org.springframework.web.context.support.ServletContextScope Maven / Gradle / Ivy
/*
* Copyright 2002-2017 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
*
* http://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.web.context.support;
import java.util.LinkedHashMap;
import java.util.Map;
import javax.servlet.ServletContext;
import org.springframework.beans.factory.DisposableBean;
import org.springframework.beans.factory.ObjectFactory;
import org.springframework.beans.factory.config.Scope;
import org.springframework.lang.Nullable;
import org.springframework.util.Assert;
/**
* {@link Scope} wrapper for a ServletContext, i.e. for global web application attributes.
*
* This differs from traditional Spring singletons in that it exposes attributes in the
* ServletContext. Those attributes will get destroyed whenever the entire application
* shuts down, which might be earlier or later than the shutdown of the containing Spring
* ApplicationContext.
*
*
The associated destruction mechanism relies on a
* {@link org.springframework.web.context.ContextCleanupListener} being registered in
* {@code web.xml}. Note that {@link org.springframework.web.context.ContextLoaderListener}
* includes ContextCleanupListener's functionality.
*
*
This scope is registered as default scope with key
* {@link org.springframework.web.context.WebApplicationContext#SCOPE_APPLICATION "application"}.
*
* @author Juergen Hoeller
* @since 3.0
* @see org.springframework.web.context.ContextCleanupListener
*/
public class ServletContextScope implements Scope, DisposableBean {
private final ServletContext servletContext;
private final Map destructionCallbacks = new LinkedHashMap<>();
/**
* Create a new Scope wrapper for the given ServletContext.
* @param servletContext the ServletContext to wrap
*/
public ServletContextScope(ServletContext servletContext) {
Assert.notNull(servletContext, "ServletContext must not be null");
this.servletContext = servletContext;
}
@Override
public Object get(String name, ObjectFactory objectFactory) {
Object scopedObject = this.servletContext.getAttribute(name);
if (scopedObject == null) {
scopedObject = objectFactory.getObject();
this.servletContext.setAttribute(name, scopedObject);
}
return scopedObject;
}
@Override
@Nullable
public Object remove(String name) {
Object scopedObject = this.servletContext.getAttribute(name);
if (scopedObject != null) {
this.servletContext.removeAttribute(name);
this.destructionCallbacks.remove(name);
return scopedObject;
}
else {
return null;
}
}
@Override
public void registerDestructionCallback(String name, Runnable callback) {
this.destructionCallbacks.put(name, callback);
}
@Override
@Nullable
public Object resolveContextualObject(String key) {
return null;
}
@Override
@Nullable
public String getConversationId() {
return null;
}
/**
* Invoke all registered destruction callbacks.
* To be called on ServletContext shutdown.
* @see org.springframework.web.context.ContextCleanupListener
*/
@Override
public void destroy() {
for (Runnable runnable : this.destructionCallbacks.values()) {
runnable.run();
}
this.destructionCallbacks.clear();
}
}