框架源码系列十：Spring AOP（AOP的核心概念回顾、Spring中AOP的用法、Spring AOP 源码学习）

  • Z时代
  • 2024-01-10
  • 分类：综合

本文内容纲要：

- 一、AOP的核心概念回顾
- 二、Spring中AOP的用法
- 1. 传统Advisor方式
- 2. Aspect语法方式
- Aspect的advice是基于方法的。
- 3. AspectJ注解方式
- 三、Spring AOP 源码学习
- 1、spring aop的工作流程是怎样？以传统的Advisor配置为例进行思考
- 2. 源码阅读思路
- 1、先看配置解析，看标签解析过程都做了什么、完成了什么。
- 2、 看织入的过程
- 3 、看方法被调用时的增强过程
- 4、源码对应的类图

一、AOP的核心概念回顾

https://docs.spring.io/spring/docs/5.1.3.RELEASE/spring-framework-reference/core.html#aop

我们先来看一下下面的这张图

Image

说明：

程序运行时会调用很多方法，调用的很多方法就叫做Join points（连接点，可以被选择来进行增强的方法点），在方法的前或者后选择一个地方来切入，切入的的地方就叫做Pointcut（切入点，选择增强的方法），然后把要增强的功能（Advice）加入到切入点所在的位置。Advice和Pointcut组成一个切面（Aspect）

AOP的几个概念：

Image

Advice、Pointcut、Weaving的特点：

Advice（功能增强）：

1）用户性：由用户提供增强功能的逻辑代码

2）变化的：不同的增强需求，会有不同的逻辑

3）可选时机：可选择在方法前、后、异常时进行功能增强

4）多重的：同一个切入点上可以有多重增强

Pointcut（切入点）：

1）用户性：由用户来指定

2）变化的：用户可灵活指定

3）多点性：用户可以选择在多个点上进行功能增强

Weaving（织入）：

1）无侵入性，因为不改变原类的代码

2）我们在框架中实现

二、Spring中AOP的用法

1. 传统Advisor方式

掌握用法：

1）编程提供Advice，实现对应的Advice接口

2）配置Advisor（advice+pointcut）

Advice接口：

Image

示例代码：

被增强的目标对象：

BeanQ

package com.study.leesmall.spring.sample.aop;
//被增强的目标对象
public class BeanQ {
    public void do1(String task, int time) {
        System.out.println("-------------do1 do " + task + " time:" + time);
    }
    public String service1(String name) {
        System.out.println("-------------servce1 do " + name);
        return name;
    }
    public String service2(String name) {
        System.out.println("-------------servce2 do " + name);
        if (!"s1".equals(name)) {
            throw new IllegalArgumentException("参数 name ！= s1, name=" + name);
        }
        return name + " hello!";
    }
}

编程提供Advice，实现对应的Advice接口:

前置增强:

MyBeforeAdvice

package com.study.leesmall.spring.sample.aop;
import java.lang.reflect.Method;
import org.springframework.aop.MethodBeforeAdvice;
//前置增强
public class MyBeforeAdvice implements MethodBeforeAdvice {
    @Override
    public void before(Method method, Object[] args, Object target) throws Throwable {
        System.out.println("------ MyBeforeAdvice before 增强 " + target + " " + method);
    }
}

环绕增强:

MyArroundAdvice

package com.study.leesmall.spring.sample.aop;
import org.aopalliance.intercept.MethodInterceptor;
import org.aopalliance.intercept.MethodInvocation;
//环绕增强
public class MyArroundAdvice implements MethodInterceptor {
    @Override
    public Object invoke(MethodInvocation invocation) throws Throwable {
        System.out.println("--------- 环绕 -前增强");
        Object ret = invocation.proceed();
        System.out.println("--------- 环绕 -后增强");
        return ret;
    }
}

在/spring-source-study/src/main/java/com/study/leesmall/spring/sample/aop/application.xml里面配置Advisor（advice+pointcut）:

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xmlns:context="http://www.springframework.org/schema/context"
    xmlns:aop="http://www.springframework.org/schema/aop"
    xsi:schemaLocation="http://www.springframework.org/schema/beans
        http://www.springframework.org/schema/beans/spring-beans.xsd
        http://www.springframework.org/schema/context
        http://www.springframework.org/schema/context/spring-context.xsd
        http://www.springframework.org/schema/aop
        http://www.springframework.org/schema/aop/spring-aop.xsd">
    <!-- 传统方式的aop begin -->
    <!--被增强的目标对象  -->
    <bean id="BeanQ" class="com.study.leesmall.spring.sample.aop.BeanQ" />
    <!--配置advice  -->
    <bean id="myBeforeAdvice" class="com.study.leesmall.spring.sample.aop.MyBeforeAdvice" />
    <bean id="yyArroundAdvice" class="com.study.leesmall.spring.sample.aop.MyArroundAdvice" />
    <!--配置pointcut  -->
    <aop:config >
        <!--全局切入点，任何一个aop-config都可以使用  -->
        <aop:pointcut id="doMethods" expression="execution(* com.study.leesmall.spring.sample.aop.*.do*(..))" />
        <aop:advisor advice-ref="myBeforeAdvice" pointcut-ref="doMethods" />
        <aop:advisor advice-ref="yyArroundAdvice"
            pointcut="execution(* com.study.leesmall.spring.sample.aop.*.service*(..))"/>
    </aop:config>
    <!-- 传统方式的aop end -->
</beans>

配置文件里面的注意点：

aop:config 的属性了解

Image

proxy-target-class="false"使用jdk的动态代理 默认配置
proxy-target-class="true"使用cglib的动态代理

Image

Image

掌握 spring Aop 的 API：

Advice：

Image

Advisor的代码：

* Copyright 2002-2017 the original author or authors.
package org.springframework.aop;
import org.aopalliance.aop.Advice;
/**
 * Base interface holding AOP <b>advice</b> (action to take at a joinpoint)
 * and a filter determining the applicability of the advice (such as
 * a pointcut). <i>This interface is not for use by Spring users, but to
 * allow for commonality in support for different types of advice.</i>
 *
 * <p>Spring AOP is based around <b>around advice</b> delivered via method
 * <b>interception</b>, compliant with the AOP Alliance interception API.
 * The Advisor interface allows support for different types of advice,
 * such as <b>before</b> and <b>after</b> advice, which need not be
 * implemented using interception.
 *
 * @author Rod Johnson
 * @author Juergen Hoeller
 */
public interface Advisor {
    /**
     * Common placeholder for an empty {@code Advice} to be returned from
     * {@link #getAdvice()} if no proper advice has been configured (yet).
     * @since 5.0
     */
    Advice EMPTY_ADVICE = new Advice() {};
    /**
     * Return the advice part of this aspect. An advice may be an
     * interceptor, a before advice, a throws advice, etc.
     * @return the advice that should apply if the pointcut matches
     * @see org.aopalliance.intercept.MethodInterceptor
     * @see BeforeAdvice
     * @see ThrowsAdvice
     * @see AfterReturningAdvice
     */
    Advice getAdvice();
    /**
     * Return whether this advice is associated with a particular instance
     * (for example, creating a mixin) or shared with all instances of
     * the advised class obtained from the same Spring bean factory.
     * <p><b>Note that this method is not currently used by the framework.</b>
     * Typical Advisor implementations always return {@code true}.
     * Use singleton/prototype bean definitions or appropriate programmatic
     * proxy creation to ensure that Advisors have the correct lifecycle model.
     * @return whether this advice is associated with a particular target instance
     */
    boolean isPerInstance();
}

Pointcut：

Image

Pointcut的子类：

Image

Advisor的子类：

Image

PointcutAdvisor扩展了Advisor以后就会有一个切面Aspect=Advice+Pointcut

PointcutAdvisor的代码：

* Copyright 2002-2012 the original author or authors.
package org.springframework.aop;
/**
 * Superinterface for all Advisors that are driven by a pointcut.
 * This covers nearly all advisors except introduction advisors,
 * for which method-level matching doesn't apply.
 *
 * @author Rod Johnson
 */
public interface PointcutAdvisor extends Advisor {
    /**
     * Get the Pointcut that drives this advisor.
     */
    Pointcut getPointcut();
}

PointcutAdvisor的子类：

Image

测试类：

AopMain

package com.study.leesmall.spring.sample.aop;
import org.springframework.context.ApplicationContext;
import org.springframework.context.support.GenericXmlApplicationContext;
public class AopMain {
    public static void main(String[] args) {
        ApplicationContext context = new GenericXmlApplicationContext(
                "classpath:com/study/leesmall/spring/sample/aop/application.xml");
        BeanQ bq = context.getBean(BeanQ.class);
        bq.do1("task1", 20);
        System.out.println();
        bq.service1("service1");
        System.out.println();
        bq.service2("ssss");
    }
}

测试结果：

------ MyBeforeAdvice before 增强 com.study.leesmall.spring.sample.aop.BeanQ@1d119efb public void com.study.leesmall.spring.sample.aop.BeanQ.do1(java.lang.String,int)
-------------do1 do task1 time:20
--------- 环绕 -前增强
-------------servce1 do service1
--------- 环绕 -后增强
--------- 环绕 -前增强
-------------servce2 do ssss
Exception in thread "main" java.lang.IllegalArgumentException: 参数 name ！= s1, name=ssss
    at com.study.leesmall.spring.sample.aop.BeanQ.service2(BeanQ.java:18)
    at com.study.leesmall.spring.sample.aop.BeanQ$$FastClassBySpringCGLIB$$3d1515ac.invoke(<generated>)
    at org.springframework.cglib.proxy.MethodProxy.invoke(MethodProxy.java:218)
    at org.springframework.aop.framework.CglibAopProxy$CglibMethodInvocation.invokeJoinpoint(CglibAopProxy.java:749)
    at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:163)
    at com.study.leesmall.spring.sample.aop.MyArroundAdvice.invoke(MyArroundAdvice.java:12)
    at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:186)
    at org.springframework.aop.interceptor.ExposeInvocationInterceptor.invoke(ExposeInvocationInterceptor.java:93)
    at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:186)
    at org.springframework.aop.framework.CglibAopProxy$DynamicAdvisedInterceptor.intercept(CglibAopProxy.java:688)
    at com.study.leesmall.spring.sample.aop.BeanQ$$EnhancerBySpringCGLIB$$2fc5343.service2(<generated>)
    at com.study.leesmall.spring.sample.aop.AopMain.main(AopMain.java:18)

2. Aspect语法方式

Aspect的advice是基于方法的。

掌握用法：

1）定义包含Advice方法的Bean类

2）配置Bean定义

3）配置Aspect（引用包含advice方法的bean），在里面配置各种Advice（method+pointcut）

定义包含Advice方法的Bean类：

AspectAdviceBean：

package com.study.leesmall.spring.sample.aop;
import org.aspectj.lang.JoinPoint;
import org.aspectj.lang.ProceedingJoinPoint;
//定义包含 Advice 方法的 Bean 类
public class AspectAdviceBean {
    public void before1() {
        System.out.println("----------- AspectAdviceBean before1 增强 ");
    }
    //JoinPoint看具体哪个方法被增强了,JoinPoint一定要放在第一个参数
    public void before2(JoinPoint jp) {
        System.out.println("----------- AspectAdviceBean before2 增强 for " + jp);
    }
    //调用被增强的方法时传参数
    //<aop:before method="before3" pointcut="execution(* com.study.leesmall.spring.sample.aop.*.do*(..)) 
    //and args(tk,..)" arg-names=""/>
    //args(tk,..)有两个意思,第一个意思是被增强的方法的第一个参数的类型要和before3的参数tk的类型一样
    //第二个意思是被增强的方法的第一个参数tk要赋值给before3的参数tk
    //arg-names="" 当不能确定方法参数的顺序时可以用这个参数指定arg-names="param1,param2"
    public void before3(String tk) {
        System.out.println("----------- AspectAdviceBean before3  增强  参数tk= " + tk);
    }
    //调用被增强的方法时传参数
    public void before4(String tk, int ti) {
        System.out.println("----------- AspectAdviceBean before4  增强  参数tk= " + tk + " ti=" + ti);
    }
    //ProceedingJoinPoint正在处理的方法
    public Object arround1(ProceedingJoinPoint pjp) throws Throwable {
        System.out.println("----------- AspectAdviceBean arround1 环绕-前增强 for " + pjp);
        Object ret = pjp.proceed();
        System.out.println("----------- AspectAdviceBean arround1 环绕-后增强 for " + pjp);
        return ret;
    }
    public Object arround2(ProceedingJoinPoint pjp, String name) throws Throwable {
        System.out.println("--------- AspectAdviceBean arround2 参数 name=" + name);
        System.out.println("----------- AspectAdviceBean arround2 环绕-前增强 for " + pjp);
        Object ret = pjp.proceed();
        System.out.println("----------- AspectAdviceBean arround2 环绕-后增强 for " + pjp);
        return ret;
    }
    public void afterReturning(Object retValue) {
        System.out.println("----------- AspectAdviceBean afterReturning 增强 , 返回值为： " + retValue);
    }
    public void afterThrowing(JoinPoint jp, Exception e) {
        System.out.println("----------- AspectAdviceBean afterThrowing 增强  for " + jp);
        System.out.println("----------- AspectAdviceBean afterThrowing 增强  异常 ：" + e);
    }
    public void after(JoinPoint jp) {
        System.out.println("----------- AspectAdviceBean after 增强  for " + jp);
    }
}

JoinPoint和ProceedingJoinPoint ：

Image

在/spring-source-study/src/main/java/com/study/leesmall/spring/sample/aop/application.xml里面配置Bean定义

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xmlns:context="http://www.springframework.org/schema/context"
    xmlns:aop="http://www.springframework.org/schema/aop"
    xsi:schemaLocation="http://www.springframework.org/schema/beans
        http://www.springframework.org/schema/beans/spring-beans.xsd
        http://www.springframework.org/schema/context
        http://www.springframework.org/schema/context/spring-context.xsd
        http://www.springframework.org/schema/aop
        http://www.springframework.org/schema/aop/spring-aop.xsd">
    <!-- 传统方式的aop begin -->
    <!--被增强的目标对象  -->
    <bean id="BeanQ" class="com.study.leesmall.spring.sample.aop.BeanQ" />
    <!--配置advice  -->
    <bean id="myBeforeAdvice" class="com.study.leesmall.spring.sample.aop.MyBeforeAdvice" />
    <bean id="yyArroundAdvice" class="com.study.leesmall.spring.sample.aop.MyArroundAdvice" />
    <!--配置pointcut  -->
    <aop:config >
        <aop:pointcut id="doMethods" expression="execution(* com.study.leesmall.spring.sample.aop.*.do*(..))" />
        <aop:advisor advice-ref="myBeforeAdvice" pointcut-ref="doMethods" />
        <aop:advisor advice-ref="yyArroundAdvice"
            pointcut="execution(* com.study.leesmall.spring.sample.aop.*.service*(..))"/>
    </aop:config>
    <!-- 传统方式的aop end -->
    <!-- AspectJ的aop begin -->
    <!-- 配置了包含advice方法的Bean -->
    <bean id="aspectAdviceBean" class="com.study.leesmall.spring.sample.aop.AspectAdviceBean" />
</beans>

3）配置Aspect（引用包含advice方法的bean），在里面配置各种Advice（method+pointcut）

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xmlns:context="http://www.springframework.org/schema/context"
    xmlns:aop="http://www.springframework.org/schema/aop"
    xsi:schemaLocation="http://www.springframework.org/schema/beans
        http://www.springframework.org/schema/beans/spring-beans.xsd
        http://www.springframework.org/schema/context
        http://www.springframework.org/schema/context/spring-context.xsd
        http://www.springframework.org/schema/aop
        http://www.springframework.org/schema/aop/spring-aop.xsd">
    <!-- 传统方式的aop begin -->
    <!--被增强的目标对象  -->
    <bean id="BeanQ" class="com.study.leesmall.spring.sample.aop.BeanQ" />
    <!--配置advice  -->
    <bean id="myBeforeAdvice" class="com.study.leesmall.spring.sample.aop.MyBeforeAdvice" />
    <bean id="yyArroundAdvice" class="com.study.leesmall.spring.sample.aop.MyArroundAdvice" />
    <!--配置pointcut  -->
    <aop:config >
        <aop:pointcut id="doMethods" expression="execution(* com.study.leesmall.spring.sample.aop.*.do*(..))" />
        <aop:advisor advice-ref="myBeforeAdvice" pointcut-ref="doMethods" />
        <aop:advisor advice-ref="yyArroundAdvice"
            pointcut="execution(* com.study.leesmall.spring.sample.aop.*.service*(..))"/>
    </aop:config>
    <!-- 传统方式的aop end -->
    <!-- AspectJ的aop begin -->
    <!-- 配置了包含advice方法的Bean -->
    <bean id="aspectAdviceBean" class="com.study.leesmall.spring.sample.aop.AspectAdviceBean" />
    <!--配置 Aspect （引用包含 advice 方法的 bean），在里面配置各种 Advice（method + pointcut）  -->
    <aop:config>
        <aop:pointcut id="services" expression="execution(* com.study.leesmall.spring.sample.aop.*.service*(..))" />
        <aop:aspect id="a1" ref="aspectAdviceBean" order="1">
            <aop:before method="before1" pointcut-ref="doMethods" />
            <aop:before method="before2" pointcut-ref="doMethods"/>
            <!--args(tk,..)有两个意思,第一个意思是被增强的方法的第一个参数的类型要和before3的参数tk的类型一样
            第二个意思是被增强的方法的第一个参数tk要赋值给before3的参数tk；
            arg-names="" 当不能确定方法参数的顺序时可以用这个参数指定arg-names="param1,param2"
              -->
            <aop:before method="before3" pointcut="execution(* com.study.leesmall.spring.sample.aop.*.do*(..)) and args(tk,..)"/>
            <aop:before method="before4" pointcut="execution(* com.study.leesmall.spring.sample.aop.*.do*(..)) and args(tk,ti)"/>
            <aop:around method="arround1" pointcut-ref="services"/>
            <aop:around method="arround2" pointcut="execution(* com.study.leesmall.spring.sample.aop.*.service*(..)) and args(name)"/>
            <aop:after-returning method="afterReturning" pointcut-ref="services" returning="retValue"/>
            <aop:after-throwing method="afterThrowing" pointcut-ref="services" throwing="e"/>
            <aop:after method="after" pointcut-ref="services"/>
        </aop:aspect>
    </aop:config>
    <!-- AspectJ的aop end -->
</beans>

被增强的目标对象：

package com.study.leesmall.spring.sample.aop;
//被增强的目标对象
public class BeanQ {
    public void do1(String task, int time) {
        System.out.println("-------------do1 do " + task + " time:" + time);
    }
    public String service1(String name) {
        System.out.println("-------------servce1 do " + name);
        return name;
    }
    public String service2(String name) {
        System.out.println("-------------servce2 do " + name);
        /**if (!"s1".equals(name)) {
            throw new IllegalArgumentException("参数 name ！= s1, name=" + name);
        }**/
        return name + " hello!";
    }
}

测试类：

AopMain

package com.study.leesmall.spring.sample.aop;
import org.springframework.context.ApplicationContext;
import org.springframework.context.support.GenericXmlApplicationContext;
public class AopMain {
    public static void main(String[] args) {
        ApplicationContext context = new GenericXmlApplicationContext(
                "classpath:com/study/leesmall/spring/sample/aop/application.xml");
        BeanQ bq = context.getBean(BeanQ.class);
        bq.do1("task1", 20);
        System.out.println();
        bq.service1("service1");
        System.out.println();
        bq.service2("ssss");
    }
}

测试结果：

----------- AspectAdviceBean before1 增强 
----------- AspectAdviceBean before2 增强 for execution(void com.study.mike.spring.sample.aop.BeanQ.do1(leesmall,int))
----------- AspectAdviceBean before3  增强  参数tk= task1
----------- AspectAdviceBean before4  增强  参数tk= task1 ti=20
------ MyBeforeAdvice before 增强 com.study.mike.spring.sample.aop.BeanQ@3a0baae5 public void com.study.mike.spring.sample.aop.BeanQ.do1(java.lang.leesmall,int)
-------------do1 do task1 time:20
----------- AspectAdviceBean arround1 环绕-前增强 for execution(leesmall com.study.mike.spring.sample.aop.BeanQ.service1(leesmall))
--------- AspectAdviceBean arround2 参数 name=service1
----------- AspectAdviceBean arround2 环绕-前增强 for execution(leesmall com.study.mike.spring.sample.aop.BeanQ.service1(leesmall))
--------- 环绕 -前增强
-------------servce1 do service1
--------- 环绕 -后增强
----------- AspectAdviceBean arround2 环绕-后增强 for execution(leesmall com.study.mike.spring.sample.aop.BeanQ.service1(leesmall))
----------- AspectAdviceBean arround1 环绕-后增强 for execution(leesmall com.study.mike.spring.sample.aop.BeanQ.service1(leesmall))
----------- AspectAdviceBean afterReturning 增强 , 返回值为： service1
----------- AspectAdviceBean after 增强  for execution(leesmall com.study.mike.spring.sample.aop.BeanQ.service1(leesmall))
----------- AspectAdviceBean arround1 环绕-前增强 for execution(leesmall com.study.mike.spring.sample.aop.BeanQ.service2(leesmall))
--------- AspectAdviceBean arround2 参数 name=ssss
----------- AspectAdviceBean arround2 环绕-前增强 for execution(leesmall com.study.mike.spring.sample.aop.BeanQ.service2(leesmall))
--------- 环绕 -前增强
-------------servce2 do ssss
--------- 环绕 -后增强
----------- AspectAdviceBean arround2 环绕-后增强 for execution(leesmall com.study.mike.spring.sample.aop.BeanQ.service2(leesmall))
----------- AspectAdviceBean arround1 环绕-后增强 for execution(leesmall com.study.mike.spring.sample.aop.BeanQ.service2(leesmall))
----------- AspectAdviceBean afterReturning 增强 , 返回值为： ssss hello!
----------- AspectAdviceBean after 增强  for execution(leesmall com.study.mike.spring.sample.aop.BeanQ.service2(leesmall))

3. AspectJ注解方式

1）先在pom.xml文件里面引入AspectJ的依赖

<dependency>
            <groupId>org.aspectj</groupId>
            <artifactId>aspectjweaver</artifactId>
            <version>1.9.1</version>
        </dependency>

2）被增强的目标对象

package com.study.leesmall.spring.sample.aop;
//被增强的目标对象
public class BeanQ {
    public void do1(String task, int time) {
        System.out.println("-------------do1 do " + task + " time:" + time);
    }
    public String service1(String name) {
        System.out.println("-------------servce1 do " + name);
        return name;
    }
    public String service2(String name) {
        System.out.println("-------------servce2 do " + name);
        if (!"s1".equals(name)) {
            throw new IllegalArgumentException("参数 name ！= s1, name=" + name);
        }
        return name + " hello!";
    }
}

3）AspectJ注解方式实现AOP

AspectAdviceBeanUseAnnotation

package com.study.leesmall.spring.sample.aop;
import org.aspectj.lang.JoinPoint;
import org.aspectj.lang.ProceedingJoinPoint;
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;
//AspectJ注解方式
@Aspect
public class AspectAdviceBeanUseAnnotation {
    // 定义一个全局的Pointcut
    @Pointcut("execution(* com.study.leesmall.spring.sample.aop.*.do*(..))")
    public void doMethods() {
    }
    // 定义一个全局的Pointcut
    @Pointcut("execution(* com.study.leesmall.spring.sample.aop.*.service*(..))")
    public void services() {
    }
    // 定义一个Before Advice
    @Before("doMethods() and args(tk,..)")
    public void before3(String tk) {
        System.out.println("----------- AspectAdviceBeanUseAnnotation before3  增强  参数tk= " + tk);
    }
    //环绕增强
    @Around("services() and args(name,..)")
    public Object around2(ProceedingJoinPoint pjp, String name) throws Throwable {
        System.out.println("--------- AspectAdviceBeanUseAnnotation arround2 参数 name=" + name);
        System.out.println("----------- AspectAdviceBeanUseAnnotation arround2 环绕-前增强 for " + pjp);
        Object ret = pjp.proceed();
        System.out.println("----------- AspectAdviceBeanUseAnnotation arround2 环绕-后增强 for " + pjp);
        return ret;
    }
    @AfterReturning(pointcut = "services()", returning = "retValue")
    public void afterReturning(Object retValue) {
        System.out.println("----------- AspectAdviceBeanUseAnnotation afterReturning 增强 , 返回值为： " + retValue);
    }
    @AfterThrowing(pointcut = "services()", throwing = "e")
    public void afterThrowing(JoinPoint jp, Exception e) {
        System.out.println("----------- AspectAdviceBeanUseAnnotation afterThrowing 增强  for " + jp);
        System.out.println("----------- AspectAdviceBeanUseAnnotation afterThrowing 增强  异常 ：" + e);
    }
    @After("doMethods()")
    public void after(JoinPoint jp) {
        System.out.println("----------- AspectAdviceBeanUseAnnotation after 增强  for " + jp);
    }
}

4）在/spring-source-study/src/main/java/com/study/leesmall/spring/sample/aop/application2.xml里面配置bean和开启AspectJ注解的支持

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xmlns:context="http://www.springframework.org/schema/context"
    xmlns:aop="http://www.springframework.org/schema/aop"
    xsi:schemaLocation="http://www.springframework.org/schema/beans
        http://www.springframework.org/schema/beans/spring-beans.xsd
        http://www.springframework.org/schema/context
        http://www.springframework.org/schema/context/spring-context.xsd
        http://www.springframework.org/schema/aop
        http://www.springframework.org/schema/aop/spring-aop.xsd">
    <!--被增强的目标对象  -->
    <bean id="BeanQ" class="com.study.leesmall.spring.sample.aop.BeanQ" />
    <!--AspectJ注解方式实现的AOP  -->
    <bean id="aspectAdviceBeanUseAnnotation" class="com.study.leesmall.spring.sample.aop.AspectAdviceBeanUseAnnotation" />
    <!--开启AspectJ注解的支持  -->
    <aop:aspectj-autoproxy></aop:aspectj-autoproxy>
</beans>

开启@Aspectj注解方式支持：

Xml中aop:aspectj-autoproxy</aop:aspectj-autoproxy>注意了解它的属性、及子元素

注解方式开启：

@Configuration
@EnableAspectJAutoProxy
public class AppConfig {
}

5）测试类

package com.study.leesmall.spring.sample.aop;
import org.springframework.context.ApplicationContext;
import org.springframework.context.support.GenericXmlApplicationContext;
public class AopMainUseAspectAnnotation {
    public static void main(String[] args) {
        ApplicationContext context = new GenericXmlApplicationContext(
                "classpath:com/study/leesmall/spring/sample/aop/application2.xml");
        BeanQ bq = context.getBean(BeanQ.class);
        bq.do1("task1", 20);
        System.out.println();
        bq.service1("service1");
    }
}

7）测试结果

----------- AspectAdviceBeanUseAnnotation before3  增强  参数tk= task1
-------------do1 do task1 time:20
----------- AspectAdviceBeanUseAnnotation after 增强  for execution(void com.study.leesmall.spring.sample.aop.BeanQ.do1(String,int))
--------- AspectAdviceBeanUseAnnotation arround2 参数 name=service1
----------- AspectAdviceBeanUseAnnotation arround2 环绕-前增强 for execution(String com.study.leesmall.spring.sample.aop.BeanQ.service1(String))
-------------servce1 do service1
----------- AspectAdviceBeanUseAnnotation arround2 环绕-后增强 for execution(String com.study.leesmall.spring.sample.aop.BeanQ.service1(String))
----------- AspectAdviceBeanUseAnnotation afterReturning 增强 , 返回值为： service1

三、Spring AOP 源码学习

1、spring aop的工作流程是怎样？以传统的Advisor配置为例进行思考

Image

2. 源码阅读思路

1、先看配置解析，看标签解析过程都做了什么、完成了什么。

入口：

E:\repository\org\springframework\spring-aop\5.1.3.RELEASE\spring-aop-5.1.3.RELEASE.jar/META-INF/spring.handlers

http\://www.springframework.org/schema/aop=org.springframework.aop.config.AopNamespaceHandler

org.springframework.aop.config.AopNamespaceHandler：

Image

a）解析aop:config 及它的子元素

org.springframework.aop.config.ConfigBeanDefinitionParser：

Image

Image

1）注册了autoProxyCreator的Bean定义，它是一个ProxyConfig、BeanFactoryAwrare、BeanPostProcessor

下面来看一下配置自动代理的创建者的代码：

org.springframework.aop.config.ConfigBeanDefinitionParser.configureAutoProxyCreator(ParserContext, Element)

->

org.springframework.aop.config.AopNamespaceUtils.registerAspectJAutoProxyCreatorIfNecessary(ParserContext, Element)

->

org.springframework.aop.config.AopConfigUtils.registerAspectJAutoProxyCreatorIfNecessary(BeanDefinitionRegistry, Object)

->

org.springframework.aop.config.AopConfigUtils.registerOrEscalateApcAsRequired(Class<?>, BeanDefinitionRegistry, Object)

Image

Image

所以说自动代理创建者是一个ProxyConfig、BeanFactoryAwrare、BeanPostProcessor

->

org.springframework.aop.config.AopConfigUtils.findPriorityForClass(String)

Image

Image

说明：

org.springframework.aop.framework.autoproxy.InfrastructureAdvisorAutoProxyCreator现在已经不使用了

org.springframework.aop.aspectj.autoproxy.AspectJAwareAdvisorAutoProxyCreator对应于AspectJ的xml方式

<aop:config>
        <aop:pointcut id="services" expression="execution(* com.study.leesmall.spring.sample.aop.*.service*(..))" />
        <aop:aspect id="a1" ref="aspectAdviceBean" order="1">
            <aop:before method="before1" pointcut-ref="doMethods" />
            <aop:before method="before2" pointcut-ref="doMethods"/>
            <!--args(tk,..)有两个意思,第一个意思是被增强的方法的第一个参数的类型要和before3的参数tk的类型一样
            第二个意思是被增强的方法的第一个参数tk要赋值给before3的参数tk；
            arg-names="" 当不能确定方法参数的顺序时可以用这个参数指定arg-names="param1,param2"
              -->
            <aop:before method="before3" pointcut="execution(* com.study.leesmall.spring.sample.aop.*.do*(..)) and args(tk,..)" arg-names=""/>
            <aop:before method="before4" pointcut="execution(* com.study.leesmall.spring.sample.aop.*.do*(..)) and args(tk,ti)"/>
            <aop:around method="arround1" pointcut-ref="services"/>
            <aop:around method="arround2" pointcut="execution(* com.study.leesmall.spring.sample.aop.*.service*(..)) and args(name)"/>
            <aop:after-returning method="afterReturning" pointcut-ref="services" returning="retValue"/>
            <aop:after-throwing method="afterThrowing" pointcut-ref="services" throwing="e"/>
            <aop:after method="after" pointcut-ref="services"/>
        </aop:aspect>
    </aop:config>

查看org.springframework.aop.aspectj.autoproxy.AspectJAwareAdvisorAutoProxyCreator的继承体系：

父类：

Image

子类：

Image

查看org.springframework.aop.framework.autoproxy.AbstractAutoProxyCreator的继承体系，搞清楚它继承实现了什么，他的父类和子类有哪些

父类：

Image

子类：

Image

org.springframework.aop.aspectj.annotation.AnnotationAwareAspectJAutoProxyCreator对应于AspectJ的注解方式：

<bean id="aspectAdviceBeanUseAnnotation" class="com.study.leesamll.spring.sample.aop.AspectAdviceBeanUseAnnotation" />
    <aop:aspectj-autoproxy></aop:aspectj-autoproxy>

<aop:config proxy-target-class="false" expose-proxy="false">对应代码：

org.springframework.aop.config.AopNamespaceUtils.registerAspectJAutoProxyCreatorIfNecessary(ParserContext, Element)

->

org.springframework.aop.config.AopNamespaceUtils.useClassProxyingIfNecessary(BeanDefinitionRegistry, Element)

Image

2）两种配置方式(advisor和aspectJ)解析之后都是向Bean工厂注册了Pointcut和Advisor的Bean定义

b）aop:aspectj-autoproxy开启AspectJ注解支持

1）注册了autoProxyCreator的Bean定义，它是一个ProxyConfig、BeanFactoryAwrare、BeanPostProcessor

org.springframework.aop.config.AopNamespaceHandler.init()

Image

org.springframework.aop.config.AspectJAutoProxyBeanDefinitionParser

org.springframework.aop.config.AspectJAutoProxyBeanDefinitionParser.parse(Element, ParserContext)

org.springframework.aop.config.AopNamespaceUtils.registerAspectJAnnotationAutoProxyCreatorIfNecessary(ParserContext, Element)

Image

<!--开启AspectJ注解的支持  -->
    <aop:aspectj-autoproxy>
        <!-- 满足name里面的表达式(bean名称的表达式)的才进行切面的处理 -->
        <aop:include name="bean名称的表达式"/>
    </aop:aspectj-autoproxy>

Image

<aop:include name="bean名称的表达式"/>对应源码：

Image

c）AspectJ注解的切面在哪里读取加载的？

可能的地方：

BeanDefinitionRegistryPostProcessor x

BeanFactoryPostProcessor x

InstantiationAwareBeanPostProcessor Bean 实例创建前后

BeanPostProcessor

Xml方式的解析：

org.springframework.aop.aspectj.autoproxy.AspectJAwareAdvisorAutoProxyCreator

注解方式的解析：

org.springframework.aop.aspectj.annotation.AnnotationAwareAspectJAutoProxyCreator

两者的关系：

public class AnnotationAwareAspectJAutoProxyCreator extends AspectJAwareAdvisorAutoProxyCreator

org.springframework.aop.aspectj.annotation.AnnotationAwareAspectJAutoProxyCreator.findCandidateAdvisors()

Image

Image

BeanFactoryAspectJAdvisorsBuilder.buildAspectJAdvisors() 中完成了注解的读取、Advisor对象的创建及缓存。

org.springframework.aop.aspectj.annotation.BeanFactoryAspectJAdvisorsBuilder.buildAspectJAdvisors()

Image

org.springframework.aop.aspectj.annotation.ReflectiveAspectJAdvisorFactory.getAdvisors(MetadataAwareAspectInstanceFactory)

Image

2、 看织入的过程

a) 在哪里做的织入？

在org.springframework.aop.aspectj.annotation.AnnotationAwareAspectJAutoProxyCreator.findCandidateAdvisors()里面打个断点拿到调用栈

入口：

com.study.leesmall.spring.sample.aop.AopMainUseAspectAnnotation

Image

b) 如何判断 Bean 要不要被创建代理？如何排除 advice Bean 的？

排除 advice Bean :

跳过advice bean 跳过带有@Aspect注解的自己，不能自己为自己创建代理，否则进入死循环，如AspectAdviceBeanUseAnnotation

org.springframework.aop.aspectj.autoproxy.AspectJAwareAdvisorAutoProxyCreator.shouldSkip(Class<?>, String)

Image

Image

再次进来，是在 PostProcessAfterInitialization()

Image

创建代理的方法：

org.springframework.aop.framework.autoproxy.AbstractAutoProxyCreator.wrapIfNecessary(Object, String, Object)

如何判断 Bean 要不要被创建代理：

Image

c）如何选择 jdk动态代理 还是cglib的动态代理

org.springframework.aop.framework.autoproxy.AbstractAutoProxyCreator.createProxy(Class<?>, String, Object[], TargetSource)

org.springframework.aop.framework.ProxyFactory.getProxy(ClassLoader)

org.springframework.aop.framework.ProxyCreatorSupport.createAopProxy()

org.springframework.aop.framework.DefaultAopProxyFactory.createAopProxy(AdvisedSupport)

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d) 如何来创建代理的，涉及哪些类，如何协作的。

AutoProxyCreator

ProxyConfig ProcxyFactory

AopProxyFactory

AopProxy

3 、看方法被调用时的增强过程

a) 在代理中如何决定对当前方法合格的 advice 的？

　　调用的 Advisor 中 Pointcut 进行匹配

b) 如何组织多个 advice 执行的？

　　责任链模式

org.springframework.aop.framework.JdkDynamicAopProxy.invoke(Object, Method, Object[])

org.springframework.aop.framework.ReflectiveMethodInvocation.proceed()

4、源码对应的类图

Image

本文内容总结：一、AOP的核心概念回顾，二、Spring中AOP的用法，1. 传统Advisor方式，2. Aspect语法方式，Aspect的advice是基于方法的。，3. AspectJ注解方式，三、Spring AOP 源码学习，1、spring aop的工作流程是怎样？以传统的Advisor配置为例进行思考，2. 源码阅读思路，1、先看配置解析，看标签解析过程都做了什么、完成了什么。，2、 看织入的过程，3 、看方法被调用时的增强过程，4、源码对应的类图，

原文链接：https://www.cnblogs.com/leeSmall/p/10236553.html

以上是 框架源码系列十：Spring AOP（AOP的核心概念回顾、Spring中AOP的用法、Spring AOP 源码学习） 的全部内容， 来源链接： utcz.com/z/296657.html

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