介绍
- Spring AOP的实现逻辑在AnnotationAwareAspectJAutoProxyCreator类，AOP的核心在于Bean对象初始化过程中如何查找关联的advice并通过创建动态代理。
- 针对每个Bean在初始化过程中会遍历spring的context上下文查找所有的aop的切面对象，并针对切面对象的每个方法生成一个advisor对象用以匹配每个目标方法。
- 关于动态代理包括JdkDynamicAopProxy和ObjenesisCglibAopProxy，后者依赖于cglib的enhancer用法。
AnnotationAwareAspectJAutoProxyCreator
AnnotationAwareAspectJAutoProxyCreator
public abstract class AbstractAutoProxyCreator extends ProxyProcessorSupport
implements SmartInstantiationAwareBeanPostProcessor, BeanFactoryAware {
protected Object wrapIfNecessary(Object bean, String beanName, Object cacheKey) {
// 过滤无关不需要的类
if (beanName != null && this.targetSourcedBeans.contains(beanName)) {
return bean;
}
if (Boolean.FALSE.equals(this.advisedBeans.get(cacheKey))) {
return bean;
}
if (isInfrastructureClass(bean.getClass()) || shouldSkip(bean.getClass(), beanName)) {
this.advisedBeans.put(cacheKey, Boolean.FALSE);
return bean;
}
// 查找该Bean是否有关联的增强类，如果有则创建增强代理
Object[] specificInterceptors = getAdvicesAndAdvisorsForBean(bean.getClass(), beanName, null);
if (specificInterceptors != DO_NOT_PROXY) {
this.advisedBeans.put(cacheKey, Boolean.TRUE);
// 创建切面的代理对象
Object proxy = createProxy(
bean.getClass(), beanName, specificInterceptors, new SingletonTargetSource(bean));
this.proxyTypes.put(cacheKey, proxy.getClass());
return proxy;
}
this.advisedBeans.put(cacheKey, Boolean.FALSE);
return bean;
}
}
- wrapIfNecessary方法核心获取bean是否有相关的增强对象，如果存在增强对象就创建动态代理。
- 第一个核心逻辑是查找bean的相关的增强Advisor对象。
- 第二个核心逻辑是针对bean和增强对象创建代理对象proxy。
查找增强Advisor
public abstract class AbstractAutoProxyCreator extends ProxyProcessorSupport
implements SmartInstantiationAwareBeanPostProcessor, BeanFactoryAware {
@Override
protected Object[] getAdvicesAndAdvisorsForBean(Class<?> beanClass, String beanName, TargetSource targetSource) {
// 找到符合要求的Advisors
List<Advisor> advisors = findEligibleAdvisors(beanClass, beanName);
if (advisors.isEmpty()) {
return DO_NOT_PROXY;
}
return advisors.toArray();
}
protected List<Advisor> findEligibleAdvisors(Class<?> beanClass, String beanName) {
// 查找候选的candidateAdvisors
List<Advisor> candidateAdvisors = findCandidateAdvisors();
// 在候选的candidateAdvisors中查找能够应用到beanClass的Advisors
List<Advisor> eligibleAdvisors = findAdvisorsThatCanApply(candidateAdvisors, beanClass, beanName);
extendAdvisors(eligibleAdvisors);
if (!eligibleAdvisors.isEmpty()) {
eligibleAdvisors = sortAdvisors(eligibleAdvisors);
}
return eligibleAdvisors;
}
}
public class AnnotationAwareAspectJAutoProxyCreator extends AspectJAwareAdvisorAutoProxyCreator {
@Override
protected List<Advisor> findCandidateAdvisors() {
// Add all the Spring advisors found according to superclass rules.
List<Advisor> advisors = super.findCandidateAdvisors();
// 查找切面 Build Advisors for all AspectJ aspects in the bean factory.
advisors.addAll(this.aspectJAdvisorsBuilder.buildAspectJAdvisors());
return advisors;
}
}
public class BeanFactoryAspectJAdvisorsBuilder {
private final ListableBeanFactory beanFactory;
private final AspectJAdvisorFactory advisorFactory;
private volatile List<String> aspectBeanNames;
private final Map<String, List<Advisor>> advisorsCache = new ConcurrentHashMap<String, List<Advisor>>();
private final Map<String, MetadataAwareAspectInstanceFactory> aspectFactoryCache =
new ConcurrentHashMap<String, MetadataAwareAspectInstanceFactory>();
public List<Advisor> buildAspectJAdvisors() {
List<String> aspectNames = this.aspectBeanNames;
if (aspectNames == null) {
synchronized (this) {
aspectNames = this.aspectBeanNames;
if (aspectNames == null) {
List<Advisor> advisors = new LinkedList<Advisor>();
aspectNames = new LinkedList<String>();
// 查找所有的bean的名称
String[] beanNames = BeanFactoryUtils.beanNamesForTypeIncludingAncestors(
this.beanFactory, Object.class, true, false);
// 遍历所有的bean，判断是否是aspect的类
for (String beanName : beanNames) {
// 如果是aspect类，需要构建aspect的元数据AspectMetadata
Class<?> beanType = this.beanFactory.getType(beanName);
if (this.advisorFactory.isAspect(beanType)) {
aspectNames.add(beanName);
AspectMetadata amd = new AspectMetadata(beanType, beanName);
if (amd.getAjType().getPerClause().getKind() == PerClauseKind.SINGLETON) {
MetadataAwareAspectInstanceFactory factory =
new BeanFactoryAspectInstanceFactory(this.beanFactory, beanName);
// 创建Advisor的列表信息，advisorFactory是ReflectiveAspectJAdvisorFactory
// 获取切面类的增强方法advisor
List<Advisor> classAdvisors = this.advisorFactory.getAdvisors(factory);
if (this.beanFactory.isSingleton(beanName)) {
this.advisorsCache.put(beanName, classAdvisors);
}
else {
this.aspectFactoryCache.put(beanName, factory);
}
advisors.addAll(classAdvisors);
}
else {
MetadataAwareAspectInstanceFactory factory =
new PrototypeAspectInstanceFactory(this.beanFactory, beanName);
this.aspectFactoryCache.put(beanName, factory);
advisors.addAll(this.advisorFactory.getAdvisors(factory));
}
}
}
this.aspectBeanNames = aspectNames;
return advisors;
}
}
}
// 省略相关代码
}
}
- getAdvicesAndAdvisorsForBean调用findEligibleAdvisors查找beanClass对应的增强对象Advisor列表。
- 查找增强类的核心逻辑是遍历spring容器内的所有bean对象，如果是aspect切面类则获取Advisor对象。
- findCandidateAdvisors负责查找所有Advisor对象，内部通过buildAspectJAdvisors查找Advisor对象。
- buildAspectJAdvisors方法内部的advisorFactory是ReflectiveAspectJAdvisorFactory对象，通过advisorFactory的isAspect判断是否切面类，通过advisorFactory的getAdvisors获取Advisor对象。
- findAdvisorsThatCanApply负责过滤Advisor对象，过滤和beanClass相关的Advisor列表。
- Advisor对象是切面类的方法维度的对象，切面类的包含增强注解的方法都会对应一个Advisor对象。
ReflectiveAspectJAdvisorFactory
- ReflectiveAspectJAdvisorFactory的类继承关系如图所示，核心关注判断切面类的逻辑。
查找增强Advisor之查找切面类
public abstract class AbstractAspectJAdvisorFactory implements AspectJAdvisorFactory {
private static final String AJC_MAGIC = "ajc$";
private static final Class<?>[] ASPECTJ_ANNOTATION_CLASSES = new Class<?>[] {
Pointcut.class, Around.class, Before.class, After.class, AfterReturning.class, AfterThrowing.class};
protected final ParameterNameDiscoverer parameterNameDiscoverer = new AspectJAnnotationParameterNameDiscoverer();
@Override
public boolean isAspect(Class<?> clazz) {
return (hasAspectAnnotation(clazz) && !compiledByAjc(clazz));
}
private boolean hasAspectAnnotation(Class<?> clazz) {
return (AnnotationUtils.findAnnotation(clazz, Aspect.class) != null);
}
}
public abstract class AnnotationUtils {
public static <A extends Annotation> A findAnnotation(Class<?> clazz, Class<A> annotationType) {
return findAnnotation(clazz, annotationType, true);
}
private static <A extends Annotation> A findAnnotation(Class<?> clazz, Class<A> annotationType, boolean synthesize) {
if (annotationType == null) {
return null;
}
AnnotationCacheKey cacheKey = new AnnotationCacheKey(clazz, annotationType);
A result = (A) findAnnotationCache.get(cacheKey);
if (result == null) {
result = findAnnotation(clazz, annotationType, new HashSet<Annotation>());
if (result != null && synthesize) {
result = synthesizeAnnotation(result, clazz);
findAnnotationCache.put(cacheKey, result);
}
}
return result;
}
private static <A extends Annotation> A findAnnotation(Class<?> clazz, Class<A> annotationType, Set<Annotation> visited) {
try {
Annotation[] anns = clazz.getDeclaredAnnotations();
// 包含指定的注解
for (Annotation ann : anns) {
if (ann.annotationType() == annotationType) {
return (A) ann;
}
}
for (Annotation ann : anns) {
if (!isInJavaLangAnnotationPackage(ann) && visited.add(ann)) {
A annotation = findAnnotation(ann.annotationType(), annotationType, visited);
if (annotation != null) {
return annotation;
}
}
}
}
catch (Throwable ex) {
handleIntrospectionFailure(clazz, ex);
return null;
}
// 省略相关的代码
}
}
- AnnotationUtils的findAnnotation查找是否存在aspect的注解。
查找增强Advisor之获取Advisor
public class ReflectiveAspectJAdvisorFactory extends AbstractAspectJAdvisorFactory implements Serializable {
@Override
public List<Advisor> getAdvisors(MetadataAwareAspectInstanceFactory aspectInstanceFactory) {
Class<?> aspectClass = aspectInstanceFactory.getAspectMetadata().getAspectClass();
String aspectName = aspectInstanceFactory.getAspectMetadata().getAspectName();
validate(aspectClass);
MetadataAwareAspectInstanceFactory lazySingletonAspectInstanceFactory =
new LazySingletonAspectInstanceFactoryDecorator(aspectInstanceFactory);
List<Advisor> advisors = new ArrayList<Advisor>();
// getAdvisorMethods负责获取AdvisorMethods
for (Method method : getAdvisorMethods(aspectClass)) {
// 获取Advisor
Advisor advisor = getAdvisor(method, lazySingletonAspectInstanceFactory, advisors.size(), aspectName);
if (advisor != null) {
advisors.add(advisor);
}
}
if (!advisors.isEmpty() && lazySingletonAspectInstanceFactory.getAspectMetadata().isLazilyInstantiated()) {
Advisor instantiationAdvisor = new SyntheticInstantiationAdvisor(lazySingletonAspectInstanceFactory);
advisors.add(0, instantiationAdvisor);
}
for (Field field : aspectClass.getDeclaredFields()) {
Advisor advisor = getDeclareParentsAdvisor(field);
if (advisor != null) {
advisors.add(advisor);
}
}
return advisors;
}
private List<Method> getAdvisorMethods(Class<?> aspectClass) {
final List<Method> methods = new ArrayList<Method>();
ReflectionUtils.doWithMethods(aspectClass, new ReflectionUtils.MethodCallback() {
@Override
public void doWith(Method method) throws IllegalArgumentException {
// Exclude pointcuts
if (AnnotationUtils.getAnnotation(method, Pointcut.class) == null) {
methods.add(method);
}
}
});
Collections.sort(methods, METHOD_COMPARATOR);
return methods;
}
@Override
public Advisor getAdvisor(Method candidateAdviceMethod, MetadataAwareAspectInstanceFactory aspectInstanceFactory,
int declarationOrderInAspect, String aspectName) {
validate(aspectInstanceFactory.getAspectMetadata().getAspectClass());
// 获取 AspectJExpressionPointcut
AspectJExpressionPointcut expressionPointcut = getPointcut(
candidateAdviceMethod, aspectInstanceFactory.getAspectMetadata().getAspectClass());
if (expressionPointcut == null) {
return null;
}
// 创建Advisor对象InstantiationModelAwarePointcutAdvisorImpl
return new InstantiationModelAwarePointcutAdvisorImpl(expressionPointcut, candidateAdviceMethod,
this, aspectInstanceFactory, declarationOrderInAspect, aspectName);
}
private AspectJExpressionPointcut getPointcut(Method candidateAdviceMethod, Class<?> candidateAspectClass) {
// 查询对应的方法candidateAdviceMethod是否包含指定的aspect相关的注解
AspectJAnnotation<?> aspectJAnnotation =
AbstractAspectJAdvisorFactory.findAspectJAnnotationOnMethod(candidateAdviceMethod);
if (aspectJAnnotation == null) {
return null;
}
// 创建AspectJExpressionPointcut对象
AspectJExpressionPointcut ajexp =
new AspectJExpressionPointcut(candidateAspectClass, new String[0], new Class<?>[0]);
ajexp.setExpression(aspectJAnnotation.getPointcutExpression());
ajexp.setBeanFactory(this.beanFactory);
return ajexp;
}
}
public abstract class AbstractAspectJAdvisorFactory implements AspectJAdvisorFactory {
private static final String AJC_MAGIC = "ajc$";
private static final Class<?>[] ASPECTJ_ANNOTATION_CLASSES = new Class<?>[] {
Pointcut.class, Around.class, Before.class, After.class, AfterReturning.class, AfterThrowing.class};
@SuppressWarnings("unchecked")
protected static AspectJAnnotation<?> findAspectJAnnotationOnMethod(Method method) {
for (Class<?> clazz : ASPECTJ_ANNOTATION_CLASSES) {
AspectJAnnotation<?> foundAnnotation = findAnnotation(method, (Class<Annotation>) clazz);
if (foundAnnotation != null) {
return foundAnnotation;
}
}
return null;
}
}
- getAdvisorMethods负责从切面类aspectClass获取相关的Method。
- getAdvisor负责将包含aspct注解的Method转换成Advisor对象。
- findAspectJAnnotationOnMethod判断方法是否包含aspect注解如Around.class等
- 切面类aspectClass的每个包含aspect的注解method会生成AspectJExpressionPointcut对象，进而生成InstantiationModelAwarePointcutAdvisorImpl对象。
- 切面类包含aspect注解的method会生成Advisor对象，即InstantiationModelAwarePointcutAdvisorImpl对象
InstantiationModelAwarePointcutAdvisorImpl
- Advisor对象是InstantiationModelAwarePointcutAdvisorImpl对象。
查找增强Advisor之过滤Advisor
public abstract class AbstractAdvisorAutoProxyCreator extends AbstractAutoProxyCreator {
private BeanFactoryAdvisorRetrievalHelper advisorRetrievalHelper;
protected List<Advisor> findAdvisorsThatCanApply(
List<Advisor> candidateAdvisors, Class<?> beanClass, String beanName) {
ProxyCreationContext.setCurrentProxiedBeanName(beanName);
try {
return AopUtils.findAdvisorsThatCanApply(candidateAdvisors, beanClass);
}
finally {
ProxyCreationContext.setCurrentProxiedBeanName(null);
}
}
}
public abstract class AopUtils {
public static List<Advisor> findAdvisorsThatCanApply(List<Advisor> candidateAdvisors, Class<?> clazz) {
if (candidateAdvisors.isEmpty()) {
return candidateAdvisors;
}
List<Advisor> eligibleAdvisors = new LinkedList<Advisor>();
// 遍历所有的Advisor进行匹配返回符合的Advisor
for (Advisor candidate : candidateAdvisors) {
if (candidate instanceof IntroductionAdvisor && canApply(candidate, clazz)) {
eligibleAdvisors.add(candidate);
}
}
boolean hasIntroductions = !eligibleAdvisors.isEmpty();
for (Advisor candidate : candidateAdvisors) {
if (candidate instanceof IntroductionAdvisor) {
// already processed
continue;
}
if (canApply(candidate, clazz, hasIntroductions)) {
eligibleAdvisors.add(candidate);
}
}
return eligibleAdvisors;
}
public static boolean canApply(Advisor advisor, Class<?> targetClass) {
return canApply(advisor, targetClass, false);
}
public static boolean canApply(Advisor advisor, Class<?> targetClass, boolean hasIntroductions) {
if (advisor instanceof IntroductionAdvisor) {
return ((IntroductionAdvisor) advisor).getClassFilter().matches(targetClass);
}
else if (advisor instanceof PointcutAdvisor) {
PointcutAdvisor pca = (PointcutAdvisor) advisor;
return canApply(pca.getPointcut(), targetClass, hasIntroductions);
}
else {
return true;
}
}
public static boolean canApply(Pointcut pc, Class<?> targetClass, boolean hasIntroductions) {
if (!pc.getClassFilter().matches(targetClass)) {
return false;
}
MethodMatcher methodMatcher = pc.getMethodMatcher();
if (methodMatcher == MethodMatcher.TRUE) {
return true;
}
IntroductionAwareMethodMatcher introductionAwareMethodMatcher = null;
if (methodMatcher instanceof IntroductionAwareMethodMatcher) {
introductionAwareMethodMatcher = (IntroductionAwareMethodMatcher) methodMatcher;
}
Set<Class<?>> classes = new LinkedHashSet<Class<?>>(ClassUtils.getAllInterfacesForClassAsSet(targetClass));
classes.add(targetClass);
for (Class<?> clazz : classes) {
// 获取类下面的所有Method对象
Method[] methods = ReflectionUtils.getAllDeclaredMethods(clazz);
for (Method method : methods) {
if ((introductionAwareMethodMatcher != null &&
introductionAwareMethodMatcher.matches(method, targetClass, hasIntroductions)) ||
// methodMatcher包含AspectJExpressionPointcut
methodMatcher.matches(method, targetClass)) {
return true;
}
}
}
return false;
}
}
- findAdvisorsThatCanApply查找匹配的Advisors。
- findAdvisorsThatCanApply的条件是目标类的某个方法和Advisor匹配，只要目标类的某个方法和Advisor匹配上就表明该Advisor符合条件。
创建代理流程
AbstractAutoProxyCreator
public abstract class AbstractAutoProxyCreator extends ProxyProcessorSupport
implements SmartInstantiationAwareBeanPostProcessor, BeanFactoryAware {
protected Object createProxy(
Class<?> beanClass, String beanName, Object[] specificInterceptors, TargetSource targetSource) {
if (this.beanFactory instanceof ConfigurableListableBeanFactory) {
AutoProxyUtils.exposeTargetClass((ConfigurableListableBeanFactory) this.beanFactory, beanName, beanClass);
}
ProxyFactory proxyFactory = new ProxyFactory();
proxyFactory.copyFrom(this);
if (!proxyFactory.isProxyTargetClass()) {
if (shouldProxyTargetClass(beanClass, beanName)) {
proxyFactory.setProxyTargetClass(true);
}
else {
evaluateProxyInterfaces(beanClass, proxyFactory);
}
}
// 将拦截器Interceptors封装成增强器advisors
Advisor[] advisors = buildAdvisors(beanName, specificInterceptors);
// 加入增强器
proxyFactory.addAdvisors(advisors);
proxyFactory.setTargetSource(targetSource);
// 定制代理
customizeProxyFactory(proxyFactory);
proxyFactory.setFrozen(this.freezeProxy);
if (advisorsPreFiltered()) {
proxyFactory.setPreFiltered(true);
}
// 封装出proxyFactory并由它完成后续的工作
return proxyFactory.getProxy(getProxyClassLoader());
}
}
- ProxyFactory负责生成动态代理的Proxy对象。
- ProxyFactory设置了代理对象targetSource和拦截器对象advisors。
- ProxyFactory通过getProxy来生成动态代理的Proxy对象。
ProxyFactory
public class ProxyFactory extends ProxyCreatorSupport {
public Object getProxy(ClassLoader classLoader) {
// createAopProxy创建动态代理实现对象
// getProxy负责创建动态代理
return createAopProxy().getProxy(classLoader);
}
}
public class ProxyCreatorSupport extends AdvisedSupport {
protected final synchronized AopProxy createAopProxy() {
if (!this.active) {
activate();
}
// 这里我们需要注意的是 ，这里 createAopProxy 传入的是 this。也就是说这里参数传递实际上是ProxyFactroy
return getAopProxyFactory().createAopProxy(this);
}
}
public class DefaultAopProxyFactory implements AopProxyFactory, Serializable {
@Override
public AopProxy createAopProxy(AdvisedSupport config) throws AopConfigException {
if (config.isOptimize() || config.isProxyTargetClass() || hasNoUserSuppliedProxyInterfaces(config)) {
Class<?> targetClass = config.getTargetClass();
if (targetClass.isInterface() || Proxy.isProxyClass(targetClass)) {
return new JdkDynamicAopProxy(config);
}
return new ObjenesisCglibAopProxy(config);
}
else {
return new JdkDynamicAopProxy(config);
}
}
}
- createAopProxy会根据是否实现Interface来选用cglib还是jdk的动态代理。
- ObjenesisCglibAopProxy是cglib形式的动态代理。
- JdkDynamicAopProxy是jdk形式的动态代理。
CglibAopProxy
class CglibAopProxy implements AopProxy, Serializable {
@Override
public Object getProxy(ClassLoader classLoader) {
try {
// 获取代理类，rootClass表示的是被代理类
Class<?> rootClass = this.advised.getTargetClass();
Class<?> proxySuperClass = rootClass;
if (ClassUtils.isCglibProxyClass(rootClass)) {
proxySuperClass = rootClass.getSuperclass();
Class<?>[] additionalInterfaces = rootClass.getInterfaces();
for (Class<?> additionalInterface : additionalInterfaces) {
this.advised.addInterface(additionalInterface);
}
}
validateClassIfNecessary(proxySuperClass, classLoader);
// 配置 Enhancer
Enhancer enhancer = createEnhancer();
if (classLoader != null) {
enhancer.setClassLoader(classLoader);
if (classLoader instanceof SmartClassLoader &&
((SmartClassLoader) classLoader).isClassReloadable(proxySuperClass)) {
enhancer.setUseCache(false);
}
}
enhancer.setSuperclass(proxySuperClass);
enhancer.setInterfaces(AopProxyUtils.completeProxiedInterfaces(this.advised));
enhancer.setNamingPolicy(SpringNamingPolicy.INSTANCE);
enhancer.setStrategy(new ClassLoaderAwareUndeclaredThrowableStrategy(classLoader));
// 获取代理的回调方法
Callback[] callbacks = getCallbacks(rootClass);
Class<?>[] types = new Class<?>[callbacks.length];
for (int x = 0; x < types.length; x++) {
types[x] = callbacks[x].getClass();
}
enhancer.setCallbackFilter(new ProxyCallbackFilter(
this.advised.getConfigurationOnlyCopy(), this.fixedInterceptorMap, this.fixedInterceptorOffset));
enhancer.setCallbackTypes(types);
// 创建代理对象
return createProxyClassAndInstance(enhancer, callbacks);
}
catch (CodeGenerationException ex) {
}
catch (IllegalArgumentException ex) {
}
catch (Throwable ex) {
}
}
protected Object createProxyClassAndInstance(Enhancer enhancer, Callback[] callbacks) {
enhancer.setInterceptDuringConstruction(false);
enhancer.setCallbacks(callbacks);
return (this.constructorArgs != null ?
enhancer.create(this.constructorArgTypes, this.constructorArgs) :
enhancer.create());
}
}
- CglibAopProxy的核心通过Enhancer实现动态代理的创建。
- Enhancer的核心变量superclass代表被代理对象类，callbacks代表拦截器，callbackFilter代表callback的匹配过滤器。
Callback
class CglibAopProxy implements AopProxy, Serializable {
private Callback[] getCallbacks(Class<?> rootClass) throws Exception {
boolean exposeProxy = this.advised.isExposeProxy();
boolean isFrozen = this.advised.isFrozen();
boolean isStatic = this.advised.getTargetSource().isStatic();
Callback aopInterceptor = new DynamicAdvisedInterceptor(this.advised);
Callback targetInterceptor;
if (exposeProxy) {
targetInterceptor = (isStatic ?
new StaticUnadvisedExposedInterceptor(this.advised.getTargetSource().getTarget()) :
new DynamicUnadvisedExposedInterceptor(this.advised.getTargetSource()));
}
else {
targetInterceptor = (isStatic ?
new StaticUnadvisedInterceptor(this.advised.getTargetSource().getTarget()) :
new DynamicUnadvisedInterceptor(this.advised.getTargetSource()));
}
Callback targetDispatcher = (isStatic ?
new StaticDispatcher(this.advised.getTargetSource().getTarget()) : new SerializableNoOp());
// 回调集合。其中包含aopInterceptor 中包含了 Aspect 的增强
// advisedDispatcher 用于判断如果method是Advised.class声明的，则使用AdvisedDispatcher进行分发
Callback[] mainCallbacks = new Callback[] {
aopInterceptor,
targetInterceptor,
new SerializableNoOp(),
targetDispatcher, this.advisedDispatcher,
new EqualsInterceptor(this.advised),
new HashCodeInterceptor(this.advised)
};
Callback[] callbacks;
if (isStatic && isFrozen) {
// 省略相关的代码
}
else {
callbacks = mainCallbacks;
}
return callbacks;
}
}
- mainCallbacks包含了所有的拦截器，期中aopInterceptor是核心的aspect相关的拦截器对象。
- aopInterceptor是DynamicAdvisedInterceptor对象，是执行aop拦截的核心。
DynamicAdvisedInterceptor
class CglibAopProxy implements AopProxy, Serializable {
private static class DynamicAdvisedInterceptor implements MethodInterceptor, Serializable {
private final AdvisedSupport advised;
public DynamicAdvisedInterceptor(AdvisedSupport advised) {
this.advised = advised;
}
@Override
public Object intercept(Object proxy, Method method, Object[] args, MethodProxy methodProxy) throws Throwable {
Object oldProxy = null;
boolean setProxyContext = false;
Class<?> targetClass = null;
Object target = null;
try {
if (this.advised.exposeProxy) {
oldProxy = AopContext.setCurrentProxy(proxy);
setProxyContext = true;
}
target = getTarget();
if (target != null) {
targetClass = target.getClass();
}
List<Object> chain = this.advised.getInterceptorsAndDynamicInterceptionAdvice(method, targetClass);
Object retVal;
if (chain.isEmpty() && Modifier.isPublic(method.getModifiers())) {
Object[] argsToUse = AopProxyUtils.adaptArgumentsIfNecessary(method, args);
retVal = methodProxy.invoke(target, argsToUse);
}
else {
retVal = new CglibMethodInvocation(proxy, target, method, args, targetClass, chain, methodProxy).proceed();
}
retVal = processReturnType(proxy, target, method, retVal);
return retVal;
}
finally {
if (target != null) {
releaseTarget(target);
}
if (setProxyContext) {
AopContext.setCurrentProxy(oldProxy);
}
}
}
}
}
- DynamicAdvisedInterceptor#intercept通过getInterceptorsAndDynamicInterceptionAdvice查找被调用method关联的拦截器，拦截器不为空则创建CglibMethodInvocation执行代理过程。
callbackFilter
class CglibAopProxy implements AopProxy, Serializable {
private static final int AOP_PROXY = 0;
private static final int INVOKE_TARGET = 1;
private static final int NO_OVERRIDE = 2;
private static final int DISPATCH_TARGET = 3;
private static final int DISPATCH_ADVISED = 4;
private static final int INVOKE_EQUALS = 5;
private static final int INVOKE_HASHCODE = 6;
private static class ProxyCallbackFilter implements CallbackFilter {
private final AdvisedSupport advised;
private final Map<String, Integer> fixedInterceptorMap;
private final int fixedInterceptorOffset;
public ProxyCallbackFilter(AdvisedSupport advised, Map<String, Integer> fixedInterceptorMap, int fixedInterceptorOffset) {
this.advised = advised;
this.fixedInterceptorMap = fixedInterceptorMap;
this.fixedInterceptorOffset = fixedInterceptorOffset;
}
@Override
public int accept(Method method) {
if (AopUtils.isFinalizeMethod(method)) {
return NO_OVERRIDE;
}
if (!this.advised.isOpaque() && method.getDeclaringClass().isInterface() &&
method.getDeclaringClass().isAssignableFrom(Advised.class)) {
return DISPATCH_ADVISED;
}
if (AopUtils.isEqualsMethod(method)) {
return INVOKE_EQUALS;
}
if (AopUtils.isHashCodeMethod(method)) {
return INVOKE_HASHCODE;
}
Class<?> targetClass = this.advised.getTargetClass();
List<?> chain = this.advised.getInterceptorsAndDynamicInterceptionAdvice(method, targetClass);
boolean haveAdvice = !chain.isEmpty();
boolean exposeProxy = this.advised.isExposeProxy();
boolean isStatic = this.advised.getTargetSource().isStatic();
boolean isFrozen = this.advised.isFrozen();
if (haveAdvice || !isFrozen) {
if (exposeProxy) {
return AOP_PROXY;
}
String key = method.toString();
if (isStatic && isFrozen && this.fixedInterceptorMap.containsKey(key)) {
int index = this.fixedInterceptorMap.get(key);
return (index + this.fixedInterceptorOffset);
}
else {
return AOP_PROXY;
}
}
else {
if (exposeProxy || !isStatic) {
return INVOKE_TARGET;
}
Class<?> returnType = method.getReturnType();
if (returnType.isAssignableFrom(targetClass)) {
return INVOKE_TARGET;
}
else {
return DISPATCH_TARGET;
}
}
}
}
- callbackFilter#accept的在CglibAopProxy调用过程中被执行，如果匹配存在拦截器就返回AOP_PROXY执行aopInterceptor。
- advised.getInterceptorsAndDynamicInterceptionAdvice负责匹配当前被调用的method的拦截器。
DefaultAdvisorChainFactory
public class DefaultAdvisorChainFactory implements AdvisorChainFactory, Serializable {
@Override
public List<Object> getInterceptorsAndDynamicInterceptionAdvice(
Advised config, Method method, Class<?> targetClass) {
List<Object> interceptorList = new ArrayList<Object>(config.getAdvisors().length);
Class<?> actualClass = (targetClass != null ? targetClass : method.getDeclaringClass());
boolean hasIntroductions = hasMatchingIntroductions(config, actualClass);
AdvisorAdapterRegistry registry = GlobalAdvisorAdapterRegistry.getInstance();
for (Advisor advisor : config.getAdvisors()) {
if (advisor instanceof PointcutAdvisor) {
PointcutAdvisor pointcutAdvisor = (PointcutAdvisor) advisor;
if (config.isPreFiltered() || pointcutAdvisor.getPointcut().getClassFilter().matches(actualClass)) {
MethodMatcher mm = pointcutAdvisor.getPointcut().getMethodMatcher();
if (MethodMatchers.matches(mm, method, actualClass, hasIntroductions)) {
MethodInterceptor[] interceptors = registry.getInterceptors(advisor);
if (mm.isRuntime()) {
for (MethodInterceptor interceptor : interceptors) {
interceptorList.add(new InterceptorAndDynamicMethodMatcher(interceptor, mm));
}
}
else {
interceptorList.addAll(Arrays.asList(interceptors));
}
}
}
}
else if (advisor instanceof IntroductionAdvisor) {
IntroductionAdvisor ia = (IntroductionAdvisor) advisor;
if (config.isPreFiltered() || ia.getClassFilter().matches(actualClass)) {
Interceptor[] interceptors = registry.getInterceptors(advisor);
interceptorList.addAll(Arrays.asList(interceptors));
}
}
else {
Interceptor[] interceptors = registry.getInterceptors(advisor);
interceptorList.addAll(Arrays.asList(interceptors));
}
}
return interceptorList;
}
private static boolean hasMatchingIntroductions(Advised config, Class<?> actualClass) {
for (Advisor advisor : config.getAdvisors()) {
if (advisor instanceof IntroductionAdvisor) {
IntroductionAdvisor ia = (IntroductionAdvisor) advisor;
if (ia.getClassFilter().matches(actualClass)) {
return true;
}
}
}
return false;
}
}
- getInterceptorsAndDynamicInterceptionAdvice遍历所有的拦截器，根据类和方法进行过滤后返回匹配的拦截器。
CglibMethodInvocation
class CglibAopProxy implements AopProxy, Serializable {
private static class CglibMethodInvocation extends ReflectiveMethodInvocation {
private final MethodProxy methodProxy;
private final boolean publicMethod;
public CglibMethodInvocation(Object proxy, Object target, Method method, Object[] arguments,
Class<?> targetClass, List<Object> interceptorsAndDynamicMethodMatchers, MethodProxy methodProxy) {
super(proxy, target, method, arguments, targetClass, interceptorsAndDynamicMethodMatchers);
this.methodProxy = methodProxy;
this.publicMethod = Modifier.isPublic(method.getModifiers());
}
@Override
protected Object invokeJoinpoint() throws Throwable {
if (this.publicMethod) {
return this.methodProxy.invoke(this.target, this.arguments);
}
else {
return super.invokeJoinpoint();
}
}
}
}
public class ReflectiveMethodInvocation implements ProxyMethodInvocation, Cloneable {
protected final Object proxy;
protected final Object target;
protected final Method method;
protected Object[] arguments;
private final Class<?> targetClass;
private Map<String, Object> userAttributes;
protected final List<?> interceptorsAndDynamicMethodMatchers;
private int currentInterceptorIndex = -1;
protected ReflectiveMethodInvocation(
Object proxy, Object target, Method method, Object[] arguments,
Class<?> targetClass, List<Object> interceptorsAndDynamicMethodMatchers) {
this.proxy = proxy;
this.target = target;
this.targetClass = targetClass;
this.method = BridgeMethodResolver.findBridgedMethod(method);
this.arguments = AopProxyUtils.adaptArgumentsIfNecessary(method, arguments);
this.interceptorsAndDynamicMethodMatchers = interceptorsAndDynamicMethodMatchers;
}
@Override
public Object proceed() throws Throwable {
if (this.currentInterceptorIndex == this.interceptorsAndDynamicMethodMatchers.size() - 1) {
// 执行CglibMethodInvocation的invokeJoinpoint方法
return invokeJoinpoint();
}
Object interceptorOrInterceptionAdvice =
this.interceptorsAndDynamicMethodMatchers.get(++this.currentInterceptorIndex);
if (interceptorOrInterceptionAdvice instanceof InterceptorAndDynamicMethodMatcher) {
InterceptorAndDynamicMethodMatcher dm =
(InterceptorAndDynamicMethodMatcher) interceptorOrInterceptionAdvice;
if (dm.methodMatcher.matches(this.method, this.targetClass, this.arguments)) {
return dm.interceptor.invoke(this);
}
else {
return proceed();
}
}
else {
return ((MethodInterceptor) interceptorOrInterceptionAdvice).invoke(this);
}
}
}
- ReflectiveMethodInvocation负责先执行拦截器，最后调用执行被调用的方法。
- CglibMethodInvocation#invokeJoinpoint方法执行被代理方法。
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