org.springframework.context.event.SmartApplicationListener Maven / Gradle / Ivy
/*
* 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 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.
*
* 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, Ordered {
/**
* Determine whether this listener actually supports the given event type.
* @param eventType the event type (never {@code null})
*/
boolean supportsEventType(Class eventType);
/**
* Determine whether this listener actually supports the given source type.
* 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.
*
The default implementation returns {@link #LOWEST_PRECEDENCE}.
*/
@Override
default int getOrder() {
return LOWEST_PRECEDENCE;
}
/**
* Return an optional identifier for the listener.
*
The default value is an empty String.
* @since 5.3.5
* @see EventListener#id
* @see ApplicationEventMulticaster#removeApplicationListeners
*/
default String getListenerId() {
return "";
}
}