Java tutorial
/* * 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 * * 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 org.springframework.context.ApplicationEvent; import org.springframework.context.ApplicationListener; import org.springframework.core.Ordered; import org.springframework.lang.Nullable; /** * Extended variant of the standard {@link ApplicationListener} interface, * exposing further metadata such as the supported event and source type. * * <p>For full introspection of generic event types, consider implementing * the {@link GenericApplicationListener} interface instead. * * @author Juergen Hoeller * @since 3.0 * @see GenericApplicationListener * @see GenericApplicationListenerAdapter */ public interface SmartApplicationListener extends ApplicationListener<ApplicationEvent>, Ordered { /** * Determine whether this listener actually supports the given event type. * @param eventType the event type (never {@code null}) */ boolean supportsEventType(Class<? extends ApplicationEvent> eventType); /** * Determine whether this listener actually supports the given source type. * <p>The default implementation always returns {@code true}. * @param sourceType the source type, or {@code null} if no source */ default boolean supportsSourceType(@Nullable Class<?> sourceType) { return true; } /** * Determine this listener's order in a set of listeners for the same event. * <p>The default implementation returns {@link #LOWEST_PRECEDENCE}. */ @Override default int getOrder() { return LOWEST_PRECEDENCE; } }