001/*
002 * Copyright 2002-2019 the original author or authors.
003 *
004 * Licensed under the Apache License, Version 2.0 (the "License");
005 * you may not use this file except in compliance with the License.
006 * You may obtain a copy of the License at
007 *
008 *      https://www.apache.org/licenses/LICENSE-2.0
009 *
010 * Unless required by applicable law or agreed to in writing, software
011 * distributed under the License is distributed on an "AS IS" BASIS,
012 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
013 * See the License for the specific language governing permissions and
014 * limitations under the License.
015 */
016
017package org.springframework.context.event;
018
019import org.springframework.context.ApplicationEvent;
020import org.springframework.context.ApplicationListener;
021import org.springframework.core.ResolvableType;
022import org.springframework.lang.Nullable;
023
024/**
025 * Interface to be implemented by objects that can manage a number of
026 * {@link ApplicationListener} objects and publish events to them.
027 *
028 * <p>An {@link org.springframework.context.ApplicationEventPublisher}, typically
029 * a Spring {@link org.springframework.context.ApplicationContext}, can use an
030 * {@code ApplicationEventMulticaster} as a delegate for actually publishing events.
031 *
032 * @author Rod Johnson
033 * @author Juergen Hoeller
034 * @author Stephane Nicoll
035 * @see ApplicationListener
036 */
037public interface ApplicationEventMulticaster {
038
039        /**
040         * Add a listener to be notified of all events.
041         * @param listener the listener to add
042         */
043        void addApplicationListener(ApplicationListener<?> listener);
044
045        /**
046         * Add a listener bean to be notified of all events.
047         * @param listenerBeanName the name of the listener bean to add
048         */
049        void addApplicationListenerBean(String listenerBeanName);
050
051        /**
052         * Remove a listener from the notification list.
053         * @param listener the listener to remove
054         */
055        void removeApplicationListener(ApplicationListener<?> listener);
056
057        /**
058         * Remove a listener bean from the notification list.
059         * @param listenerBeanName the name of the listener bean to remove
060         */
061        void removeApplicationListenerBean(String listenerBeanName);
062
063        /**
064         * Remove all listeners registered with this multicaster.
065         * <p>After a remove call, the multicaster will perform no action
066         * on event notification until new listeners are registered.
067         */
068        void removeAllListeners();
069
070        /**
071         * Multicast the given application event to appropriate listeners.
072         * <p>Consider using {@link #multicastEvent(ApplicationEvent, ResolvableType)}
073         * if possible as it provides better support for generics-based events.
074         * @param event the event to multicast
075         */
076        void multicastEvent(ApplicationEvent event);
077
078        /**
079         * Multicast the given application event to appropriate listeners.
080         * <p>If the {@code eventType} is {@code null}, a default type is built
081         * based on the {@code event} instance.
082         * @param event the event to multicast
083         * @param eventType the type of event (can be {@code null})
084         * @since 4.2
085         */
086        void multicastEvent(ApplicationEvent event, @Nullable ResolvableType eventType);
087
088}