org.springframework.web.context.request.AbstractRequestAttributesScope 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
*
* 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.web.context.request;
import org.springframework.beans.factory.ObjectFactory;
import org.springframework.beans.factory.config.Scope;
import org.springframework.lang.Nullable;
/**
* Abstract {@link Scope} implementation that reads from a particular scope
* in the current thread-bound {@link RequestAttributes} object.
*
* Subclasses simply need to implement {@link #getScope()} to instruct
* this class which {@link RequestAttributes} scope to read attributes from.
*
*
Subclasses may wish to override the {@link #get} and {@link #remove}
* methods to add synchronization around the call back into this super class.
*
* @author Rod Johnson
* @author Juergen Hoeller
* @author Rob Harrop
* @since 2.0
*/
public abstract class AbstractRequestAttributesScope implements Scope {
@Override
public Object get(String name, ObjectFactory objectFactory) {
RequestAttributes attributes = RequestContextHolder.currentRequestAttributes();
Object scopedObject = attributes.getAttribute(name, getScope());
if (scopedObject == null) {
scopedObject = objectFactory.getObject();
attributes.setAttribute(name, scopedObject, getScope());
// Retrieve object again, registering it for implicit session attribute updates.
// As a bonus, we also allow for potential decoration at the getAttribute level.
Object retrievedObject = attributes.getAttribute(name, getScope());
if (retrievedObject != null) {
// Only proceed with retrieved object if still present (the expected case).
// If it disappeared concurrently, we return our locally created instance.
scopedObject = retrievedObject;
}
}
return scopedObject;
}
@Override
@Nullable
public Object remove(String name) {
RequestAttributes attributes = RequestContextHolder.currentRequestAttributes();
Object scopedObject = attributes.getAttribute(name, getScope());
if (scopedObject != null) {
attributes.removeAttribute(name, getScope());
return scopedObject;
}
else {
return null;
}
}
@Override
public void registerDestructionCallback(String name, Runnable callback) {
RequestAttributes attributes = RequestContextHolder.currentRequestAttributes();
attributes.registerDestructionCallback(name, callback, getScope());
}
@Override
@Nullable
public Object resolveContextualObject(String key) {
RequestAttributes attributes = RequestContextHolder.currentRequestAttributes();
return attributes.resolveReference(key);
}
/**
* Template method that determines the actual target scope.
* @return the target scope, in the form of an appropriate
* {@link RequestAttributes} constant
* @see RequestAttributes#SCOPE_REQUEST
* @see RequestAttributes#SCOPE_SESSION
*/
protected abstract int getScope();
}