org.springframework.boot.availability.AvailabilityChangeEvent Maven / Gradle / Ivy
/*
* Copyright 2012-2020 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.boot.availability;
import org.springframework.context.ApplicationContext;
import org.springframework.context.ApplicationEvent;
import org.springframework.context.ApplicationEventPublisher;
import org.springframework.context.PayloadApplicationEvent;
import org.springframework.core.ResolvableType;
import org.springframework.util.Assert;
/**
* {@link ApplicationEvent} sent when the {@link AvailabilityState} of the application
* changes.
*
* Any application component can send such events to update the state of the application.
*
* @param the availability state type
* @author Brian Clozel
* @author Phillip Webb
* @since 2.3.0
*/
public class AvailabilityChangeEvent extends PayloadApplicationEvent {
/**
* Create a new {@link AvailabilityChangeEvent} instance.
* @param source the source of the event
* @param state the availability state (never {@code null})
*/
public AvailabilityChangeEvent(Object source, S state) {
super(source, state);
}
/**
* Return the changed availability state.
* @return the availability state
*/
public S getState() {
return getPayload();
}
@Override
public ResolvableType getResolvableType() {
return ResolvableType.forClassWithGenerics(getClass(), getStateType());
}
private Class getStateType() {
S state = getState();
if (state instanceof Enum) {
return ((Enum) state).getDeclaringClass();
}
return state.getClass();
}
/**
* Convenience method that can be used to publish an {@link AvailabilityChangeEvent}
* to the given application context.
* @param the availability state type
* @param context the context used to publish the event
* @param state the changed availability state
*/
public static void publish(ApplicationContext context, S state) {
Assert.notNull(context, "Context must not be null");
publish(context, context, state);
}
/**
* Convenience method that can be used to publish an {@link AvailabilityChangeEvent}
* to the given application context.
* @param the availability state type
* @param publisher the publisher used to publish the event
* @param source the source of the event
* @param state the changed availability state
*/
public static void publish(ApplicationEventPublisher publisher, Object source,
S state) {
Assert.notNull(publisher, "Publisher must not be null");
publisher.publishEvent(new AvailabilityChangeEvent<>(source, state));
}
}