SpringAOP模拟实现

文章目录

- 1_底层切点、通知、切面
- 2_切点匹配
- 3_从 @Aspect 到 Advisor
- - 1_代理创建器
  - 2_代理创建时机
  - 3_@Before 对应的低级通知
- 4_静态通知调用
- - 1_通知调用过程
  - 2_模拟 MethodInvocation
- 5_动态通知调用

1_底层切点、通知、切面

注意点：

底层的切点实现
底层的通知实现
底层的切面实现
ProxyFactory 用来创建代理
- 如果指定了接口，且 proxyTargetClass = false，使用 JdkDynamicAopProxy
- 如果没有指定接口，或者 proxyTargetClass = true，使用 ObjenesisCglibAopProxy
- 例外：如果目标是接口类型或已经是 jdk 代理，使用 JdkDynamicAopProxy

public class A15 {public static void main(String[] args) {/*两个切面概念aspect =通知1(advice) +  切点1(pointcut)通知2(advice) +  切点2(pointcut)通知3(advice) +  切点3(pointcut)...advisor = 更细粒度的切面，包含一个通知和切点*/// 1. 备好切点AspectJExpressionPointcut pointcut = new AspectJExpressionPointcut();pointcut.setExpression("execution(* foo())");// 2. 备好通知MethodInterceptor advice = invocation -> {System.out.println("before...");Object result = invocation.proceed(); // 调用目标System.out.println("after...");return result;};// 3. 备好切面DefaultPointcutAdvisor advisor = new DefaultPointcutAdvisor(pointcut, advice);/*4. 创建代理a. proxyTargetClass = false, 目标实现了接口, 用 jdk 实现b. proxyTargetClass = false,  目标没有实现接口, 用 cglib 实现c. proxyTargetClass = true, 总是使用 cglib 实现*/Target2 target = new Target2();ProxyFactory factory = new ProxyFactory();factory.setTarget(target);factory.addAdvisor(advisor);factory.setInterfaces(target.getClass().getInterfaces());factory.setProxyTargetClass(false);Target2 proxy = (Target2) factory.getProxy();System.out.println(proxy.getClass());proxy.foo();proxy.bar();/*学到了什么a. Spring 的代理选择规则b. 底层的切点实现c. 底层的通知实现d. ProxyFactory 是用来创建代理的核心实现, 用 AopProxyFactory 选择具体代理实现- JdkDynamicAopProxy- ObjenesisCglibAopProxy*/}interface I1 {void foo();void bar();}static class Target1 implements I1 {public void foo() {System.out.println("target1 foo");}public void bar() {System.out.println("target1 bar");}}static class Target2 {public void foo() {System.out.println("target2 foo");}public void bar() {System.out.println("target2 bar");}}
}

2_切点匹配

切点匹配：

常见 aspectj 切点用法
aspectj 切点的局限性，实际的 @Transactional 切点实现

import org.springframework.aop.aspectj.AspectJExpressionPointcut;
import org.springframework.aop.support.StaticMethodMatcherPointcut;
import org.springframework.core.annotation.MergedAnnotations;
import org.springframework.transaction.annotation.Transactional;import java.lang.reflect.Method;public class A16 {public static void main(String[] args) throws NoSuchMethodException {
//        AspectJExpressionPointcut pt1 = new AspectJExpressionPointcut();
//        pt1.setExpression("execution(* bar())");
//        System.out.println(pt1.matches(T1.class.getMethod("foo"), T1.class));
//        System.out.println(pt1.matches(T1.class.getMethod("bar"), T1.class));
//
//        AspectJExpressionPointcut pt2 = new AspectJExpressionPointcut();
//        pt2.setExpression("@annotation(org.springframework.transaction.annotation.Transactional)");
//        System.out.println(pt2.matches(T1.class.getMethod("foo"), T1.class));
//        System.out.println(pt2.matches(T1.class.getMethod("bar"), T1.class));StaticMethodMatcherPointcut pt3 = new StaticMethodMatcherPointcut() {@Overridepublic boolean matches(Method method, Class<?> targetClass) {// 检查方法上是否加了 Transactional 注解MergedAnnotations annotations = MergedAnnotations.from(method);if (annotations.isPresent(Transactional.class)) {return true;}// 查看类上是否加了 Transactional 注解annotations = MergedAnnotations.from(targetClass, MergedAnnotations.SearchStrategy.TYPE_HIERARCHY);if (annotations.isPresent(Transactional.class)) {return true;}return false;}};System.out.println(pt3.matches(T1.class.getMethod("foo"), T1.class));System.out.println(pt3.matches(T1.class.getMethod("bar"), T1.class));System.out.println(pt3.matches(T2.class.getMethod("foo"), T2.class));System.out.println(pt3.matches(T3.class.getMethod("foo"), T3.class));/*学到了什么a. 底层切点实现是如何匹配的: 调用了 aspectj 的匹配方法b. 比较关键的是它实现了 MethodMatcher 接口, 用来执行方法的匹配*/}static class T1 {@Transactionalpublic void foo() {}public void bar() {}}@Transactionalstatic class T2 {public void foo() {}}@Transactionalinterface I3 {void foo();}static class T3 implements I3 {public void foo() {}}
}

3_从 @Aspect 到 Advisor

1_代理创建器

注意点：

AnnotationAwareAspectJAutoProxyCreator 的作用
- 将高级 @Aspect 切面统一为低级 Advisor 切面。
- 在合适的时机创建代理。
findEligibleAdvisors 找到有【资格】的 Advisors
- 有【资格】的 Advisor 一部分是低级的, 可以由自己编写, 如本例 A17 中的 advisor3。
- 有【资格】的 Advisor 另一部分是高级的, 由解析 @Aspect 后获得。
wrapIfNecessary
- 它内部调用 findEligibleAdvisors, 只要返回集合不空, 则表示需要创建代理。
- 它的调用时机通常在原始对象初始化后执行, 但碰到循环依赖会提前至依赖注入之前执行。

package org.springframework.aop.framework.autoproxy;import org.aopalliance.intercept.MethodInterceptor;
import org.aopalliance.intercept.MethodInvocation;
import org.aspectj.lang.annotation.After;
import org.aspectj.lang.annotation.Aspect;
import org.aspectj.lang.annotation.Before;
import org.springframework.aop.Advisor;
import org.springframework.aop.aspectj.AspectJExpressionPointcut;
import org.springframework.aop.aspectj.annotation.AnnotationAwareAspectJAutoProxyCreator;
import org.springframework.aop.support.DefaultPointcutAdvisor;
import org.springframework.beans.factory.support.DefaultListableBeanFactory;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.context.annotation.ConfigurationClassPostProcessor;
import org.springframework.context.support.GenericApplicationContext;
import org.springframework.transaction.annotation.Transactional;import java.util.List;/*** @author shenyang* @version 1.0* @info TestAop* @since 2024/8/17 20:26*/
public class A17 {@Aspect//高级切面static class Aspect1{@Before("execution(* foo())")public void before(){System.out.println("aspect1 before.....");}@After("execution(* foo())")public void after(){System.out.println("aspect1 after.....");}}@Configurationstatic class Config {@Bean//低级切面public Advisor advisor3(MethodInterceptor advice3) {AspectJExpressionPointcut pointcut = new AspectJExpressionPointcut();pointcut.setExpression("execution(* foo())");return new DefaultPointcutAdvisor(pointcut, advice3);}@Beanpublic MethodInterceptor advice3(){return new MethodInterceptor() {@Overridepublic Object invoke(MethodInvocation methodInvocation) throws Throwable {System.out.println("advice3 before.....");Object proceed = methodInvocation.proceed();System.out.println("advice3 after.....");return proceed;}};}}static class T1 {public void foo() {System.out.println("target1 foo");}}static class T2 {public void bar() {System.out.println("target2 bar");}}public static void main(String[] args) {GenericApplicationContext context = new GenericApplicationContext();context.registerBean("aspect1",Aspect1.class);context.registerBean("config",Config.class);context.registerBean(ConfigurationClassPostProcessor.class);context.registerBean(AnnotationAwareAspectJAutoProxyCreator.class);context.refresh();AnnotationAwareAspectJAutoProxyCreator creator = context.getBean(AnnotationAwareAspectJAutoProxyCreator.class);List<Advisor> advisors = creator.findEligibleAdvisors(T2.class, "target2");System.out.println("====================");
//        advisors.forEach(System.out::println);T1 o1 = (T1) creator.wrapIfNecessary(new T1(), "target1", "target1");T2 o2 = (T2) creator.wrapIfNecessary(new T2(), "target2", "target2");System.out.println(o1.getClass()+" "+o2.getClass());o1.foo();o2.bar();}}

2_代理创建时机

注意点：

代理的创建时机
- 初始化之后 (无循环依赖时)
- 实例创建后, 依赖注入前 (有循环依赖时), 并暂存于二级缓存。
依赖注入与初始化不应该被增强, 仍应被施加于原始对象

package org.springframework.aop.framework.autoproxy;import org.aopalliance.intercept.MethodInterceptor;
import org.aopalliance.intercept.MethodInvocation;
import org.springframework.aop.Advisor;
import org.springframework.aop.aspectj.AspectJExpressionPointcut;
import org.springframework.aop.aspectj.annotation.AnnotationAwareAspectJAutoProxyCreator;
import org.springframework.aop.support.DefaultPointcutAdvisor;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.CommonAnnotationBeanPostProcessor;
import org.springframework.context.annotation.Configuration;
import org.springframework.context.annotation.ConfigurationClassPostProcessor;
import org.springframework.context.support.GenericApplicationContext;import javax.annotation.PostConstruct;public class A17_1 {public static void main(String[] args) {GenericApplicationContext context = new GenericApplicationContext();context.registerBean(ConfigurationClassPostProcessor.class);context.registerBean(Config.class);context.refresh();context.close();// 创建 -> (*) 依赖注入 -> 初始化 (*)/*学到了什么a. 代理的创建时机1. 初始化之后 (无循环依赖时)2. 实例创建后, 依赖注入前 (有循环依赖时), 并暂存于二级缓存b. 依赖注入与初始化不应该被增强, 仍应被施加于原始对象*/}@Configurationstatic class Config {@Bean // 解析 @Aspect、产生代理public AnnotationAwareAspectJAutoProxyCreator annotationAwareAspectJAutoProxyCreator() {return new AnnotationAwareAspectJAutoProxyCreator();}@Bean // 解析 @Autowiredpublic AutowiredAnnotationBeanPostProcessor autowiredAnnotationBeanPostProcessor() {return new AutowiredAnnotationBeanPostProcessor();}@Bean // 解析 @PostConstructpublic CommonAnnotationBeanPostProcessor commonAnnotationBeanPostProcessor() {return new CommonAnnotationBeanPostProcessor();}@Beanpublic Advisor advisor(MethodInterceptor advice) {AspectJExpressionPointcut pointcut = new AspectJExpressionPointcut();pointcut.setExpression("execution(* foo())");return new DefaultPointcutAdvisor(pointcut, advice);}@Beanpublic MethodInterceptor advice() {return (MethodInvocation invocation) -> {System.out.println("before...");return invocation.proceed();};}@Beanpublic Bean1 bean1() {return new Bean1();}@Beanpublic Bean2 bean2() {return new Bean2();}}static class Bean1 {public void foo() {}public Bean1() {System.out.println("Bean1()");}@Autowired public void setBean2(Bean2 bean2) {System.out.println("Bean1 setBean2(bean2) class is: " + bean2.getClass());}@PostConstruct public void init() {System.out.println("Bean1 init()");}}static class Bean2 {public Bean2() {System.out.println("Bean2()");}@Autowired public void setBean1(Bean1 bean1) {System.out.println("Bean2 setBean1(bean1) class is: " + bean1.getClass());}@PostConstruct public void init() {System.out.println("Bean2 init()");}}
}

3_@Before 对应的低级通知

注意点：

@Before 前置通知会被转换为原始的 AspectJMethodBeforeAdvice 形式, 该对象包含了如下信息
- 通知代码从哪儿来
- 切点是什么(这里为啥要切点, 后面解释)
- 通知对象如何创建, 本例共用同一个 Aspect 对象
类似的还有
- AspectJAroundAdvice (环绕通知)
- AspectJAfterReturningAdvice
- AspectJAfterThrowingAdvice (环绕通知)
- AspectJAfterAdvice (环绕通知)

package org.springframework.aop.framework.autoproxy;import org.aspectj.lang.ProceedingJoinPoint;
import org.aspectj.lang.annotation.Before;
import org.springframework.aop.Advisor;
import org.springframework.aop.aspectj.AspectInstanceFactory;
import org.springframework.aop.aspectj.AspectJExpressionPointcut;
import org.springframework.aop.aspectj.AspectJMethodBeforeAdvice;
import org.springframework.aop.aspectj.SingletonAspectInstanceFactory;
import org.springframework.aop.support.DefaultPointcutAdvisor;import java.lang.reflect.Method;
import java.util.ArrayList;
import java.util.List;public class A17_2 {static class Aspect {@Before("execution(* foo())")public void before1() {System.out.println("before1");}@Before("execution(* foo())")public void before2() {System.out.println("before2");}public void after() {System.out.println("after");}public void afterReturning() {System.out.println("afterReturning");}public void afterThrowing() {System.out.println("afterThrowing");}public Object around(ProceedingJoinPoint pjp) throws Throwable {try {System.out.println("around...before");return pjp.proceed();} finally {System.out.println("around...after");}}}static class Target {public void foo() {System.out.println("target foo");}}@SuppressWarnings("all")public static void main(String[] args) throws Throwable {AspectInstanceFactory factory = new SingletonAspectInstanceFactory(new Aspect());// 高级切面转低级切面类List<Advisor> list = new ArrayList<>();for (Method method : Aspect.class.getDeclaredMethods()) {if (method.isAnnotationPresent(Before.class)) {// 解析切点String expression = method.getAnnotation(Before.class).value();AspectJExpressionPointcut pointcut = new AspectJExpressionPointcut();pointcut.setExpression(expression);// 通知类AspectJMethodBeforeAdvice advice = new AspectJMethodBeforeAdvice(method, pointcut, factory);// 切面Advisor advisor = new DefaultPointcutAdvisor(pointcut, advice);list.add(advisor);}}for (Advisor advisor : list) {System.out.println(advisor);}/*@Before 前置通知会被转换为下面原始的 AspectJMethodBeforeAdvice 形式, 该对象包含了如下信息a. 通知代码从哪儿来b. 切点是什么(这里为啥要切点, 后面解释)c. 通知对象如何创建, 本例共用同一个 Aspect 对象类似的通知还有1. AspectJAroundAdvice (环绕通知)2. AspectJAfterReturningAdvice3. AspectJAfterThrowingAdvice4. AspectJAfterAdvice (环绕通知)*/}
}

4_静态通知调用

代理对象调用流程如下（以 JDK 动态代理实现为例）

从 ProxyFactory 获得 Target 和环绕通知链，根据他俩创建 MethodInvocation，简称 mi
首次执行 mi.proceed() 发现有下一个环绕通知，调用它的 invoke(mi)
进入环绕通知1，执行前增强，再次调用 mi.proceed() 发现有下一个环绕通知，调用它的 invoke(mi)
进入环绕通知2，执行前增强，调用 mi.proceed() 发现没有环绕通知，调用 mi.invokeJoinPoint() 执行目标方法
目标方法执行结束，将结果返回给环绕通知2，执行环绕通知2 的后增强
环绕通知2继续将结果返回给环绕通知1，执行环绕通知1 的后增强
环绕通知1返回最终的结果

图中不同颜色对应一次环绕通知或目标的调用起始至终结

1_通知调用过程

代理方法执行时会做如下工作：

通过 proxyFactory 的 getInterceptorsAndDynamicInterceptionAdvice() 将其他通知统一转换为 MethodInterceptor 环绕通知
- MethodBeforeAdviceAdapter 将 @Before AspectJMethodBeforeAdvice 适配为 MethodBeforeAdviceInterceptor
- AfterReturningAdviceAdapter 将 @AfterReturning AspectJAfterReturningAdvice 适配为 AfterReturningAdviceInterceptor
- 这体现的是适配器设计模式
所谓静态通知，体现在上面方法的 Interceptors 部分，这些通知调用时无需再次检查切点，直接调用即可
结合目标与环绕通知链，创建 MethodInvocation 对象，通过它完成整个调用

package org.springframework.aop.framework;import org.aopalliance.intercept.MethodInvocation;
import org.aspectj.lang.ProceedingJoinPoint;
import org.aspectj.lang.annotation.AfterReturning;
import org.aspectj.lang.annotation.AfterThrowing;
import org.aspectj.lang.annotation.Around;
import org.aspectj.lang.annotation.Before;
import org.springframework.aop.Advisor;
import org.springframework.aop.aspectj.*;
import org.springframework.aop.framework.ProxyFactory;
import org.springframework.aop.framework.ReflectiveMethodInvocation;
import org.springframework.aop.interceptor.ExposeInvocationInterceptor;
import org.springframework.aop.support.DefaultPointcutAdvisor;import java.lang.reflect.Method;
import java.util.ArrayList;
import java.util.List;public class A18 {static class Aspect {@Before("execution(* foo())")public void before1() {System.out.println("before1");}@Before("execution(* foo())")public void before2() {System.out.println("before2");}public void after() {System.out.println("after");}@AfterReturning("execution(* foo())")public void afterReturning() {System.out.println("afterReturning");}@AfterThrowing("execution(* foo())")public void afterThrowing(Exception e) {System.out.println("afterThrowing " + e.getMessage());}@Around("execution(* foo())")public Object around(ProceedingJoinPoint pjp) throws Throwable {try {System.out.println("around...before");return pjp.proceed();} finally {System.out.println("around...after");}}}static class Target {public void foo() {System.out.println("target foo");}}@SuppressWarnings("all")public static void main(String[] args) throws Throwable {AspectInstanceFactory factory = new SingletonAspectInstanceFactory(new Aspect());// 1. 高级切面转低级切面类List<Advisor> list = new ArrayList<>();for (Method method : Aspect.class.getDeclaredMethods()) {if (method.isAnnotationPresent(Before.class)) {// 解析切点String expression = method.getAnnotation(Before.class).value();AspectJExpressionPointcut pointcut = new AspectJExpressionPointcut();pointcut.setExpression(expression);// 通知类AspectJMethodBeforeAdvice advice = new AspectJMethodBeforeAdvice(method, pointcut, factory);// 切面Advisor advisor = new DefaultPointcutAdvisor(pointcut, advice);list.add(advisor);} else if (method.isAnnotationPresent(AfterReturning.class)) {// 解析切点String expression = method.getAnnotation(AfterReturning.class).value();AspectJExpressionPointcut pointcut = new AspectJExpressionPointcut();pointcut.setExpression(expression);// 通知类AspectJAfterReturningAdvice advice = new AspectJAfterReturningAdvice(method, pointcut, factory);// 切面Advisor advisor = new DefaultPointcutAdvisor(pointcut, advice);list.add(advisor);} else if (method.isAnnotationPresent(Around.class)) {// 解析切点String expression = method.getAnnotation(Around.class).value();AspectJExpressionPointcut pointcut = new AspectJExpressionPointcut();pointcut.setExpression(expression);// 通知类AspectJAroundAdvice advice = new AspectJAroundAdvice(method, pointcut, factory);// 切面Advisor advisor = new DefaultPointcutAdvisor(pointcut, advice);list.add(advisor);}}for (Advisor advisor : list) {System.out.println(advisor);}/*@Before 前置通知会被转换为下面原始的 AspectJMethodBeforeAdvice 形式, 该对象包含了如下信息a. 通知代码从哪儿来b. 切点是什么c. 通知对象如何创建, 本例共用同一个 Aspect 对象类似的通知还有1. AspectJAroundAdvice (环绕通知)2. AspectJAfterReturningAdvice3. AspectJAfterThrowingAdvice (环绕通知)4. AspectJAfterAdvice (环绕通知)*/// 2. 通知统一转换为环绕通知 MethodInterceptor/*其实无论 ProxyFactory 基于哪种方式创建代理, 最后干活(调用 advice)的是一个 MethodInvocation 对象a. 因为 advisor 有多个, 且一个套一个调用, 因此需要一个调用链对象, 即 MethodInvocationb. MethodInvocation 要知道 advice 有哪些, 还要知道目标, 调用次序如下将 MethodInvocation 放入当前线程|-> before1 ----------------------------------- 从当前线程获取 MethodInvocation|                                             ||   |-> before2 --------------------          | 从当前线程获取 MethodInvocation|   |                              |          ||   |   |-> target ------ 目标   advice2    advice1|   |                              |          ||   |-> after2 ---------------------          ||                                             ||-> after1 ------------------------------------c. 从上图看出, 环绕通知才适合作为 advice, 因此其他 before、afterReturning 都会被转换成环绕通知d. 统一转换为环绕通知, 体现的是设计模式中的适配器模式- 对外是为了方便使用要区分 before、afterReturning- 对内统一都是环绕通知, 统一用 MethodInterceptor 表示此步获取所有执行时需要的 advice (静态)a. 即统一转换为 MethodInterceptor 环绕通知, 这体现在方法名中的 Interceptors 上b. 适配如下- MethodBeforeAdviceAdapter 将 @Before AspectJMethodBeforeAdvice 适配为 MethodBeforeAdviceInterceptor- AfterReturningAdviceAdapter 将 @AfterReturning AspectJAfterReturningAdvice 适配为 AfterReturningAdviceInterceptor*/Target target = new Target();ProxyFactory proxyFactory = new ProxyFactory();proxyFactory.setTarget(target);proxyFactory.addAdvice(ExposeInvocationInterceptor.INSTANCE); // 准备把 MethodInvocation 放入当前线程proxyFactory.addAdvisors(list);System.out.println(">>>>>>>>>>>>>>>>>>>>>>>>>>>>>>");List<Object> methodInterceptorList = proxyFactory.getInterceptorsAndDynamicInterceptionAdvice(Target.class.getMethod("foo"), Target.class);for (Object o : methodInterceptorList) {System.out.println(o);}System.out.println(">>>>>>>>>>>>>>>>>>>>>>>>>>>>>>");// 3. 创建并执行调用链 (环绕通知s + 目标)MethodInvocation methodInvocation = new ReflectiveMethodInvocation(null, target, Target.class.getMethod("foo"), new Object[0], Target.class, methodInterceptorList);methodInvocation.proceed();/*学到了什么a. 无参数绑定的通知如何被调用b. MethodInvocation 编程技巧: 拦截器、过滤器等等实现都与此类似c. 适配器模式在 Spring 中的体现*/}
}

2_模拟 MethodInvocation

注意点：

proceed() 方法调用链中下一个环绕通知
每个环绕通知内部继续调用 proceed()
调用到没有更多通知了, 就调用目标方法

MethodInvocation 的编程技巧在实现拦截器、过滤器时能用上

package org.springframework.aop.framework;import org.aopalliance.intercept.MethodInterceptor;
import org.aopalliance.intercept.MethodInvocation;import java.lang.reflect.AccessibleObject;
import java.lang.reflect.Method;
import java.util.ArrayList;
import java.util.List;/*模拟调用链过程, 是一个简单的递归过程1. proceed() 方法调用链中下一个环绕通知2. 每个环绕通知内部继续调用 proceed()3. 调用到没有更多通知了, 就调用目标方法*/
public class A18_1 {static class Target {public void foo() {System.out.println("Target.foo()");}}static class Advice1 implements MethodInterceptor {public Object invoke(MethodInvocation invocation) throws Throwable {System.out.println("Advice1.before()");Object result = invocation.proceed();// 调用下一个通知或目标System.out.println("Advice1.after()");return result;}}static class Advice2 implements MethodInterceptor {public Object invoke(MethodInvocation invocation) throws Throwable {System.out.println("Advice2.before()");Object result = invocation.proceed();// 调用下一个通知或目标System.out.println("Advice2.after()");return result;}}static class MyInvocation implements MethodInvocation {private Object target;  // 1private Method method;private Object[] args;List<MethodInterceptor> methodInterceptorList; // 2private int count = 1; // 调用次数public MyInvocation(Object target, Method method, Object[] args, List<MethodInterceptor> methodInterceptorList) {this.target = target;this.method = method;this.args = args;this.methodInterceptorList = methodInterceptorList;}@Overridepublic Method getMethod() {return method;}@Overridepublic Object[] getArguments() {return args;}@Overridepublic Object proceed() throws Throwable { // 调用每一个环绕通知, 调用目标if (count > methodInterceptorList.size()) {// 调用目标， 返回并结束递归return method.invoke(target, args);}// 逐一调用通知, count + 1MethodInterceptor methodInterceptor = methodInterceptorList.get(count++ - 1);return methodInterceptor.invoke(this);}@Overridepublic Object getThis() {return target;}@Overridepublic AccessibleObject getStaticPart() {return method;}}public static void main(String[] args) throws Throwable {Target target = new Target();List<MethodInterceptor> list = new ArrayList<>();list.add(new Advice1());list.add(new Advice2());MyInvocation invocation = new MyInvocation(target, Target.class.getMethod("foo"), new Object[0], list);invocation.proceed();}
}

5_动态通知调用

注意点：

通过 proxyFactory 的 getInterceptorsAndDynamicInterceptionAdvice() 将其他通知统一转换为 MethodInterceptor 环绕通知
所谓动态通知，体现在上面方法的 DynamicInterceptionAdvice 部分，这些通知调用时因为要为通知方法绑定参数，还需再次利用切点表达式
动态通知调用复杂程度高，性能较低

package org.springframework.aop.framework.autoproxy;import org.aspectj.lang.annotation.Aspect;
import org.aspectj.lang.annotation.Before;
import org.springframework.aop.Advisor;
import org.springframework.aop.aspectj.annotation.AnnotationAwareAspectJAutoProxyCreator;
import org.springframework.aop.framework.ProxyFactory;
import org.springframework.aop.framework.ReflectiveMethodInvocation;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.context.annotation.ConfigurationClassPostProcessor;
import org.springframework.context.support.GenericApplicationContext;import java.lang.reflect.Field;
import java.util.List;public class A19 {@Aspectstatic class MyAspect {@Before("execution(* foo(..))") // 静态通知调用，不带参数绑定，执行时不需要切点public void before1() {System.out.println("before1");}@Before("execution(* foo(..)) && args(x)") // 动态通知调用，需要参数绑定，执行时还需要切点对象public void before2(int x) {System.out.printf("before2(%d)%n", x);}}static class Target {public void foo(int x) {System.out.printf("target foo(%d)%n", x);}}@Configurationstatic class MyConfig {@BeanAnnotationAwareAspectJAutoProxyCreator proxyCreator() {return new AnnotationAwareAspectJAutoProxyCreator();}@Beanpublic MyAspect myAspect() {return new MyAspect();}}public static void main(String[] args) throws Throwable {GenericApplicationContext context = new GenericApplicationContext();context.registerBean(ConfigurationClassPostProcessor.class);context.registerBean(MyConfig.class);context.refresh();AnnotationAwareAspectJAutoProxyCreator creator = context.getBean(AnnotationAwareAspectJAutoProxyCreator.class);List<Advisor> list = creator.findEligibleAdvisors(Target.class, "target");Target target = new Target();ProxyFactory factory = new ProxyFactory();factory.setTarget(target);factory.addAdvisors(list);Object proxy = factory.getProxy(); // 获取代理List<Object> interceptorList = factory.getInterceptorsAndDynamicInterceptionAdvice(Target.class.getMethod("foo", int.class), Target.class);for (Object o : interceptorList) {showDetail(o);}System.out.println(">>>>>>>>>>>>>>>>>>>>>>>>>>");ReflectiveMethodInvocation invocation = new ReflectiveMethodInvocation(proxy, target, Target.class.getMethod("foo", int.class), new Object[]{100}, Target.class, interceptorList) {};invocation.proceed();/*学到了什么a. 有参数绑定的通知调用时还需要切点，对参数进行匹配及绑定b. 复杂程度高, 性能比无参数绑定的通知调用低*/}public static void showDetail(Object o) {try {Class<?> clazz = Class.forName("org.springframework.aop.framework.InterceptorAndDynamicMethodMatcher");if (clazz.isInstance(o)) {Field methodMatcher = clazz.getDeclaredField("methodMatcher");methodMatcher.setAccessible(true);Field methodInterceptor = clazz.getDeclaredField("interceptor");methodInterceptor.setAccessible(true);System.out.println("环绕通知和切点：" + o);System.out.println("\t切点为：" + methodMatcher.get(o));System.out.println("\t通知为：" + methodInterceptor.get(o));} else {System.out.println("普通环绕通知：" + o);}} catch (Exception e) {e.printStackTrace();}}
}

补充—— Advice 常见子接口：

增强类型	常见 Advice 子接口/子类	描述
前置通知	`MethodBeforeAdvice`	方法调用前执行
后置通知	`AfterReturningAdvice`	方法调用后且正常返回时执行
环绕通知	`MethodInterceptor`	方法调用前后都可增强，控制流程
异常通知	`ThrowsAdvice`	方法抛出异常时增强
引介通知	`DelegatingIntroductionInterceptor`	为目标对象动态添加接口实现