org.springframework.boot.builder.ParentContextCloserApplicationListener Maven / Gradle / Ivy
/*
* Copyright 2012-2018 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.boot.builder;
import java.lang.ref.WeakReference;
import org.springframework.beans.BeansException;
import org.springframework.boot.builder.ParentContextApplicationContextInitializer.ParentContextAvailableEvent;
import org.springframework.context.ApplicationContext;
import org.springframework.context.ApplicationContextAware;
import org.springframework.context.ApplicationListener;
import org.springframework.context.ConfigurableApplicationContext;
import org.springframework.context.event.ContextClosedEvent;
import org.springframework.core.Ordered;
import org.springframework.util.ObjectUtils;
/**
* Listener that closes the application context if its parent is closed. It listens for
* refresh events and grabs the current context from there, and then listens for closed
* events and propagates it down the hierarchy.
*
* @author Dave Syer
* @author Eric Bottard
*/
public class ParentContextCloserApplicationListener
implements ApplicationListener,
ApplicationContextAware, Ordered {
private int order = Ordered.LOWEST_PRECEDENCE - 10;
private ApplicationContext context;
@Override
public int getOrder() {
return this.order;
}
@Override
public void setApplicationContext(ApplicationContext context) throws BeansException {
this.context = context;
}
@Override
public void onApplicationEvent(ParentContextAvailableEvent event) {
maybeInstallListenerInParent(event.getApplicationContext());
}
private void maybeInstallListenerInParent(ConfigurableApplicationContext child) {
if (child == this.context
&& child.getParent() instanceof ConfigurableApplicationContext) {
ConfigurableApplicationContext parent = (ConfigurableApplicationContext) child
.getParent();
parent.addApplicationListener(createContextCloserListener(child));
}
}
/**
* Subclasses may override to create their own subclass of ContextCloserListener. This
* still enforces the use of a weak reference.
* @param child the child context
* @return the {@link ContextCloserListener} to use
*/
protected ContextCloserListener createContextCloserListener(
ConfigurableApplicationContext child) {
return new ContextCloserListener(child);
}
/**
* {@link ApplicationListener} to close the context.
*/
protected static class ContextCloserListener
implements ApplicationListener {
private WeakReference childContext;
public ContextCloserListener(ConfigurableApplicationContext childContext) {
this.childContext = new WeakReference<>(childContext);
}
@Override
public void onApplicationEvent(ContextClosedEvent event) {
ConfigurableApplicationContext context = this.childContext.get();
if ((context != null)
&& (event.getApplicationContext() == context.getParent())
&& context.isActive()) {
context.close();
}
}
@Override
public boolean equals(Object obj) {
if (this == obj) {
return true;
}
if (obj == null) {
return false;
}
if (obj instanceof ContextCloserListener) {
ContextCloserListener other = (ContextCloserListener) obj;
return ObjectUtils.nullSafeEquals(this.childContext.get(),
other.childContext.get());
}
return super.equals(obj);
}
@Override
public int hashCode() {
return ObjectUtils.nullSafeHashCode(this.childContext.get());
}
}
}