@link org.springframework.context.ApplicationEventPublisher}, typically
 * a Spring {@link org.springframework.context.ApplicationContext}, can use an
 * {@code ApplicationEventMulticaster} as a delegate for actually publishing events.
 *
 * @author Rod Johnson
 * @author Juergen Hoeller
 * @author Stephane Nicoll
 * @see ApplicationListener
 */
public interface ApplicationEventMulticaster {

	
Add a listener to be notified of all events.
Params:
listener – the listener to add/**
	 * Add a listener to be notified of all events.
	 * @param listener the listener to add
	 */
	void addApplicationListener(ApplicationListener<?> listener);

	
Add a listener bean to be notified of all events.
Params:
listenerBeanName – the name of the listener bean to add/**
	 * Add a listener bean to be notified of all events.
	 * @param listenerBeanName the name of the listener bean to add
	 */
	void addApplicationListenerBean(String listenerBeanName);

	
Remove a listener from the notification list.
Params:
listener – the listener to remove/**
	 * Remove a listener from the notification list.
	 * @param listener the listener to remove
	 */
	void removeApplicationListener(ApplicationListener<?> listener);

	
Remove a listener bean from the notification list.
Params:
listenerBeanName – the name of the listener bean to remove/**
	 * Remove a listener bean from the notification list.
	 * @param listenerBeanName the name of the listener bean to remove
	 */
	void removeApplicationListenerBean(String listenerBeanName);

	
Remove all listeners registered with this multicaster.
After a remove call, the multicaster will perform no action
on event notification until new listeners are registered.
/**
	 * Remove all listeners registered with this multicaster.
	 * <p>After a remove call, the multicaster will perform no action
	 * on event notification until new listeners are registered.
	 */
	void removeAllListeners();

	
Multicast the given application event to appropriate listeners.
Consider using multicastEvent(ApplicationEvent, ResolvableType) if possible as it provides better support for generics-based events. 
Params:
event – the event to multicast/**
	 * Multicast the given application event to appropriate listeners.
	 * <p>Consider using {@link #multicastEvent(ApplicationEvent, ResolvableType)}
	 * if possible as it provides better support for generics-based events.
	 * @param event the event to multicast
	 */
	void multicastEvent(ApplicationEvent event);

	
Multicast the given application event to appropriate listeners.
If the eventType is null, a default type is built based on the event instance. 
Params:
event – the event to multicast
eventType – the type of event (can be null)
Since:
4.2/**
	 * Multicast the given application event to appropriate listeners.
	 * <p>If the {@code eventType} is {@code null}, a default type is built
	 * based on the {@code event} instance.
	 * @param event the event to multicast
	 * @param eventType the type of event (can be {@code null})
	 * @since 4.2
	 */
	void multicastEvent(ApplicationEvent event, @Nullable ResolvableType eventType);

}