Spring AOP源碼實現分步解析
1 概述
1.1 示例
最基本的使用，在建立了業務接口和實現類後，經過配置<aop:config>....</aop:config>標籤來指定<aop:pointcut和<aop:advisor。示例以下：php
1.1.1 建立接口及實現類
接口：java
public interface MockService {
public String hello(String s);
}
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實現類：spring
public class MockServiceImpl implements MockService {
@Override
public String hello(String s) {
System.out.println("execute hello");
return s;
}
}
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1.1.2 實現方法攔截
實現接口org.aopalliance.intercept.MethodInterceptorexpress
public class CustomInterceptor implements MethodInterceptor {
@Override
public Object invoke(MethodInvocation invocation) throws Throwable {
System.out.println("CustomInterceptor before");
Object result = invocation.proceed();
System.out.println("CustomInterceptor after");
return result;
}
}
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1.1.3 配置xml
建立aop.xml，放在resources目錄下：數組
<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans" xmlns:aop="http://www.springframework.org/schema/aop" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-2.5.xsd http://www.springframework.org/schema/aop http://www.springframework.org/schema/aop/spring-aop-2.5.xsd" default-lazy-init="false" default-autowire="byName">
<!-- 實現來org.aopalliance.intercept.MethodInterceptor的攔截器 -->
<bean id="customInterceptor" class="com.xxx.yyy.CustomInterceptor"/>
<bean id="mockService" class="com.xxx.yyy.MockServiceImpl"/>
<aop:config proxy-target-class="true">
<aop:pointcut id="interceptorPointCuts" expression="execution(* com.xxx.yyy..*.*(..))"/>
<aop:advisor advice-ref="customInterceptor" pointcut-ref="interceptorPointCuts"/>
</aop:config>
</beans>
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1.1.4 運行
public class Main {
public static void main(String[] args){
ApplicationContext context = new ClassPathXmlApplicationContext("aop.xml");
MockService mockService = (MockService) context.getBean("mockService");
mockService.hello("mock");
}
}
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返回：bash
CustomInterceptor before
execute hello
CustomInterceptor after
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1.2 AOP實現過程
Spring環境啓動過程當中，會調用AbstractApplicationContext.refresh()，AOP的實現流程，也就是從這裏開始。app
- 1 在
obtainFreshBeanFactory()執行過程當中，加載aop.xml，並根據namespace找到aop對應的NamespaceHandler：AopNamespaceHandler； - 2
AopNamespaceHandler中，找到config標籤對應的BeanDefinitionParser的實現對象，也就是ConfigBeanDefinitionParser； - 3 執行
ConfigBeanDefinitionParser.parse，有兩個做用：- 以
AspectJAwareAdvisorAutoProxyCreator註冊BeanDefinition； - 解析
pointcut，advisor等標籤，並將相關對象註冊爲BeanDefinition。
- 以
- 4 註冊BeanPostProcessor：
AspectJAwareAdvisorAutoProxyCreator是BeanPostProcessor的實現類AbstractAutoProxyCreator的子類。註冊BeanPostProcessor後，AspectJAwareAdvisorAutoProxyCreator會在Spring建立bean的代理過程當中調用。 - 5 建立proxy，並用advisor加強，主要有幾步：
- 建立代理；
- 查找匹配的advisor；
- 加強代理。
2 AopNamespaceHandler
Spring環境的加載，須要調用AbstractApplicationContext.refresh()。ide
在refresh()方法中，執行ConfigurableListableBeanFactory beanFactory = obtainFreshBeanFactory();建立BeanFacotry的時候，加載並解析xml資源。post
在這個過程當中，會調用BeanDefinitionParserDelegate.parseCustomElement進行擴展標籤的解析:ui
public BeanDefinition parseCustomElement(Element ele, BeanDefinition containingBd) {
// 獲取namespace
String namespaceUri = getNamespaceURI(ele);
// 根據文件META-INF/spring.handlers，獲取對應的NamespaceHandler
NamespaceHandler handler = this.readerContext.getNamespaceHandlerResolver().resolve(namespaceUri);
if (handler == null) {
error("Unable to locate Spring NamespaceHandler for XML schema namespace [" + namespaceUri + "]", ele);
return null;
}
// 調用NamespaceHandler.parse方法，返回BeanDefinition
return handler.parse(ele, new ParserContext(this.readerContext, this, containingBd));
}
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詳細過程可參考Spring自定義標籤配置的源碼解析與實現。
對於<aop:config/>，Spring會根據xmlns去META-INF/spring.handlers文件中查找相應的namespace解析類： http\://www.springframework.org/schema/aop=org.springframework.aop.config.AopNamespaceHandler。
在AopNamespaceHandler中： registerBeanDefinitionParser("config", new ConfigBeanDefinitionParser());
因此：
aopnamespace的解析類是AopNamespaceHandler<aop:config/>標籤的解析類是ConfigBeanDefinitionParser，在ConfigBeanDefinitionParser中，<aop:config/>定義的各個元素被解析爲BeanDefinition。
3 ConfigBeanDefinitionParser
ConfigBeanDefinitionParser實現了BeanDefinitionParser接口，在parse(Element element, ParserContext parserContext)方法中，實現了兩部分功能：
- 1 向Spring環境註冊一個BeanDefinition：
AspectJAwareAdvisorAutoProxyCreator； - 2 將xml配置的pointcut，advisor等解析爲一系列BeanDefinition。
@Override
@Nullable
public BeanDefinition parse(Element element, ParserContext parserContext) {
CompositeComponentDefinition compositeDef =
new CompositeComponentDefinition(element.getTagName(), parserContext.extractSource(element));
parserContext.pushContainingComponent(compositeDef);
// 註冊AspectJAwareAdvisorAutoProxyCreator爲BeanDefinition
configureAutoProxyCreator(parserContext, element);
List<Element> childElts = DomUtils.getChildElements(element);
for (Element elt: childElts) {
String localName = parserContext.getDelegate().getLocalName(elt);
if (POINTCUT.equals(localName)) {
// 解析pointcut
parsePointcut(elt, parserContext);
}
else if (ADVISOR.equals(localName)) {
// 解析advisor
parseAdvisor(elt, parserContext);
}
else if (ASPECT.equals(localName)) {
parseAspect(elt, parserContext);
}
}
parserContext.popAndRegisterContainingComponent();
return null;
}
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其中：
private static final String POINTCUT = "pointcut";
private static final String ADVISOR = "advisor";
private static final String ASPECT = "aspect";
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3.1 AspectJAwareAdvisorAutoProxyCreator
3.1.1 做用
AspectJAwareAdvisorAutoProxyCreator是AbstractAutoProxyCreator的子類;- AbstractAutoProxyCreator實現了接口
BeanPostProcessor; - AbstractAutoProxyCreator在
postProcessAfterInitialization的實現中，調用wrapIfNecessary進行bean代理。
@Override
public Object postProcessAfterInitialization(@Nullable Object bean, String beanName) throws BeansException {
if (bean != null) {
Object cacheKey = getCacheKey(bean.getClass(), beanName);
if (!this.earlyProxyReferences.contains(cacheKey)) {
return wrapIfNecessary(bean, beanName, cacheKey);
}
}
return bean;
}
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Spring在實例化bean的過程當中，會調用BeanPostProcessor對bean生成先後進行處理，aop利用這一點：
調用AbstractAutoProxyCreator.postProcessAfterInitialization方法，根據pointcut查找到相應的advisor，對bean進行代理。
3.1.2 註冊BeanDefinition
代碼執行流程：
-
1 ConfigBeanDefinitionParser.configureAutoProxyCreator;
-
2 AopNamespaceUtils.registerAspectJAutoProxyCreatorIfNecessary(parserContext, element);
public static void registerAspectJAutoProxyCreatorIfNecessary( ParserContext parserContext, Element sourceElement) { // 註冊BeanDefinition BeanDefinition beanDefinition = AopConfigUtils.registerAspectJAutoProxyCreatorIfNecessary( parserContext.getRegistry(), parserContext.extractSource(sourceElement)); // 設置class-proxy useClassProxyingIfNecessary(parserContext.getRegistry(), sourceElement); registerComponentIfNecessary(beanDefinition, parserContext); } 複製代碼 -
3 AopConfigUtils.registerAspectJAutoProxyCreatorIfNecessary;
-
4 AopConfigUtils.registerOrEscalateApcAsRequired:
public static final String AUTO_PROXY_CREATOR_BEAN_NAME =
"org.springframework.aop.config.internalAutoProxyCreator";
RootBeanDefinition beanDefinition = new RootBeanDefinition(cls);
//// 省略代碼
registry.registerBeanDefinition(AUTO_PROXY_CREATOR_BEAN_NAME, beanDefinition);
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最終生成了
AspectJAwareAdvisorAutoProxyCreator的BeanDefinition，beanName爲org.springframework.aop.config.internalAutoProxyCreator。同時，
useClassProxyingIfNecessary方法中，根據**aop:config/**中的proxy-target-class，設置了AspectJAwareAdvisorAutoProxyCreator的一個父類ProxyConfig的proxyTargetClass屬性。
3.2 解析pointcut
解析<aop:pointcut id="interceptorPointCuts" expression="execution(* com.xxx.yyy..*.*(..))"/>，註冊AbstractExpressionPointcut的BeanDefinition。
3.2.1 parsePointcut
private AbstractBeanDefinition parsePointcut(Element pointcutElement, ParserContext parserContext) {
String id = pointcutElement.getAttribute(ID);
// 獲取表達式 配置中的 expression="execution(* com.xxx.yyy..*.*(..))"
String expression = pointcutElement.getAttribute(EXPRESSION);
AbstractBeanDefinition pointcutDefinition = null;
try {
this.parseState.push(new PointcutEntry(id));
// 使用AspectJExpressionPointcut，爲pointcut建立BeanDefinition，
pointcutDefinition = createPointcutDefinition(expression);
pointcutDefinition.setSource(parserContext.extractSource(pointcutElement));
String pointcutBeanName = id;
if (StringUtils.hasText(pointcutBeanName)) {
// 以id爲beanName註冊AspectJExpressionPointcut爲bean.
parserContext.getRegistry().registerBeanDefinition(pointcutBeanName, pointcutDefinition);
}
else {
// 自動生成beanName註冊AspectJExpressionPointcut爲bean.
pointcutBeanName = parserContext.getReaderContext().registerWithGeneratedName(pointcutDefinition);
}
parserContext.registerComponent(
new PointcutComponentDefinition(pointcutBeanName, pointcutDefinition, expression));
}
finally {
this.parseState.pop();
}
return pointcutDefinition;
}
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3.2.2 createPointcutDefinition
- 1
aop:pointcut解析爲AspectJExpressionPointcut對象。 - 2
AspectJExpressionPointcut extends AbstractExpressionPointcut - 3
expression是AbstractExpressionPointcut的屬性
protected AbstractBeanDefinition createPointcutDefinition(String expression) {
RootBeanDefinition beanDefinition = new RootBeanDefinition(AspectJExpressionPointcut.class);
beanDefinition.setScope(BeanDefinition.SCOPE_PROTOTYPE);
beanDefinition.setSynthetic(true);
beanDefinition.getPropertyValues().add(EXPRESSION, expression);
return beanDefinition;
}
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3.3 解析advisor
解析<aop:advisor advice-ref="customInterceptor" pointcut-ref="interceptorPointCuts"/>，註冊DefaultBeanFactoryPointcutAdvisor的BeanDefinition。
3.3.1 parseAdvisor
- 1 調用
createAdvisorBeanDefinition建立advisor； - 2 調用
parsePointcutProperty獲取pointcut。
private void parseAdvisor(Element advisorElement, ParserContext parserContext) {
// 1 建立bean : DefaultBeanFactoryPointcutAdvisor
AbstractBeanDefinition advisorDef = createAdvisorBeanDefinition(advisorElement, parserContext);
String id = advisorElement.getAttribute(ID);
try {
this.parseState.push(new AdvisorEntry(id));
String advisorBeanName = id;
// 2 註冊bean : DefaultBeanFactoryPointcutAdvisor
if (StringUtils.hasText(advisorBeanName)) {
parserContext.getRegistry().registerBeanDefinition(advisorBeanName, advisorDef);
}
else {
advisorBeanName = parserContext.getReaderContext().registerWithGeneratedName(advisorDef);
}
// 3 解析 pointcut-ref="interceptorPointCuts"
Object pointcut = parsePointcutProperty(advisorElement, parserContext);
if (pointcut instanceof BeanDefinition) {
// 返回的是有`pointcut`構造的BeanDefinition(AspectJExpressionPointcut對象)，則設置`DefaultBeanFactoryPointcutAdvisor.pointcut = pointcut`
advisorDef.getPropertyValues().add(POINTCUT, pointcut);
parserContext.registerComponent(
new AdvisorComponentDefinition(advisorBeanName, advisorDef, (BeanDefinition) pointcut));
}
else if (pointcut instanceof String) {
// 返回的是beanName，則設置`DefaultBeanFactoryPointcutAdvisor.pointcut`爲一個運行時Bean引用。
advisorDef.getPropertyValues().add(POINTCUT, new RuntimeBeanReference((String) pointcut));
parserContext.registerComponent(
new AdvisorComponentDefinition(advisorBeanName, advisorDef));
}
}
finally {
this.parseState.pop();
}
}
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3.3.2 createAdvisorBeanDefinition
- 1 建立
DefaultBeanFactoryPointcutAdvisor的BeanDefinition，DefaultBeanFactoryPointcutAdvisor是PointcutAdvisor的一個實現； - 2 解析
advice-ref獲取advisor的Bean的beanName，即aop.xml中的customInterceptor。 - 3
DefaultBeanFactoryPointcutAdvisor extends AbstractBeanFactoryPointcutAdvisor，使用advice-ref設置adviceBeanName屬性，即前面的customInterceptor。
private static final String ADVICE_BEAN_NAME = "adviceBeanName";
private AbstractBeanDefinition createAdvisorBeanDefinition(Element advisorElement, ParserContext parserContext) {
// 建立`DefaultBeanFactoryPointcutAdvisor`的BeanDefinition；
RootBeanDefinition advisorDefinition = new RootBeanDefinition(DefaultBeanFactoryPointcutAdvisor.class);
advisorDefinition.setSource(parserContext.extractSource(advisorElement));
// 解析`advice-ref`獲取advice的Bean的beanName；
String adviceRef = advisorElement.getAttribute(ADVICE_REF);
if (!StringUtils.hasText(adviceRef)) {
parserContext.getReaderContext().error(
"'advice-ref' attribute contains empty value.", advisorElement, this.parseState.snapshot());
}
else {
// 設置AbstractBeanFactoryPointcutAdvisor的adviceBeanName屬性
advisorDefinition.getPropertyValues().add(
ADVICE_BEAN_NAME, new RuntimeBeanNameReference(adviceRef));
}
if (advisorElement.hasAttribute(ORDER_PROPERTY)) {
advisorDefinition.getPropertyValues().add(
ORDER_PROPERTY, advisorElement.getAttribute(ORDER_PROPERTY));
}
return advisorDefinition;
}
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3.3.3 parsePointcutProperty
- 1 屬性有
pointcut，則使用expression調用createPointcutDefinition，構造AspectJExpressionPointcut的bean後直接返回。 - 2 不然返回
pointcut-ref指定的bean做爲Pointcut。
因此：pointcut優先於 pointcut-ref，有pointcut就再也不解析pointcut-ref。
private Object parsePointcutProperty(Element element, ParserContext parserContext) {
if (element.hasAttribute(POINTCUT) && element.hasAttribute(POINTCUT_REF)) {
parserContext.getReaderContext().error(
"Cannot define both 'pointcut' and 'pointcut-ref' on <advisor> tag.",
element, this.parseState.snapshot());
return null;
}
else if (element.hasAttribute(POINTCUT)) {
// 屬性有`pointcut`，則使用expression調用createPointcutDefinition，構造AspectJExpressionPointcut的bean後直接返回。
String expression = element.getAttribute(POINTCUT);
AbstractBeanDefinition pointcutDefinition = createPointcutDefinition(expression);
pointcutDefinition.setSource(parserContext.extractSource(element));
// 返回BeanDefinition
return pointcutDefinition;
}
else if (element.hasAttribute(POINTCUT_REF)) {
String pointcutRef = element.getAttribute(POINTCUT_REF);
if (!StringUtils.hasText(pointcutRef)) {
parserContext.getReaderContext().error(
"'pointcut-ref' attribute contains empty value.", element, this.parseState.snapshot());
return null;
}
// 返回pointcut-ref的beanName
return pointcutRef;
}
else {
parserContext.getReaderContext().error(
"Must define one of 'pointcut' or 'pointcut-ref' on <advisor> tag.",
element, this.parseState.snapshot());
return null;
}
}
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3.4 解析過程當中註冊的BeanDefinition
- BeanPostProcessor :
AspectJAwareAdvisorAutoProxyCreator，beanName是org.springframework.aop.config.internalAutoProxyCreator； - pointcut：
AbstractExpressionPointcut，設置了expression屬性； - advisor：
DefaultBeanFactoryPointcutAdvisor，pointcut屬性設置爲AbstractExpressionPointcut。
4 註冊BeanPostProcessor
在AbstractApplicationContext.refresh()方法中，建立ConfigurableListableBeanFactory後，會執行registerBeanPostProcessors向Spring環境註冊BeanPostProcessor。
// Register bean processors that intercept bean creation.
registerBeanPostProcessors(beanFactory);
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AspectJAwareAdvisorAutoProxyCreator在這個時候被加入到用於處理bean建立的BeanPostProcessor列表中。
簡要過程以下：
- 1 調用
PostProcessorRegistrationDelegate.registerBeanPostProcessors； - 2 經過
beanFactory.getBean(ppName, BeanPostProcessor.class);獲取BeanPostProcessor列表； - 3 執行
beanFactory.addBeanPostProcessor(postProcessor)。
5 建立Bean並加強
5.1 createProxy
Spring建立Bean，是在AbstractAutowireCapableBeanFactory.doCreateBean方法中：
- 在
AbstractAutowireCapableBeanFactory.doCreateBean中調用了initializeBean：
// Initialize the bean instance.
Object exposedObject = bean;
try {
populateBean(beanName, mbd, instanceWrapper);
exposedObject = initializeBean(beanName, exposedObject, mbd);
}
catch (Throwable ex) {
if (ex instanceof BeanCreationException && beanName.equals(((BeanCreationException) ex).getBeanName())) {
throw (BeanCreationException) ex;
}
else {
throw new BeanCreationException(
mbd.getResourceDescription(), beanName, "Initialization of bean failed", ex);
}
}
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- 在
initializeBean中：
if (mbd == null || !mbd.isSynthetic()) {
wrappedBean = applyBeanPostProcessorsAfterInitialization(wrappedBean, beanName);
}
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applyBeanPostProcessorsAfterInitialization執行了BeanPostProcessor.postProcessAfterInitialization方法：
@Override
public Object applyBeanPostProcessorsAfterInitialization(Object existingBean, String beanName) throws BeansException {
Object result = existingBean;
for (BeanPostProcessor beanProcessor : getBeanPostProcessors()) {
Object current = beanProcessor.postProcessAfterInitialization(result, beanName);
if (current == null) {
return result;
}
result = current;
}
return result;
}
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AbstractAutoProxyCreator.postProcessAfterInitialization就在這裏執行：
@Override
public Object postProcessAfterInitialization(@Nullable Object bean, String beanName) throws BeansException {
if (bean != null) {
Object cacheKey = getCacheKey(bean.getClass(), beanName);
if (!this.earlyProxyReferences.contains(cacheKey)) {
return wrapIfNecessary(bean, beanName, cacheKey);
}
}
return bean;
}
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- 在
wrapIfNecessary中使用advisor執行createProxy：
// Create proxy if we have advice.
// 1 查找advisor
Object[] specificInterceptors = getAdvicesAndAdvisorsForBean(bean.getClass(), beanName, null);
if (specificInterceptors != DO_NOT_PROXY) {
this.advisedBeans.put(cacheKey, Boolean.TRUE);
// 2 建立proxy，並使用advisor進行加強
Object proxy = createProxy(
bean.getClass(), beanName, specificInterceptors, new SingletonTargetSource(bean));
this.proxyTypes.put(cacheKey, proxy.getClass());
return proxy;
}
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5.2 查找匹配的advisor
AbstractAutoProxyCreator.getAdvicesAndAdvisorsForBean是一個抽象方法，由子類AbstractAdvisorAutoProxyCreator實現。
AbstractAdvisorAutoProxyCreator.getAdvicesAndAdvisorsForBean調用了findEligibleAdvisors，主要實現兩個流程：
- 1 獲取候選的advisors；
- 2 過濾出匹配的advisors。
/* beanClass:要代理的類 beanName:當前要代理的bean的beanName */
protected List<Advisor> findEligibleAdvisors(Class<?> beanClass, String beanName) {
// 1 獲取候選的advisors
List<Advisor> candidateAdvisors = findCandidateAdvisors();
// 2 過濾出匹配的advisors
List<Advisor> eligibleAdvisors = findAdvisorsThatCanApply(candidateAdvisors, beanClass, beanName);
extendAdvisors(eligibleAdvisors);
if (!eligibleAdvisors.isEmpty()) {
eligibleAdvisors = sortAdvisors(eligibleAdvisors);
}
return eligibleAdvisors;
}
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5.2.1 findCandidateAdvisors
調用BeanFactoryAdvisorRetrievalHelper.findAdvisorBeans，獲取到全部實現了Advisor接口的Bean，主要代碼片斷以下：
-
1 找到是有實現了Advisor接口的beanName：
advisorNames = BeanFactoryUtils.beanNamesForTypeIncludingAncestors( this.beanFactory, Advisor.class, true, false); -
2 根據beanName獲取Bean：
List<Advisor> advisors = new LinkedList<>(); .... advisors.add(this.beanFactory.getBean(name, Advisor.class)); .... return advisors; 複製代碼
5.2.2 findAdvisorsThatCanApply
過濾出匹配的Advisor，主要經過AopUtils.findAdvisorsThatCanApply，調用canApply實現：
public static List<Advisor> findAdvisorsThatCanApply(List<Advisor> candidateAdvisors, Class<?> clazz) {
if (candidateAdvisors.isEmpty()) {
return candidateAdvisors;
}
List<Advisor> eligibleAdvisors = new LinkedList<>();
for (Advisor candidate : candidateAdvisors) {
// 調用 canApply
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;
}
// 調用canApply
if (canApply(candidate, clazz, hasIntroductions)) {
eligibleAdvisors.add(candidate);
}
}
return eligibleAdvisors;
}
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5.2.3 canApply
- 1 若是接口是
IntroductionAdvisor，則調用IntroductionAdvisor.ClassFilter.matchs進行判斷； - 2 若是接口是
PointcutAdvisor(好比前面建立的DefaultBeanFactoryPointcutAdvisor)，則先調用PointcutAdvisor.ClassFilter.matches進行判斷，再MethodMatcher.getMethodMatcher()進行判斷。
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 {
// It doesn't have a pointcut so we assume it applies.
return true;
}
}
public static boolean canApply(Pointcut pc, Class<?> targetClass, boolean hasIntroductions) {
Assert.notNull(pc, "Pointcut must not be null");
if (!pc.getClassFilter().matches(targetClass)) {
return false;
}
MethodMatcher methodMatcher = pc.getMethodMatcher();
if (methodMatcher == MethodMatcher.TRUE) {
// No need to iterate the methods if we're matching any method anyway...
return true;
}
IntroductionAwareMethodMatcher introductionAwareMethodMatcher = null;
if (methodMatcher instanceof IntroductionAwareMethodMatcher) {
introductionAwareMethodMatcher = (IntroductionAwareMethodMatcher) methodMatcher;
}
Set<Class<?>> classes = new LinkedHashSet<>(ClassUtils.getAllInterfacesForClassAsSet(targetClass));
classes.add(targetClass);
for (Class<?> clazz : classes) {
Method[] methods = ReflectionUtils.getAllDeclaredMethods(clazz);
for (Method method : methods) {
if ((introductionAwareMethodMatcher != null &&
introductionAwareMethodMatcher.matches(method, targetClass, hasIntroductions)) ||
methodMatcher.matches(method, targetClass)) {
return true;
}
}
}
return false;
}
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5.3 使用advisor加強代理
在AbstractAutoProxyCreator.createProxy中實現：
- 1 建立ProxyFactory
- 2 判斷proxyTargetClass
- 3 buildAdvisors
- 4 執行getProxy
protected Object createProxy(Class<?> beanClass, @Nullable String beanName, @Nullable Object[] specificInterceptors, TargetSource targetSource) {
if (this.beanFactory instanceof ConfigurableListableBeanFactory) {
AutoProxyUtils.exposeTargetClass((ConfigurableListableBeanFactory) this.beanFactory, beanName, beanClass);
}
// 建立ProxyFactory
ProxyFactory proxyFactory = new ProxyFactory();
proxyFactory.copyFrom(this);
// 判斷proxyTargetClass
if (!proxyFactory.isProxyTargetClass()) {
if (shouldProxyTargetClass(beanClass, beanName)) {
proxyFactory.setProxyTargetClass(true);
}
else {
evaluateProxyInterfaces(beanClass, proxyFactory);
}
}
// buildAdvisors
Advisor[] advisors = buildAdvisors(beanName, specificInterceptors);
proxyFactory.addAdvisors(advisors);
proxyFactory.setTargetSource(targetSource);
customizeProxyFactory(proxyFactory);
proxyFactory.setFrozen(this.freezeProxy);
if (advisorsPreFiltered()) {
proxyFactory.setPreFiltered(true);
}
// 執行getProxy
return proxyFactory.getProxy(getProxyClassLoader());
}
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5.3.1 DefaultAopProxyFactory.createAopProxy
proxyFactory.getProxy中，須要一個AopProxy去實現，AopProxy的建立，在DefaultAopProxyFactory中，返回一個JdkDynamicAopProxy或一個CglibAopProxy。
@Override
public AopProxy createAopProxy(AdvisedSupport config) throws AopConfigException {
if (config.isOptimize() || config.isProxyTargetClass() || hasNoUserSuppliedProxyInterfaces(config)) {
Class<?> targetClass = config.getTargetClass();
if (targetClass == null) {
throw new AopConfigException("TargetSource cannot determine target class: " +
"Either an interface or a target is required for proxy creation.");
}
if (targetClass.isInterface() || Proxy.isProxyClass(targetClass)) {
return new JdkDynamicAopProxy(config);
}
return new ObjenesisCglibAopProxy(config);
}
else {
return new JdkDynamicAopProxy(config);
}
}
複製代碼
5.3.2 JdkDynamicAopProxy
JdkDynamicAopProxy實現了java.lang.reflect.InvocationHandler接口，在invoke(Object proxy, Method method, Object[] args)中實現代理。代碼片斷以下：
// Get the interception chain for this method.
List<Object> chain = this.advised.getInterceptorsAndDynamicInterceptionAdvice(method, targetClass);
// Check whether we have any advice. If we don't, we can fallback on direct
// reflective invocation of the target, and avoid creating a MethodInvocation.
if (chain.isEmpty()) {
// We can skip creating a MethodInvocation: just invoke the target directly
// Note that the final invoker must be an InvokerInterceptor so we know it does
// nothing but a reflective operation on the target, and no hot swapping or fancy proxying.
Object[] argsToUse = AopProxyUtils.adaptArgumentsIfNecessary(method, args);
retVal = AopUtils.invokeJoinpointUsingReflection(target, method, argsToUse);
}
else {
// We need to create a method invocation...
invocation = new ReflectiveMethodInvocation(proxy, target, method, args, targetClass, chain);
// Proceed to the joinpoint through the interceptor chain.
retVal = invocation.proceed();
}
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調用
ReflectiveMethodInvocation.proceed()實現了代理。
5.3.3 ObjenesisCglibAopProxy
ObjenesisCglibAopProxy是CglibAopProxy的子類，代理邏輯都實如今CglibAopProxy裏。
CglibAopProxy中獲取Callback數組時，建立了DynamicAdvisedInterceptor對象。
private Callback[] getCallbacks(Class<?> rootClass){
//省略代碼
// Choose an "aop" interceptor (used for AOP calls).
Callback aopInterceptor = new DynamicAdvisedInterceptor(this.advised);
//省略代碼
}
複製代碼
DynamicAdvisedInterceptor實現了org.springframework.cglib.proxy.MethodInterceptor接口，在intercept方法裏執行了代理：
// We need to create a method invocation...
retVal = new CglibMethodInvocation(proxy, target, method, args, targetClass, chain, methodProxy).proceed();
複製代碼
CglibMethodInvocation是
ReflectiveMethodInvocation的子類，因此也是調用ReflectiveMethodInvocation.proceed()實現了代理。
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