/*
* Copyright 2002-2016 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.annotation;
import java.lang.annotation.Annotation;
import java.lang.reflect.Constructor;
import java.lang.reflect.Field;
import java.lang.reflect.Method;
import java.lang.reflect.Modifier;
import java.util.HashMap;
import java.util.Map;
import java.util.StringTokenizer;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.aspectj.lang.annotation.After;
import org.aspectj.lang.annotation.AfterReturning;
import org.aspectj.lang.annotation.AfterThrowing;
import org.aspectj.lang.annotation.Around;
import org.aspectj.lang.annotation.Aspect;
import org.aspectj.lang.annotation.Before;
import org.aspectj.lang.annotation.Pointcut;
import org.aspectj.lang.reflect.AjType;
import org.aspectj.lang.reflect.AjTypeSystem;
import org.aspectj.lang.reflect.PerClauseKind;
import org.springframework.aop.framework.AopConfigException;
import org.springframework.core.ParameterNameDiscoverer;
import org.springframework.core.annotation.AnnotationUtils;
import org.springframework.util.StringUtils;
/**
* Abstract base class for factories that can create Spring AOP Advisors
* given AspectJ classes from classes honoring the AspectJ 5 annotation syntax.
*
* <p>This class handles annotation parsing and validation functionality.
* It does not actually generate Spring AOP Advisors, which is deferred to subclasses.
*
* @author Rod Johnson
* @author Adrian Colyer
* @author Juergen Hoeller
* @since 2.0
*/
public abstract class AbstractAspectJAdvisorFactory implements AspectJAdvisorFactory {
private static final String AJC_MAGIC = "ajc$";
/** Logger available to subclasses */
protected final Log logger = LogFactory.getLog(getClass());
protected final ParameterNameDiscoverer parameterNameDiscoverer = new AspectJAnnotationParameterNameDiscoverer();
/**
* We consider something to be an AspectJ aspect suitable for use by the Spring AOP system
* if it has the @Aspect annotation, and was not compiled by ajc. The reason for this latter test
* is that aspects written in the code-style (AspectJ language) also have the annotation present
* when compiled by ajc with the -1.5 flag, yet they cannot be consumed by Spring AOP.
*/
@Override
public boolean isAspect(Class<?> clazz) {
return (hasAspectAnnotation(clazz) && !compiledByAjc(clazz));
}
private boolean hasAspectAnnotation(Class<?> clazz) {
return (AnnotationUtils.findAnnotation(clazz, Aspect.class) != null);
}
/**
* We need to detect this as "code-style" AspectJ aspects should not be
* interpreted by Spring AOP.
*/
private boolean compiledByAjc(Class<?> clazz) {
// The AJTypeSystem goes to great lengths to provide a uniform appearance between code-style and
// annotation-style aspects. Therefore there is no 'clean' way to tell them apart. Here we rely on
// an implementation detail of the AspectJ compiler.
for (Field field : clazz.getDeclaredFields()) {
if (field.getName().startsWith(AJC_MAGIC)) {
return true;
}
}
return false;
}
@Override
public void validate(Class<?> aspectClass) throws AopConfigException {
// If the parent has the annotation and isn't abstract it's an error
if (aspectClass.getSuperclass().getAnnotation(Aspect.class) != null &&
!Modifier.isAbstract(aspectClass.getSuperclass().getModifiers())) {
throw new AopConfigException("[" + aspectClass.getName() + "] cannot extend concrete aspect [" +
aspectClass.getSuperclass().getName() + "]");
}
AjType<?> ajType = AjTypeSystem.getAjType(aspectClass);
if (!ajType.isAspect()) {
throw new NotAnAtAspectException(aspectClass);
}
if (ajType.getPerClause().getKind() == PerClauseKind.PERCFLOW) {
throw new AopConfigException(aspectClass.getName() + " uses percflow instantiation model: " +
"This is not supported in Spring AOP.");
}
if (ajType.getPerClause().getKind() == PerClauseKind.PERCFLOWBELOW) {
throw new AopConfigException(aspectClass.getName() + " uses percflowbelow instantiation model: " +
"This is not supported in Spring AOP.");
}
}
/**
* Find and return the first AspectJ annotation on the given method
* (there <i>should</i> only be one anyway...)
*/
@SuppressWarnings("unchecked")
protected static AspectJAnnotation<?> findAspectJAnnotationOnMethod(Method method) {
Class<?>[] classesToLookFor = new Class<?>[] {
Before.class, Around.class, After.class, AfterReturning.class, AfterThrowing.class, Pointcut.class};
for (Class<?> c : classesToLookFor) {
AspectJAnnotation<?> foundAnnotation = findAnnotation(method, (Class<Annotation>) c);
if (foundAnnotation != null) {
return foundAnnotation;
}
}
return null;
}
private static <A extends Annotation> AspectJAnnotation<A> findAnnotation(Method method, Class<A> toLookFor) {
A result = AnnotationUtils.findAnnotation(method, toLookFor);
if (result != null) {
return new AspectJAnnotation<>(result);
}
else {
return null;
}
}
protected enum AspectJAnnotationType {
AtPointcut,
AtBefore,
AtAfter,
AtAfterReturning,
AtAfterThrowing,
AtAround
}
/**
* Class modelling an AspectJ annotation, exposing its type enumeration and
* pointcut String.
*/
protected static class AspectJAnnotation<A extends Annotation> {
private static final String[] EXPRESSION_PROPERTIES = new String[] {"value", "pointcut"};
private static Map<Class<?>, AspectJAnnotationType> annotationTypes = new HashMap<>();
static {
annotationTypes.put(Pointcut.class,AspectJAnnotationType.AtPointcut);
annotationTypes.put(After.class,AspectJAnnotationType.AtAfter);
annotationTypes.put(AfterReturning.class,AspectJAnnotationType.AtAfterReturning);
annotationTypes.put(AfterThrowing.class,AspectJAnnotationType.AtAfterThrowing);
annotationTypes.put(Around.class,AspectJAnnotationType.AtAround);
annotationTypes.put(Before.class,AspectJAnnotationType.AtBefore);
}
private final A annotation;
private final AspectJAnnotationType annotationType;
private final String pointcutExpression;
private final String argumentNames;
public AspectJAnnotation(A annotation) {
this.annotation = annotation;
this.annotationType = determineAnnotationType(annotation);
// We know these methods exist with the same name on each object,
// but need to invoke them reflectively as there isn't a common interface.
try {
this.pointcutExpression = resolveExpression(annotation);
this.argumentNames = (String) annotation.getClass().getMethod("argNames").invoke(annotation);
}
catch (Exception ex) {
throw new IllegalArgumentException(annotation + " cannot be an AspectJ annotation", ex);
}
}
private AspectJAnnotationType determineAnnotationType(A annotation) {
for (Class<?> type : annotationTypes.keySet()) {
if (type.isInstance(annotation)) {
return annotationTypes.get(type);
}
}
throw new IllegalStateException("Unknown annotation type: " + annotation.toString());
}
private String resolveExpression(A annotation) throws Exception {
String expression = null;
for (String methodName : EXPRESSION_PROPERTIES) {
Method method;
try {
method = annotation.getClass().getDeclaredMethod(methodName);
}
catch (NoSuchMethodException ex) {
method = null;
}
if (method != null) {
String candidate = (String) method.invoke(annotation);
if (StringUtils.hasText(candidate)) {
expression = candidate;
}
}
}
return expression;
}
public AspectJAnnotationType getAnnotationType() {
return this.annotationType;
}
public A getAnnotation() {
return this.annotation;
}
public String getPointcutExpression() {
return this.pointcutExpression;
}
public String getArgumentNames() {
return this.argumentNames;
}
@Override
public String toString() {
return this.annotation.toString();
}
}
/**
* ParameterNameDiscoverer implementation that analyzes the arg names
* specified at the AspectJ annotation level.
*/
private static class AspectJAnnotationParameterNameDiscoverer implements ParameterNameDiscoverer {
@Override
public String[] getParameterNames(Method method) {
if (method.getParameterCount() == 0) {
return new String[0];
}
AspectJAnnotation<?> annotation = findAspectJAnnotationOnMethod(method);
if (annotation == null) {
return null;
}
StringTokenizer strTok = new StringTokenizer(annotation.getArgumentNames(), ",");
if (strTok.countTokens() > 0) {
String[] names = new String[strTok.countTokens()];
for (int i = 0; i < names.length; i++) {
names[i] = strTok.nextToken();
}
return names;
}
else {
return null;
}
}
@Override
public String[] getParameterNames(Constructor<?> ctor) {
throw new UnsupportedOperationException("Spring AOP cannot handle constructor advice");
}
}
}