/*
* Copyright 2002-2008 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.aop.aspectj.autoproxy;
import java.util.Comparator;
import java.util.LinkedList;
import java.util.List;
import org.aopalliance.aop.Advice;
import org.aspectj.util.PartialOrder;
import org.aspectj.util.PartialOrder.PartialComparable;
import org.springframework.aop.Advisor;
import org.springframework.aop.aspectj.AbstractAspectJAdvice;
import org.springframework.aop.aspectj.AspectJPointcutAdvisor;
import org.springframework.aop.aspectj.AspectJProxyUtils;
import org.springframework.aop.framework.autoproxy.AbstractAdvisorAutoProxyCreator;
import org.springframework.aop.interceptor.ExposeInvocationInterceptor;
import org.springframework.core.Ordered;
import org.springframework.util.ClassUtils;
/**
* {@link org.springframework.aop.framework.autoproxy.AbstractAdvisorAutoProxyCreator}
* subclass that exposes AspectJ's invocation context and understands AspectJ's rules
* for advice precedence when multiple pieces of advice come from the same aspect.
*
* @author Adrian Colyer
* @author Juergen Hoeller
* @author Ramnivas Laddad
* @since 2.0
*/
public class AspectJAwareAdvisorAutoProxyCreator extends AbstractAdvisorAutoProxyCreator {
private static final Comparator DEFAULT_PRECEDENCE_COMPARATOR = new AspectJPrecedenceComparator();
/**
* Sort the rest by AspectJ precedence. If two pieces of advice have
* come from the same aspect they will have the same order.
* Advice from the same aspect is then further ordered according to the
* following rules:
* <ul>
* <li>if either of the pair is after advice, then the advice declared
* last gets highest precedence (runs last)</li>
* <li>otherwise the advice declared first gets highest precedence (runs first)</li>
* </ul>
* <p><b>Important:</b> Advisors are sorted in precedence order, from highest
* precedence to lowest. "On the way in" to a join point, the highest precedence
* advisor should run first. "On the way out" of a join point, the highest precedence
* advisor should run last.
*/
@Override
@SuppressWarnings("unchecked")
protected List<Advisor> sortAdvisors(List<Advisor> advisors) {
// build list for sorting
List<PartiallyComparableAdvisorHolder> partiallyComparableAdvisors =
new LinkedList<PartiallyComparableAdvisorHolder>();
for (Advisor element : advisors) {
partiallyComparableAdvisors.add(
new PartiallyComparableAdvisorHolder(element, DEFAULT_PRECEDENCE_COMPARATOR));
}
// sort it
List<PartiallyComparableAdvisorHolder> sorted =
(List<PartiallyComparableAdvisorHolder>) PartialOrder.sort(partiallyComparableAdvisors);
if (sorted == null) {
// TODO: work harder to give a better error message here.
throw new IllegalArgumentException("Advice precedence circularity error");
}
// extract results again
List<Advisor> result = new LinkedList<Advisor>();
for (PartiallyComparableAdvisorHolder pcAdvisor : sorted) {
result.add(pcAdvisor.getAdvisor());
}
return result;
}
/**
* Adds an {@link ExposeInvocationInterceptor} to the beginning of the advice chain.
* These additional advices are needed when using AspectJ expression pointcuts
* and when using AspectJ-style advice.
*/
@Override
protected void extendAdvisors(List<Advisor> candidateAdvisors) {
AspectJProxyUtils.makeAdvisorChainAspectJCapableIfNecessary(candidateAdvisors);
}
@Override
protected boolean shouldSkip(Class beanClass, String beanName) {
// TODO: Consider optimization by caching the list of the aspect names
List<Advisor> candidateAdvisors = findCandidateAdvisors();
for (Advisor advisor : candidateAdvisors) {
if (advisor instanceof AspectJPointcutAdvisor) {
if (((AbstractAspectJAdvice) advisor.getAdvice()).getAspectName().equals(beanName)) {
return true;
}
}
}
return super.shouldSkip(beanClass, beanName);
}
/**
* Implements AspectJ PartialComparable interface for defining partial orderings.
*/
private static class PartiallyComparableAdvisorHolder implements PartialComparable {
private final Advisor advisor;
private final Comparator<Advisor> comparator;
public PartiallyComparableAdvisorHolder(Advisor advisor, Comparator<Advisor> comparator) {
this.advisor = advisor;
this.comparator = comparator;
}
public int compareTo(Object obj) {
Advisor otherAdvisor = ((PartiallyComparableAdvisorHolder) obj).advisor;
return this.comparator.compare(this.advisor, otherAdvisor);
}
public int fallbackCompareTo(Object obj) {
return 0;
}
public Advisor getAdvisor() {
return this.advisor;
}
@Override
public String toString() {
StringBuilder sb = new StringBuilder();
Advice advice = this.advisor.getAdvice();
sb.append(ClassUtils.getShortName(advice.getClass()));
sb.append(": ");
if (this.advisor instanceof Ordered) {
sb.append("order ").append(((Ordered) this.advisor).getOrder()).append(", ");
}
if (advice instanceof AbstractAspectJAdvice) {
AbstractAspectJAdvice ajAdvice = (AbstractAspectJAdvice) advice;
sb.append(ajAdvice.getAspectName());
sb.append(", declaration order ");
sb.append(ajAdvice.getDeclarationOrder());
}
return sb.toString();
}
}
}
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