一、动态 AOP 使用示例 1. 创建用于拦截的 bean 创建用于拦截的 bean
1 2 3 4 5 6 7 8 9 10 public class TestBean { private String testStr = "testStr" ; public void testAop () { System.out.println("I am the true aop bean" ); } }
2.创建 Advisor 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 @Aspect public class TestBeanAspect { @Pointcut("execution(* *.testAop(..))") public void test () { } @Before("test()") public void beforeTest () { System.out.println("beforeTest" ); } @After("test()") public void afterTest () { System.out.println("afterTest" ); } @Around("test()") public Object aroundTest (ProceedingJoinPoint p) { System.out.println("brfore around" ); Object o = null ; try { o = p.proceed(); } catch (Throwable e) { e.printStackTrace(); } System.out.println("after around" ); return o; } }
3.创建配置文件
4.测试 1 2 3 4 5 6 @Test public void testAop() { ApplicationContext ctx = new ClassPathXmlApplicationContext("aop/TestBeanAspect.xml"); TestBean bean = (TestBean) ctx.getBean("testBean"); bean.testAop(); }
输出日志：
1 2 3 4 5 brfore around beforeTest I am the true aop bean after around afterTest
二、基本概念与相关类图 1.基本概念 参考：
基本概念：
Join point: 连接点, 也是关注点，目标对象的目标方法
pointcut: 切点，匹配一系列连接点
Weaving：织入, 对关注点的增强过程叫做织入
Advice：即是增强,包括 Before 、After 等增强
Aspect： 切面,是横切关注点的模块化，包括连接点，切点，增强的一个载体.
Target object: 目标对象
AOP proxy: AOP 代理器，包括JDK动态代理器，和CGLIG 动态代理器
Proxy: 代理对象，由代理器创建的代理对象
简单来讲，整个 aspect 可以描述为:
满足 pointcut 规则的 joinpoint 会被添加相应的 advice 操作
SpringAOP 代理过程：
2.相关类图 参考：
2.1 advisorCreator 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 @startuml interface BeanPostProcessor interface InstantiationAwareBeanPostProcessor extends BeanPostProcessor class ProxyProcessorSupport extends ProxyConfig implements Ordered, BeanClassLoaderAware, AopInfrastructureBean interface SmartInstantiationAwareBeanPostProcessor extends InstantiationAwareBeanPostProcessor abstract class AbstractAutoProxyCreator extends ProxyProcessorSupport implements SmartInstantiationAwareBeanPostProcessor, BeanFactoryAware class BeanNameAutoProxyCreator extends AbstractAutoProxyCreator abstract class AbstractAdvisorAutoProxyCreator extends AbstractAutoProxyCreator class InfrastructureAdvisorAutoProxyCreator extends AbstractAdvisorAutoProxyCreator class DefaultAdvisorAutoProxyCreator extends AbstractAdvisorAutoProxyCreator class AspectJAwareAdvisorAutoProxyCreator extends AbstractAdvisorAutoProxyCreator class AnnotationAwareAspectJAutoProxyCreator extends AspectJAwareAdvisorAutoProxyCreator @enduml
AbstractAutoProxyCreator: Spring 为Spring AOP 模块暴露的可扩展抽象类，也是 AOP 中最核心的抽象类
AbstractAdvisorAutoProxyCreator: 扫描所有类，判断是否可以被代理，并寻找合适的增强类，以及生成代理类
AnnotationAwareAspectJAutoProxyCreator: 开启AOP功能后，该类会扫描所有@Aspect注释的类，生成对应的adviosr
2.2 advisor 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 @startuml interface PointcutAdvisor extends Advisor , Ordered abstract class StaticMethodMatcherPointcutAdvisor extends StaticMethodMatcherPointcut implements PointcutAdvisor interface InstantiationModelAwarePointcutAdvisor extends PointcutAdvisor class InstantiationModelAwarePointcutAdvisorImpl implements InstantiationModelAwarePointcutAdvisor abstract class AbstractPointcutAdvisor implements PointcutAdvisor abstract class AbstractGenericPointcutAdvisor extends AbstractPointcutAdvisor class AspectJExpressionPointcutAdvisor extends AbstractGenericPointcutAdvisor implements BeanFactoryAware class RegexpMethodPointcutAdvisor extends AbstractGenericPointcutAdvisor class NameMatchMethodPointcutAdvisor extends AbstractGenericPointcutAdvisor class DefaultPointcutAdvisor extends AbstractGenericPointcutAdvisor @enduml
2.3 advice 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 @startuml interface Interceptor extends Advice interface BeforeAdvice extends Advice interface DynamicIntroductionAdvice extends Advice abstract class AbstractAspectJAdvice implements Advice interface AfterAdvice extends Advice interface MethodInterceptor extends Interceptor interface IntroductionInterceptor extends MethodInterceptor, DynamicIntroductionAdvice class DynamicAdvisedInterceptor implements MethodInterceptor interface MethodBeforeAdvice extends BeforeAdvice class AspectJMethodBeforeAdvice extends AbstractAspectJAdvice implements MethodBeforeAdvice class AspectJAfterAdvice extends AbstractAspectJAdvice implements MethodInterceptor, AfterAdvice @enduml
三、JDK动态代理与CGLIB动态代理 1.代理模式
2.1 JDK动态代理
2.2 CGLIB动态代理 四、AOP 代理对象的创建流程 主要涉及如下流程：
(1) 容器创建过程中，注册或升级 AnnotationAwareAspectJAutoProxyCreator
1.注册或升级 AnnotationAwareAspectJAutoProxyCreator 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 @startuml [-> AspectJAutoProxyBeanDefinitionParser++ :parse AspectJAutoProxyBeanDefinitionParser -> AopNamespaceUtils++ #FFBBBB: registerAspectJAnnotationAutoProxyCreatorIfNecessary AopNamespaceUtils -[#green]> AopConfigUtils++ : 1.registerAspectJAnnotationAutoProxyCreatorIfNecessary AopConfigUtils->AopConfigUtils:registerOrEscalateApcAsRequired AopConfigUtils --> AopNamespaceUtils deactivate AopConfigUtils AopNamespaceUtils -[#green]> AopNamespaceUtils: 2.useClassProxyingIfNecessary AopNamespaceUtils -[#green]> AopNamespaceUtils: 3.registerComponentIfNecessary AopNamespaceUtils --> AspectJAutoProxyBeanDefinitionParser deactivate AopNamespaceUtils [<-- AspectJAutoProxyBeanDefinitionParser @enduml
(1) 注册或升级 AnnotationAwareAspectJAutoProxyCreator 的 BeanDefinition
1.1 AOP 功能的开启 配置文件中的 <aop:aspectj-autoproxy /> 标签开启了AOP功能
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 public class AopNamespaceHandler extends NamespaceHandlerSupport { @Override public void init () { registerBeanDefinitionParser("config" , new ConfigBeanDefinitionParser ()); registerBeanDefinitionParser("aspectj-autoproxy" , new AspectJAutoProxyBeanDefinitionParser ()); registerBeanDefinitionDecorator("scoped-proxy" , new ScopedProxyBeanDefinitionDecorator ()); registerBeanDefinitionParser("spring-configured" , new SpringConfiguredBeanDefinitionParser ()); } }
这个标签的解析器为 AspectJAutoProxyBeanDefinitionParser
2.创建AOP代理 在容器创建过程中，注册了 AnnotationAwareAspectJAutoProxyCreator 的 BeanDefinition, 而在后续加载这个Bean时，由于此Bean实现了 BeanPostProcessor，因此会在其实例化时，调用其 postProcessAfterInstantiation 方法。
AbstractApplicationContext.refresh() -> finishBeanFactoryInitialization()
DefaultListableBeanFactory.preInstantiateSingletons() -> getBean() -> doGetBean()
AbstractAutowireCapableBeanFactory.createBean() -> doCreateBean() -> initializeBean() -> applyBeanPostProcessorsAfterInitialization()
BeanPostProcessor.postProcessAfterInitialization()
也就是说AOP代理创建的入口为 AnnotationAwareAspectJAutoProxyCreator父类AbstractAutoProxyCreator的postProcessAfterInitialization 方法
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 @startuml [-> AbstractAutoProxyCreator++ :postProcessAfterInitialization AbstractAutoProxyCreator -> AbstractAutoProxyCreator: getCacheKey AbstractAutoProxyCreator -> AbstractAutoProxyCreator++: wrapIfNecessary AbstractAutoProxyCreator -> AbstractAdvisorAutoProxyCreator++:1.getAdvicesAndAdvisorsForBean AbstractAdvisorAutoProxyCreator -> AbstractAdvisorAutoProxyCreator++: findEligibleAdvisors AbstractAdvisorAutoProxyCreator -> AnnotationAwareAspectJAutoProxyCreator++: findCandidateAdvisors AnnotationAwareAspectJAutoProxyCreator -> BeanFactoryAspectJAdvisorsBuilder++: buildAspectJAdvisors BeanFactoryAspectJAdvisorsBuilder -> ReflectiveAspectJAdvisorFactory++:getAdvisors return return return AbstractAdvisorAutoProxyCreator -> AbstractAdvisorAutoProxyCreator++: findAdvisorsThatCanApply AbstractAdvisorAutoProxyCreator -> AopUtils++:findAdvisorsThatCanApply AopUtils -> AopUtils++: canApply AopUtils -> AopUtils++: canApply deactivate AopUtils deactivate AopUtils return deactivate AbstractAdvisorAutoProxyCreator deactivate AbstractAdvisorAutoProxyCreator return AbstractAutoProxyCreator -> AbstractAutoProxyCreator++:2.createProxy AbstractAutoProxyCreator -> ProxyFactory++:getProxy ProxyFactory -> AopProxy++: getProxy AopProxy --> ProxyFactory deactivate AopProxy ProxyFactory --> AbstractAutoProxyCreator deactivate AbstractAutoProxyCreator deactivate AbstractAutoProxyCreator [<-- AbstractAutoProxyCreator @enduml
(1) 获取符合条件的增强
