spring-framework-core-aop
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AOP概述
AOP中的名词
Spring2.0版本前的AOP
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小试牛刀AOP
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Spring中的通知
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RegexpMethodPointcutAdvisor切入点和通知类关联使用
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给目标类新增接口
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JDK代理和CGLib代理都是动态代理
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一次生成多个代理对象
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根据切入点生成代理对象
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编程方式创建代理对象
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TargetSource
AspectJ风格的SpringAOP
真正的AspectJ编译器
本类调用为什么会失效
AspectJ编译器体验
AOP概述
AOP要做的是将业务代码和功能代码分开实现。例如,一个类中的一个方法要往数据库添加一条数据,删除一条数据。这两个业务操作,都用得上事务管理。那么将事务管理抽取出一个类,类里的方法就是开启事务,提交事务,和回滚事务。AOP负责将事务代码和业务代码无缝结合在一块。
AOP中的名词
通知(Advice):通常我们要对目标类的某个方法进行增强。可以增强的点有方法执行前,后,异常后,finally中,或者前后一块(环绕)。
目标类(Target):业务类。通知就是要和目标类中的方法结合的。
连接点(JoinPoint):一个类的每个方法都可以被增强,这些方法就是连接点。
切入点(Pointcut):切入点匹配器,通常是execution表达式。被匹配到的具体方法,就是切入点。
引入(Introduction):spring允许对一个bean动态的实现一个接口。
代理(Proxy):实现AOP操作的方法就是通过代理,通过创建一个目标类的代理对象,在代理对象里对目标类增强。
切面(Aspect):切入点和通知的类方法结合的过程就是切面。
织入(Weaving):创建代理对象的这个过程就是织入。
Spring2.0前的AOP
1 小试牛刀AOP
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package springcode.aop.spring;/* * @auther 顶风少年 * @mail dfsn19970313@foxmail.com * @date 2020-01-25 18:54 * @notify 通知类 * @version 1.0 */ import org.springframework.aop.MethodBeforeAdvice; import java.lang.reflect.Method; public class BeforeAdvice implements MethodBeforeAdvice { @Override public void before(Method method, Object[] objects, Object o) throws Throwable { System.out.println("我是BeforeAdvice"); } }
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package springcode.aop.spring;/* * @auther 顶风少年 * @mail dfsn19970313@foxmail.com * @date 2020-01-25 21:10 * @notify * @version 1.0 */ public interface TargetInte { void show(); void speak(); void exc(); }
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package springcode.aop.spring;/* * @auther 顶风少年 * @mail dfsn19970313@foxmail.com * @date 2020-01-25 18:56 * @notify 被增强的目标类 * @version 1.0 */ public class Target implements TargetInte { @Override public void show() { System.out.println("我是目标类的show方法"); } @Override public void speak() { System.out.println("我是目标方法的speak方法"); } @Override public void exc() { int i = 1 / 0; } }
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<?xml version="1.0" encoding="UTF-8"?> <beans xmlns="http://www.springframework.org/schema/beans" 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.xsd"> <bean class="springcode.aop.spring.BeforeAdvice" id="beforeAdvice"></bean> <bean id="pointcut1" class="org.springframework.aop.support.JdkRegexpMethodPointcut"> <property name="pattern" value=".*show"></property> </bean> <bean id="advisor" class="org.springframework.aop.support.DefaultPointcutAdvisor"> <property name="pointcut" ref="pointcut1"></property> <property name="advice" ref="beforeAdvice"></property> </bean> <bean class="springcode.aop.spring.Target" id="targetBean"></bean> <bean id="target" class="org.springframework.aop.framework.ProxyFactoryBean"> <property name="target" ref="targetBean"></property> <property name="interceptorNames"> <list> <value>advisor</value> </list> </property> </bean> </beans>
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<?xml version="1.0" encoding="UTF-8"?> <beans xmlns="http://www.springframework.org/schema/beans" 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.xsd"> <bean class="springcode.aop.spring.BeforeAdvice" id="beforeAdvice"></bean> <bean id="pointcut1" class="org.springframework.aop.support.JdkRegexpMethodPointcut"> <property name="pattern" value=".*show"></property> </bean> <bean id="advisor" class="org.springframework.aop.support.DefaultPointcutAdvisor"> <property name="pointcut" ref="pointcut1"></property> <property name="advice" ref="beforeAdvice"></property> </bean> <bean class="springcode.aop.spring.Target" id="targetBean"></bean> <bean id="target" class="org.springframework.aop.framework.ProxyFactoryBean"> <property name="target" ref="targetBean"></property> <property name="proxyInterfaces" value="springcode.aop.spring.TargetInte"/> <property name="interceptorNames"> <list> <value>advisor</value> </list> </property> </bean> </beans>
在上边的代码片段中,先来看BeforeAdvice.class它继承了MethodBeforeAdvice。前边我们提到过连接点的概念,继承了MethodBeforeAdvice则代表该类是一个通知类,并且可以作为前置通知。TargetInte接口,定义的是业务接口它的作用就像是Service接口一样,并没有特殊的意义。Target类实现了业务接口TargetInte。在高版本的Spring中目标类有没有父类并不重要,但是一个目标类,有父接口和没有这是有区别的,我们稍后会提到。对于以上三个类其实对于AOP操作我们必须凑齐的条件已经够了,有目标类,有通知类。最后我们需要在xml配置文件中,将两个类结合使用就行。beforeAdvice将通知类注册成bean,targetBean将目标类注册成bean,JdkRegexpMethodPointcut是Spring提供的一个切入点,通过JDK正则表达式匹配这个切入点可切入的类中的方法。DefaultPointcutAdvisor这个bean当做一个中间层,它将切入点和通知类管理到一起。那么现在我们需要的只剩下对目标类做代理操作了。ProxyFactoryBean它内部必须的参数需要代理的bean(target),需要代理的bean的父接口(proxyInterfaces),最后该代理对象所需要的通知(往下成为拦截器),这是一个列表,意味着我们可以给一个代理对象指定多个通知,它们将依次执行(interceptorNames)
JdkRegexpMethodPointcut切入点匹配了show方法,所以只有show方法有前置通知。
2 Spring中的通知
在spring中定义了4个接口供我们使用。我们可以使用一个Advice类实现4个接口,也可以单独使用。但是一个Advice实现4个接口,意味着该Advice拥有所有的连接点。
1 MethodBeforeAdvice 前置通知
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package springcode.aop.spring;/* * @auther 顶风少年 * @mail dfsn19970313@foxmail.com * @date 2020-01-25 18:54 * @notify 通知类 * @version 1.0 */ import org.springframework.aop.MethodBeforeAdvice; import java.lang.reflect.Method; public class BeforeAdvice implements MethodBeforeAdvice { @Override public void before(Method method, Object[] objects, Object o) throws Throwable { System.out.println("我是BeforeAdvice"); } }
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<?xml version="1.0" encoding="UTF-8"?> <beans xmlns="http://www.springframework.org/schema/beans" 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.xsd"> <bean class="springcode.aop.spring.BeforeAdvice" id="beforeAdvice"></bean> <bean id="pointcut1" class="org.springframework.aop.support.JdkRegexpMethodPointcut"> <property name="pattern" value=".*show"></property> </bean> <bean id="advisor" class="org.springframework.aop.support.DefaultPointcutAdvisor"> <property name="pointcut" ref="pointcut1"></property> <property name="advice" ref="beforeAdvice"></property> </bean> <bean class="springcode.aop.spring.Target" id="targetBean"></bean> <bean id="target" class="org.springframework.aop.framework.ProxyFactoryBean"> <property name="target" ref="targetBean"></property> <property name="proxyInterfaces" value="springcode.aop.spring.TargetInte"/> <property name="interceptorNames"> <list> <value>advisor</value> </list> </property> </bean> </beans>
2 AfterReturningAdvice 后置通知
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package springcode.aop.spring;/* * @auther 顶风少年 * @mail dfsn19970313@foxmail.com * @date 2020-01-25 18:54 * @notify 通知类 * @version 1.0 */ import org.springframework.aop.AfterReturningAdvice; import java.lang.reflect.Method; public class AfterAdvice implements AfterReturningAdvice { @Override public void afterReturning(Object o, Method method, Object[] objects, Object o1) throws Throwable { System.out.println("我是AfterAdvice"); } }
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<?xml version="1.0" encoding="UTF-8"?> <beans xmlns="http://www.springframework.org/schema/beans" 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.xsd"> <bean class="springcode.aop.spring.AfterAdvice" id="afterAdvice"></bean> <bean id="pointcut1" class="org.springframework.aop.support.JdkRegexpMethodPointcut"> <property name="pattern" value=".*show"></property> </bean> <bean id="advisor" class="org.springframework.aop.support.DefaultPointcutAdvisor"> <property name="pointcut" ref="pointcut1"></property> <property name="advice" ref="afterAdvice"></property> </bean> <bean class="springcode.aop.spring.Target" id="targetBean"></bean> <bean id="target" class="org.springframework.aop.framework.ProxyFactoryBean"> <property name="target" ref="targetBean"></property> <property name="proxyInterfaces" value="springcode.aop.spring.TargetInte"/> <property name="interceptorNames"> <list> <value>advisor</value> </list> </property> </bean> </beans>
3 ThrowsAdvice异常通知
这里需要注意了,ThrowsAdvice是一个标记接口,我们不需要覆盖任何方式。但是afterThrowing()方法名是固定的,我们能改变的是参数类型,异常通知会根据业务代码抛出的异常类型,选择合适的异常通知。
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package springcode.aop.spring;/* * @auther 顶风少年 * @mail dfsn19970313@foxmail.com * @date 2020-01-25 22:21 * @notify * @version 1.0 */ import org.springframework.aop.ThrowsAdvice; public class ExceptionAdvice implements ThrowsAdvice { public void afterThrowing(Exception ex){ System.out.println("异常了"); } public void afterThrowing(ArithmeticException ex){ System.out.println("算数异常了"); } }
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<?xml version="1.0" encoding="UTF-8"?> <beans xmlns="http://www.springframework.org/schema/beans" 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.xsd"> <bean class="springcode.aop.spring.ExceptionAdvice" id="exceptionAdvice"></bean> <bean id="pointcut1" class="org.springframework.aop.support.JdkRegexpMethodPointcut"> <property name="patterns"> <list> <value>.*show</value> <value>.*speak</value> <value>.*exc</value> </list> </property> </bean> <bean id="advisor" class="org.springframework.aop.support.DefaultPointcutAdvisor"> <property name="pointcut" ref="pointcut1"></property> <property name="advice" ref="exceptionAdvice"></property> </bean> <bean class="springcode.aop.spring.Target" id="targetBean"></bean> <bean id="target" class="org.springframework.aop.framework.ProxyFactoryBean"> <property name="target" ref="targetBean"></property> <property name="proxyInterfaces" value="springcode.aop.spring.TargetInte"/> <property name="interceptorNames"> <list> <value>advisor</value> </list> </property> </bean> </beans>
4 MethodInterceptor 环绕通知和finally
Spring将环绕通知和finally放到了同一个接口中,invoke(MethodInvocation methodInvocation)参数methodInvocation的proceed()方法,执行目标类的本身的代码。如果出现异常则catch代码块必定执行。看打印结果,show()和speak()方法没有抛出异常,则有前置和后置通知,exc()方法抛出了异常则只有前置和finally通知。
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package springcode.aop.spring;/* * @auther 顶风少年 * @mail dfsn19970313@foxmail.com * @date 2020-01-25 22:35 * @notify * @version 1.0 */ import org.aopalliance.intercept.MethodInterceptor; import org.aopalliance.intercept.MethodInvocation; public class MethodAdvice implements MethodInterceptor { @Override public Object invoke(MethodInvocation methodInvocation) throws Throwable { Object result = null; try { System.out.println("MethodAdvice1"); result = methodInvocation.proceed(); System.out.println("methodAdvice2"); return result; } catch (Exception e) { System.out.println("methodAdvice3"); return result; } } }
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<?xml version="1.0" encoding="UTF-8"?> <beans xmlns="http://www.springframework.org/schema/beans" 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.xsd"> <bean class="springcode.aop.spring.MethodAdvice" id="methodAdvice"></bean> <bean id="pointcut1" class="org.springframework.aop.support.JdkRegexpMethodPointcut"> <property name="patterns"> <list> <value>.*show</value> <value>.*speak</value> <value>.*exc</value> </list> </property> </bean> <bean id="advisor" class="org.springframework.aop.support.DefaultPointcutAdvisor"> <property name="pointcut" ref="pointcut1"></property> <property name="advice" ref="methodAdvice"></property> </bean> <bean class="springcode.aop.spring.Target" id="targetBean"></bean> <bean id="target" class="org.springframework.aop.framework.ProxyFactoryBean"> <property name="target" ref="targetBean"></property> <property name="proxyInterfaces" value="springcode.aop.spring.TargetInte"/> <property name="interceptorNames"> <list> <value>advisor</value> </list> </property> </bean> </beans>
3 RegexpMethodPointcutAdvisor切入点和通知类关联使用
回顾上述内容我们的xml配置文件总是需要做的内容1、将Advice类的注册成bean。2、创建一个JdkRegexpMethodPointcut匹配器,用来确定哪些类的哪些方法可以被代理。3、创建DefaultPointcutAdvisor用来连接Advice和JdkRegexpMethodPointcut。4、将Target目标类注册成bean。5、创建ProxyFactoryBean设置需要代理的bean和拦截器链。似乎是一气呵成,但是总是的第3步骤好像没有起到实际的意义。于是RegexpMethodPointcutAdvisor的出现就是直接在匹配器中注入Advice,然后在ProxyFactoryBean直接引用RegexpMethodPointcutAdvisor。
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<?xml version="1.0" encoding="UTF-8"?> <beans xmlns="http://www.springframework.org/schema/beans" 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.xsd"> <bean class="springcode.aop.spring.MethodAdvice" id="methodAdvice"></bean> <bean id="pointcut1" class="org.springframework.aop.support.RegexpMethodPointcutAdvisor"> <property name="advice"> <ref bean="methodAdvice"/> </property> <property name="patterns"> <list> <value>.*show</value> <value>.*speak</value> <value>.*exc</value> </list> </property> </bean> <bean class="springcode.aop.spring.Target" id="targetBean"></bean> <bean id="target" class="org.springframework.aop.framework.ProxyFactoryBean"> <property name="target" ref="targetBean"></property> <property name="proxyInterfaces" value="springcode.aop.spring.TargetInte"/> <property name="interceptorNames"> <list> <value>pointcut1</value> </list> </property> </bean> </beans>
4 给目标类新增接口
在aop名词中提到了引入的概念,我们可以动态的给代理对象新增一个接口,并且实现它。目标类Target只实现了TargetInte接口,并且有3个方法。现在我们创建一个类并且实现IntroductionInterceptor接口和IOther接口,IOther接口是我们新定义的一个接口给目标类扩展的接口就是它。在IntroductionInterceptor实现类中实现方法implementsInterface()invoke()和IOther接口的doOther(),当方法执行时,所执行的方法属于IOther接口,则调用本类的doOther()。xml配置也做了修改,原来的RegexpMethodPointcutAdvisor换成DefaultIntroductionAdvisor,并且它也不需要方法过滤,DefaultIntroductionAdvisor需要两个参数1、Adivce通知,2、额外增加的接口。看测试结果,Target类本来没有doOther()方法,现在则有了。
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package springcode.aop.spring;/* * @auther 顶风少年 * @mail dfsn19970313@foxmail.com * @date 2020-01-25 18:56 * @notify 被增强的目标类 * @version 1.0 */ public class Target implements TargetInte { @Override public void show() { System.out.println("我是目标类的show方法"); } @Override public void speak() { System.out.println("我是目标方法的speak方法"); } @Override public void exc() { int i = 1 / 0; } }
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package springcode.aop.spring;/* * @auther 顶风少年 * @mail dfsn19970313@foxmail.com * @date 2020-01-25 22:45 * @notify * @version 1.0 */ import org.aopalliance.intercept.MethodInvocation; import org.springframework.aop.IntroductionInterceptor; public class IntroductionInterceptorAdvice implements IntroductionInterceptor, IOther { @Override public void doOther(){ System.out.println("Other对象的功能"); } @Override public Object invoke(MethodInvocation methodInvocation) throws Throwable { if(implementsInterface(methodInvocation.getMethod().getDeclaringClass())){ return methodInvocation.getMethod().invoke(this, methodInvocation.getArguments()); } else{ return methodInvocation.proceed(); } } @Override public boolean implementsInterface(Class arg0){ boolean assignableFrom = arg0.isAssignableFrom(IOther.class); return assignableFrom; } }
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<?xml version="1.0" encoding="UTF-8"?> <beans xmlns="http://www.springframework.org/schema/beans" 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.xsd"> <bean class="springcode.aop.spring.IntroductionInterceptorAdvice" id="introductionInterceptorAdvice"></bean> <bean id="pointcut1" class="org.springframework.aop.support.DefaultIntroductionAdvisor"> <constructor-arg ref="introductionInterceptorAdvice"></constructor-arg> <constructor-arg value="springcode.aop.spring.IOther" /> </bean> <bean class="springcode.aop.spring.Target" id="targetBean"></bean> <bean id="target" class="org.springframework.aop.framework.ProxyFactoryBean"> <property name="target" ref="targetBean"></property> <property name="proxyInterfaces" value="springcode.aop.spring.TargetInte"/> <property name="interceptorNames"> <list> <value>pointcut1</value> </list> </property> </bean> </beans>
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package springcode.aop.spring;/* * @auther 顶风少年 * @mail dfsn19970313@foxmail.com * @date 2020-01-25 23:01 * @notify * @version 1.0 */ public interface IOther { void doOther(); }
5 JDK代理和CGLib代理都是动态代理
在上边我们的Target目标类总是有一个父接口,原因是Spring动态代理有两种实现方式,一种是使用JDK动态代理,JDK代理明确的要想给一个类生成代理对象,这个类必须要有父接口。如果没有父接口的类,则需要通过CGLib动态代理。他们两个都是动态代理也就是在运行时给类生成代理对象,注意是运行时!通俗讲JDK动态代理是通过接口,给目标类创建了一个新的兄弟类。而CGLib代理则是通过目标类创建了一个子类。类Target2并没有父接口,也可以成功生成代理对象。原因是Spring会根据目标类本身有没有父接口,自动的选择使用JDK动态代理还是CGLib动态代理。测试代码System.setProperty(DebuggingClassWriter.DEBUG_LOCATION_PROPERTY, "C:\\class");设置CGLib动态生成的类存放位置。可以看出,对于Target目标类并没有使用CGLib动态代理,只有Target2才使用了。
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package springcode.aop.spring;/* * @auther 顶风少年 * @mail dfsn19970313@foxmail.com * @date 2020-01-26 11:39 * @notify * @version 1.0 */ public class Target2 { public void show() { System.out.println("我是目标类2的show方法"); } }
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<?xml version="1.0" encoding="UTF-8"?> <beans xmlns="http://www.springframework.org/schema/beans" 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.xsd"> <bean class="springcode.aop.spring.BeforeAdvice" id="beforeAdvice"></bean> <bean id="pointcut1" class="org.springframework.aop.support.RegexpMethodPointcutAdvisor"> <property name="advice"> <ref bean="beforeAdvice"/> </property> <property name="patterns"> <list> <value>.*show</value> <value>.*speak</value> <value>.*exc</value> </list> </property> </bean> <bean class="springcode.aop.spring.Target" id="targetBean"></bean> <bean id="target" class="org.springframework.aop.framework.ProxyFactoryBean"> <property name="target" ref="targetBean"></property> <property name="interceptorNames"> <list> <value>pointcut1</value> </list> </property> </bean> <bean class="springcode.aop.spring.Target2" id="targetBean2"></bean> <bean id="target2" class="org.springframework.aop.framework.ProxyFactoryBean"> <property name="target" ref="targetBean2"></property> <property name="interceptorNames"> <list> <value>pointcut1</value> </list> </property> </bean> </beans>
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@Test public void t8() { System.setProperty(DebuggingClassWriter.DEBUG_LOCATION_PROPERTY, "C:\\class"); ClassPathXmlApplicationContext context = new ClassPathXmlApplicationContext("classpath:springresource/cglib.xml"); TargetInte target = (TargetInte) context.getBean("target"); target.show(); Target2 target2 = (Target2) context.getBean("target2"); target2.show(); }
当然对于有父接口的目标类,我们也可以强制的让它使用CGLib代理。ProxyFactoryBean的proxyTargetClass属性设置为true则强制使用CGLib代理。
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<?xml version="1.0" encoding="UTF-8"?> <beans xmlns="http://www.springframework.org/schema/beans" 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.xsd"> <bean class="springcode.aop.spring.BeforeAdvice" id="beforeAdvice"></bean> <bean id="pointcut1" class="org.springframework.aop.support.RegexpMethodPointcutAdvisor"> <property name="advice"> <ref bean="beforeAdvice"/> </property> <property name="patterns"> <list> <value>.*show</value> <value>.*speak</value> <value>.*exc</value> </list> </property> </bean> <bean class="springcode.aop.spring.Target" id="targetBean"></bean> <bean id="target" class="org.springframework.aop.framework.ProxyFactoryBean"> <property name="target" ref="targetBean"></property> <property name="proxyTargetClass" value="true"/> <property name="interceptorNames"> <list> <value>pointcut1</value> </list> </property> </bean> <bean class="springcode.aop.spring.Target2" id="targetBean2"></bean> <bean id="target2" class="org.springframework.aop.framework.ProxyFactoryBean"> <property name="target" ref="targetBean2"></property> <property name="interceptorNames"> <list> <value>pointcut1</value> </list> </property> </bean> </beans>
6 一次生成多个代理对象
有没有发现一个问题,ProxyFactoryBean虽然它可以指定多个拦截器,一次只能给我们生成一个代理对象。BeanNameAutoProxyCreator则完全的消除这个弊端,BeanNameAutoProxyCreator允许我们匹配bean的Name从而确定我们需要几个代理对象。属性beanNames的值设置为target*,则代表所有target开头的bean都会生成代理对象。
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<?xml version="1.0" encoding="UTF-8"?> <beans xmlns="http://www.springframework.org/schema/beans" 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.xsd"> <bean class="springcode.aop.spring.BeforeAdvice" id="beforeAdvice"></bean> <bean id="pointcut1" class="org.springframework.aop.support.RegexpMethodPointcutAdvisor"> <property name="advice"> <ref bean="beforeAdvice"/> </property> <property name="patterns"> <list> <value>.*show</value> </list> </property> </bean> <bean class="springcode.aop.spring.Target" id="target"></bean> <bean class="springcode.aop.spring.Target2" id="target2"></bean> <bean class="org.springframework.aop.framework.autoproxy.BeanNameAutoProxyCreator"> <property name="beanNames" value="targe*"/> <property name="interceptorNames"> <list> <value>pointcut1</value> </list> </property> </bean> </beans>
7 根据切入点生成代理对象
思考一个问题,我们配置的RegexpMethodPointcutAdvisor有了目标类和目标方法的匹配规则,然后使用ProxyFactoryBean或者BeanNameAutoProxyCreator确定给哪个类做代理对象,然后确定使用什么拦截器。如果我们换个思考方式,只要是RegexpMethodPointcutAdvisor匹配的目标类和目标方法我们就想生成代理类。类DefaultAdvisorAutoProxyCreator则会自动的收集RegexpMethodPointcutAdvisor匹配到的类,并生成代理对象。在配置文件中我们配置了两个RegexpMethodPointcutAdvisor,第一个是前置通知对show和speak方法进行匹配,第二个则是后置通知只对show方法进行匹配。DefaultAdvisorAutoProxyCreator我们不设置任何的属性。可以看到结果,show方法有前置和后置通知,而speak方法只有前置通知。不管是Target目标类还是Target2目标类,都生成了代理对象。
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<?xml version="1.0" encoding="UTF-8"?> <beans xmlns="http://www.springframework.org/schema/beans" 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.xsd"> <bean class="springcode.aop.spring.BeforeAdvice" id="beforeAdvice"></bean> <bean id="pointcut1" class="org.springframework.aop.support.RegexpMethodPointcutAdvisor"> <property name="advice"> <ref bean="beforeAdvice"/> </property> <property name="patterns"> <list> <value>.*show</value> <value>.*speak</value> </list> </property> </bean> <bean class="springcode.aop.spring.AfterAdvice" id="afterAdvice"></bean> <bean id="pointcut2" class="org.springframework.aop.support.RegexpMethodPointcutAdvisor"> <property name="advice"> <ref bean="afterAdvice"/> </property> <property name="patterns"> <list> <value>.*show</value> </list> </property> </bean> <bean class="springcode.aop.spring.Target" id="target"></bean> <bean class="springcode.aop.spring.Target2" id="target2"></bean> <bean id="autoProxyCreator" class="org.springframework.aop.framework.autoproxy.DefaultAdvisorAutoProxyCreator"> </bean> </beans>
8 编程方式创建代理对象
同样的SpringAOP允许我们使用java代码的方式创建代理对象。仔细观察你会发现xml配置方式使用的是ProxyFactoryBean类而java代码ProxyFactory类除此之外他们几乎没有任何的差别。重要的在于我们怎样理解SpringAop提供的组件,又怎么把组件连接起来。
9 TargetSource
TargetSource
TargetSource为了使代理对象有更多的原则操作而诞生的,简单说生成代理对象这一个操作,我们可以对他进行装饰。如果我们不设置TargetSource,默认的使用EmptyTargetSource。TargetSource的实现类有很多,这里我们只看文档上提及的几个。
1 HotSwappableTargetSource
作用可动态的切换目标源,注意!!!ProxyFactoryBean必须要是scope="prototype"否则会出问题的。在下面xml代码中,ProxyFactoryBean设置target,而是设置了一个targetSource,而在targetSource中设置了target。获取HotSwappableTargetSource的bean然后调用swap()方法,这里需要传递一个对象,需要替换的对象。
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<?xml version="1.0" encoding="UTF-8"?> <beans xmlns="http://www.springframework.org/schema/beans" 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.xsd"> <bean class="springcode.aop.spring.BeforeAdvice" id="beforeAdvice"></bean> <bean id="pointcut1" class="org.springframework.aop.support.RegexpMethodPointcutAdvisor"> <property name="advice"> <ref bean="beforeAdvice"/> </property> <property name="patterns"> <list> <value>.*show</value> <value>.*speak</value> <value>.*exc</value> </list> </property> </bean> <bean class="springcode.aop.spring.Target2" id="targetBean2"></bean> <bean id="hotSwappableTargetSource" class="org.springframework.aop.target.HotSwappableTargetSource"> <constructor-arg ref="targetBean2"/> </bean> <bean id="target" class="org.springframework.aop.framework.ProxyFactoryBean" scope="prototype"> <property name="targetSource" ref="hotSwappableTargetSource"/> <property name="interceptorNames"> <list> <value>pointcut1</value> </list> </property> </bean> </beans>
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package springcode.aop.spring;/* * @auther 顶风少年 * @mail dfsn19970313@foxmail.com * @date 2020-01-25 18:56 * @notify 被增强的目标类 * @version 1.0 */ public class Target3 { public void show() { System.out.println("我是目标类3的show方法"); } public void speak() { System.out.println("我是目标方法3的speak方法"); } public void exc() { int i = 1 / 0; } }
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package springcode.aop.spring;/* * @auther 顶风少年 * @mail dfsn19970313@foxmail.com * @date 2020-01-26 11:39 * @notify * @version 1.0 */ public class Target2 { public void show() { System.out.println("我是目标类2的show方法"); } }
从源码中看,道理很简单。所以一定要把ProxyFactoryBean设置为原型,如果是单例bean被Spring存放到单例池里,那下次在getBean()还是同一个,这样根本无法切换目标源。
2 PrototypeTargetSource
一般的我们创建的代理对象都是单例的,PrototypeTargetSource帮我们创建不同实例的代理对象。Target目标类需要设置scope="prototype"
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<?xml version="1.0" encoding="UTF-8"?> <beans xmlns="http://www.springframework.org/schema/beans" 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.xsd"> <bean class="springcode.aop.spring.BeforeAdvice" id="beforeAdvice"></bean> <bean id="pointcut1" class="org.springframework.aop.support.RegexpMethodPointcutAdvisor"> <property name="advice"> <ref bean="beforeAdvice"/> </property> <property name="patterns"> <list> <value>.*show</value> <value>.*speak</value> <value>.*exc</value> </list> </property> </bean> <bean class="springcode.aop.spring.Target2" id="targetBean2" scope="prototype"></bean> <!-- <bean id="hotSwappableTargetSource" class="org.springframework.aop.target.HotSwappableTargetSource">--> <!-- <constructor-arg ref="targetBean2"/>--> <!-- </bean>--> <bean id="prototypeTargetSource" class="org.springframework.aop.target.PrototypeTargetSource"> <property name="targetBeanName" value="targetBean2"/> </bean> <bean id="target" class="org.springframework.aop.framework.ProxyFactoryBean"> <property name="targetSource" ref="prototypeTargetSource"/> <property name="interceptorNames"> <list> <value>pointcut1</value> </list> </property> </bean> </beans>
AspectJ风格的SpringAOP
1 Aspect风格和Aspect编译器
Aspect风格的AOP还是SpringAOP使用JDK动态代理或者是CGLib动态代理,只是注解和xml方式和Aspect编译器类似,Aspect编译器是静态代理。动态代理在类运行时创建新的代理类,静态代理在编译时改变类的字节码,不会有新的Class产生。Spring支持使用Aspect编译器,下边会讲到。
2 一个简单的入门
SpringBoot项目导入AOP包,创建一个目标类,这个目标类没有父接口,意味着使用的CGLib动态代理。定义一个Advice类,@Componnet和@Aspect注解不可少。方法pointcut()是一个空方法,方法上使用@Pointcut注解声明目标类和切入点。方法before()上注解@Before值为任意一个被@Pointcut注解的方法。这样就完成了AOP的代理对象的操作,有点简单哦。
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<dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-aop</artifactId> </dependency>
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package springcode.aop.aspectj;/* * @auther 顶风少年 * @mail dfsn19970313@foxmail.com * @date 2020-01-27 14:39 * @notify * @version 1.0 */ import org.springframework.stereotype.Component; import java.io.IOException; @Component public class Person { public void show()throws Exception { System.out.println("开始我的表演"); } }
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package springcode.aop.aspectj;/* * @auther 顶风少年 * @mail dfsn19970313@foxmail.com * @date 2020-01-27 14:27 * @notify * @version 1.0 */ import org.aspectj.lang.annotation.Before; import org.aspectj.lang.annotation.Pointcut; import org.springframework.stereotype.Component; import org.aspectj.lang.annotation.Aspect; @Component @Aspect public class Aspectj1 { //返回类型模式、方法名模式和参数模式 @Pointcut(value = "execution(public * springcode.aop..show(..)throws Exception)") public void pointcut(){} @Before(value = "pointcut()") public void before(){ System.out.println("准备表演"); } }
3 支持的切入点匹配器
@Pointcut注解的value值,Spring最多的支持9中匹配模式。execution、within、this、target、args、@target、@args、@within、@annotation最常用的还是execution
execution:用于匹配方法执行连接点。这是使用Spring AOP时要使用的主要切入点指示器。格式为 方法修饰符 返回值类型 包名类名(参数列表)异常类型。其中返回类型模式、方法名模式和参数模式是不可少的,其他的都可以省略。@Pointcut(value = "execution( * *show(..))") 代表任意方法修饰符,任意返回值类型,任意包下以show结尾方法参数任意,异常类型任意的都匹配。
4 切入点组合
&& || !组合多个切入点匹配器使用 !的表达式不知道怎么用Q_Q
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package springcode.aop.aspectj;/* * @auther 顶风少年 * @mail dfsn19970313@foxmail.com * @date 2020-01-27 14:27 * @notify * @version 1.0 */ import org.aspectj.lang.annotation.Aspect; import org.aspectj.lang.annotation.Before; import org.aspectj.lang.annotation.Pointcut; import org.springframework.stereotype.Component; @Component @Aspect public class Aspectj2 { @Pointcut(value = "execution(* show(..))") public void pointcut(){} @Pointcut(value = "execution(* rrrshow(..))") public void pointcut2(){} @Pointcut(value = "pointcut()&&pointcut2()") public void pointcut3(){} @Pointcut(value = "pointcut()||pointcut2()") public void pointcut4(){} @Before(value = "pointcut4()") public void before(){ System.out.println("准备表演"); } }
5 注解方式的连接点
@Before
前置通知@Before,连接点的value可以给切入点的方法名,也可以直接写匹配器。
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package springcode.aop.aspectj;/* * @auther 顶风少年 * @mail dfsn19970313@foxmail.com * @date 2020-01-27 14:27 * @notify * @version 1.0 */ import org.aspectj.lang.annotation.Aspect; import org.aspectj.lang.annotation.Before; import org.aspectj.lang.annotation.Pointcut; import org.springframework.stereotype.Component; @Component @Aspect public class Aspectj3 { @Before(value = "execution(* show(..))") public void before(){ System.out.println("准备表演"); } }
@After
@After后置通知,无论目标方法是否有异常,该通知都会执行。可以当做finally使用。
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package springcode.aop.aspectj;/* * @auther 顶风少年 * @mail dfsn19970313@foxmail.com * @date 2020-01-27 14:27 * @notify * @version 1.0 */ import org.aspectj.lang.annotation.After; import org.aspectj.lang.annotation.Aspect; import org.springframework.stereotype.Component; @Component @Aspect public class Aspectj6 { @After(value = "execution(* show2(..))") public void before() { System.out.println("after"); } }
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package springcode.aop.aspectj;/* * @auther 顶风少年 * @mail dfsn19970313@foxmail.com * @date 2020-01-27 14:39 * @notify * @version 1.0 */ import org.springframework.stereotype.Component; @Component public class Person2 { public int show()throws Exception { System.out.println("person2.show()"); return 100; } public void show2(){ int i = 1/0; } }
@AfterReturning
后置通知@AfterRetruning可以获取目标对象方法执行后的返回值。需要注意的是returning的值必须和连接点的参数名一样。和@After不同的是,@AfterReturning只能在没有异常时才会执行。
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package springcode.aop.aspectj;/* * @auther 顶风少年 * @mail dfsn19970313@foxmail.com * @date 2020-01-27 14:39 * @notify * @version 1.0 */ import org.springframework.stereotype.Component; @Component public class Person2 { public int show()throws Exception { System.out.println("person2.show()"); return 100; } }
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package springcode.aop.aspectj;/* * @auther 顶风少年 * @mail dfsn19970313@foxmail.com * @date 2020-01-27 14:27 * @notify * @version 1.0 */ import org.aspectj.lang.annotation.AfterReturning; import org.aspectj.lang.annotation.Aspect; import org.aspectj.lang.annotation.Before; import org.springframework.stereotype.Component; @Component @Aspect public class Aspectj4 { @AfterReturning(value = "execution(* show(..))", returning = "r") public void before(Object r) { System.out.println("after--返回值是:"+r); } }
@AfterThrowing
@AfterThrowing发生在异常后,如果要指定异常类型,则可以在参数中声明要拦截的异常,抛出的异常是拦截异常或其子类则可以拦截。
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package springcode.aop.aspectj;/* * @auther 顶风少年 * @mail dfsn19970313@foxmail.com * @date 2020-01-27 14:27 * @notify * @version 1.0 */ import org.aspectj.lang.annotation.AfterReturning; import org.aspectj.lang.annotation.AfterThrowing; import org.aspectj.lang.annotation.Aspect; import org.springframework.stereotype.Component; import java.io.IOException; @Component @Aspect public class Aspectj5 { @AfterThrowing(value = "execution(* show2(..))",throwing = "e") public void before(Exception e) { System.out.println("throwing"); } }
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package springcode.aop.aspectj;/* * @auther 顶风少年 * @mail dfsn19970313@foxmail.com * @date 2020-01-27 14:39 * @notify * @version 1.0 */ import org.springframework.stereotype.Component; @Component public class Person2 { public int show()throws Exception { System.out.println("person2.show()"); return 100; } public void show2(){ int i = 1/0; } }
@Around
在目标类目标方法的开始和结束处增强,当然也可以使用catch将异常捕获,当做finally使用。
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package springcode.aop.aspectj;/* * @auther 顶风少年 * @mail dfsn19970313@foxmail.com * @date 2020-01-27 14:27 * @notify * @version 1.0 */ import org.aspectj.lang.ProceedingJoinPoint; import org.aspectj.lang.annotation.Around; import org.aspectj.lang.annotation.Aspect; import org.springframework.stereotype.Component; @Component @Aspect public class Aspectj7 { @Around(value = "execution(* show*(..))") public Object around(ProceedingJoinPoint pjp) { Object proceed = null; try { System.out.println("around1"); proceed = pjp.proceed(); System.out.println("around2"); return proceed; } catch (Throwable e) { System.out.println("异常了"); return proceed; } } }
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package springcode.aop.aspectj;/* * @auther 顶风少年 * @mail dfsn19970313@foxmail.com * @date 2020-01-27 14:39 * @notify * @version 1.0 */ import org.springframework.stereotype.Component; @Component public class Person2 { public int show()throws Exception { System.out.println("person2.show()"); return 100; } public void show2(){ int i = 1/0; } }
6 连接点的通用参数
所有的注解连接点都可以带一个参数,JoinPoint,除了@Around注解除外,其他的都需要将该参数放到参数列表的第一个位置。通过该参数,可以获取到目标对象,和代理对象的信息。
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package springcode.aop.aspectj;/* * @auther 顶风少年 * @mail dfsn19970313@foxmail.com * @date 2020-01-27 21:05 * @notify * @version 1.0 */ import org.springframework.stereotype.Component; @Component public class Person3 { public void add(Integer arg1, Integer arg2) { System.out.println(arg1 + arg2); } }
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package springcode.aop.aspectj;/* * @auther 顶风少年 * @mail dfsn19970313@foxmail.com * @date 2020-01-27 21:03 * @notify * @version 1.0 */ import org.aspectj.lang.JoinPoint; import org.aspectj.lang.annotation.Around; import org.aspectj.lang.annotation.Aspect; import org.aspectj.lang.annotation.Before; import org.springframework.stereotype.Component; @Component @Aspect public class Aspectj8 { @Before(value = "execution(* add(..))") public void before(JoinPoint joinPoint){ //获取原对象的参数 Object[] args = joinPoint.getArgs(); for (Object o:args){ System.out.println(o); } //获取原对象 Object target = joinPoint.getTarget(); System.out.println(target); System.out.println("before"); } }
7 XML方式使用AOP
xml配置方式aop配置都在<aop:config>标签内<aop:pointcut expression="execution(* *(..))" id="anyMethod"/> 声明切入点匹配器。<aop:aspect>引用一个Advice的bean在内部可配置连接点。连接点既可以直接使用pointcut匹配器的id,也可以自己配置pointcut。同样的,Advice方法都可以添加JoinPoint作为参数。
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package springcode.aop.xmlaspectj;/* * @auther 顶风少年 * @mail dfsn19970313@foxmail.com * @date 2020-01-27 22:01 * @notify * @version 1.0 */ public class User { public String name = "张三"; public void add() { System.out.println("添加用户"); } public void update() { System.out.println("修改用户"); } public void delete() { System.out.println("删除用户"); } public User getUser() { return this; } }
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package springcode.aop.xmlaspectj;/* * @auther 顶风少年 * @mail dfsn19970313@foxmail.com * @date 2020-01-27 22:03 * @notify * @version 1.0 */ import org.aspectj.lang.JoinPoint; import org.aspectj.lang.ProceedingJoinPoint; public class UserAdvice { public void before(JoinPoint joinPoint) { User target = (User)joinPoint.getTarget(); System.out.println(target.name); System.out.println("before"); } public void after() { System.out.println("after"); } public void afterReturn(User user) { System.out.println(user.name); System.out.println("afterReturn"); } public void thro() { System.out.println("throws"); } public Object around(ProceedingJoinPoint proceedingJoinPoint) { Object object = null; try { System.out.println("around1"); object = proceedingJoinPoint.proceed(); System.out.println("around2"); return object; } catch (Throwable e) { System.out.println("around3"); return object; } } }
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<?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: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/aop http://www.springframework.org/schema/aop/spring-aop.xsd"> <!-- 配置切面类 bean --> <bean id="advice" class="springcode.aop.xmlaspectj.UserAdvice"></bean> <!-- 配置目标类 bean --> <bean id="user" class="springcode.aop.xmlaspectj.User"></bean> <!-- aop 配置 --> <aop:config> <!-- 自定义切入点 --> <aop:pointcut expression="execution(* *(..))" id="anyMethod"/> <aop:aspect ref="advice"> <!-- 前置通知 --> <aop:before method="before" pointcut-ref="anyMethod"/> <!-- 最终通知 --> <aop:after method="after" pointcut-ref="anyMethod"/> <!-- 后置通知 --> <aop:after-returning method="afterReturn" pointcut="execution(* getUser(..))" returning="user"/> <!-- 环绕通知 --> <aop:around method="around" pointcut-ref="anyMethod"/> <!-- 异常抛出通知 --> <aop:after-throwing method="thro" pointcut-ref="anyMethod"/> </aop:aspect> </aop:config> </beans>
8 给目标对象增加接口
注解方式使用注解@DeclareParents被注解的必须是一个接口,value指定代理对象类型匹配器,defaultImpl必须是接口的子类。xml配置方式类似。
注解方式
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package springcode.aop.addInte;/* * @auther 顶风少年 * @mail dfsn19970313@foxmail.com * @date 2020-01-27 22:49 * @notify * @version 1.0 */ import org.springframework.stereotype.Component; @Component public class Phone { public void call(){ System.out.println("喂喂喂打电话"); } }
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package springcode.aop.addInte;/* * @auther 顶风少年 * @mail dfsn19970313@foxmail.com * @date 2020-01-27 22:50 * @notify * @version 1.0 */ import org.springframework.stereotype.Component; public interface Computer { public void play(); }
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package springcode.aop.addInte;/* * @auther 顶风少年 * @mail dfsn19970313@foxmail.com * @date 2020-01-27 22:50 * @notify * @version 1.0 */ import org.springframework.stereotype.Component; public class DEComputer implements Computer{ public void play(){ System.out.println("啪啪啪,我在写代码。。"); } }
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package springcode.aop.addInte;/* * @auther 顶风少年 * @mail dfsn19970313@foxmail.com * @date 2020-01-27 22:51 * @notify * @version 1.0 */ import org.aspectj.lang.annotation.Aspect; import org.aspectj.lang.annotation.DeclareParents; import org.springframework.stereotype.Component; @Component @Aspect public class AdviceInte { @DeclareParents(value = "springcode.aop.addInte.Phone", defaultImpl = DEComputer.class) public Computer computer; }
XML配置方式
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<?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: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/aop http://www.springframework.org/schema/aop/spring-aop.xsd"> <aop:config> <aop:aspect > <aop:declare-parents types-matching="springcode.aop.addInte.Phone" implement-interface="springcode.aop.addInte.Computer" default-impl="springcode.aop.addInte.DEComputer" /> </aop:aspect> </aop:config> <!-- 目标类 --> <bean id="phone" class="springcode.aop.addInte.Phone"></bean> </beans>
真正的AspectJ编译器
本类调用为什么会失效
类DB封装了一个List集合,DBTransaction是一个普通的注解类。通知类DBTransactionAspect中声明连接点匹配规则是@Pointcut("@annotation(springcode.aop.transactiontest.DBTransaction)")这意味着,任何使用@DBTransaction的方法都将会被拦截。around()是一个环绕通知,当被拦截的方法内部抛出异常,则删掉List中最后一条数据。Service类中的add方法,是业务类,它模拟向数据库中添加数据,当参数是true是则会抛出异常。
结果是我们想要看到的,这其实就是模拟一个事务。
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package springcode.aop.transactiontest; import java.lang.annotation.*; @Target(ElementType.METHOD) @Retention(RetentionPolicy.RUNTIME) @Documented public @interface DBTransaction { }
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package springcode.aop.transactiontest;/* * @auther 顶风少年 * @mail dfsn19970313@foxmail.com * @date 2020-01-28 14:53 * @notify * @version 1.0 */ import org.springframework.stereotype.Component; import java.util.ArrayList; @Component public class DB { public ArrayList<String> mysql = new ArrayList<>(); }
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package springcode.aop.transactiontest;/* * @auther 顶风少年 * @mail dfsn19970313@foxmail.com * @date 2020-01-28 15:26 * @notify * @version 1.0 */ import org.aspectj.lang.ProceedingJoinPoint; import org.aspectj.lang.annotation.Around; import org.aspectj.lang.annotation.Aspect; import org.aspectj.lang.annotation.Pointcut; import org.springframework.beans.factory.annotation.Autowired; import org.springframework.stereotype.Component; @Component @Aspect public class DBTransactionAspect { @Autowired private DB db; @Pointcut("@annotation(springcode.aop.transactiontest.DBTransaction)") public void Pointcut() { } @Around("Pointcut()") public void around(ProceedingJoinPoint pjp) { Object[] args = pjp.getArgs(); for (Object s : args) { String o = (String) s; System.out.println("目标对象方法的参数--"+o); } Object object = null; try { System.out.println("事务开始"); object = pjp.proceed(); System.out.println("事务提交"); } catch (Throwable throwable) { db.mysql.remove(db.mysql.size() - 1); System.out.println("事务回滚"); } } }
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package springcode.aop.transactiontest;/* * @auther 顶风少年 * @mail dfsn19970313@foxmail.com * @date 2020-01-28 14:56 * @notify * @version 1.0 */ import org.springframework.beans.factory.annotation.Autowired; import org.springframework.stereotype.Component; @Component public class Service { @Autowired private DB db; @DBTransaction public void add(String flag, String s) { System.out.println("啊我是一个平凡的service,但是我的使命就是要添加一个字符串到db中"); db.mysql.add("哈哈哈哈"); if (flag.equals("true")) { int i = 1 / 0; } } }
现在业务变动了,在Service中新增了一个方法client()所有的客户端只能通过它访问add()方法。此时我们发现,无论抛不抛异常add()方法都没有被拦截。这个问题很关键,所以我首先贴出来官方的解释,然后在拼凑自己的理解。
The key thing to understand here is that the client code inside the main(..)
method of the Main
class has a reference to the proxy. This means that method calls on that object reference are calls on the proxy. As a result, the proxy can delegate to all of the interceptors (advice) that are relevant to that particular method call. However, once the call has finally reached the target object (the SimplePojo
, reference in this case), any method calls that it may make on itself, such as this.bar()
or this.foo()
, are going to be invoked against the this
reference, and not the proxy. This has important implications. It means that self-invocation is not going to result in the advice associated with a method invocation getting a chance to execute.
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package springcode.aop.transactiontest;/* * @auther 顶风少年 * @mail dfsn19970313@foxmail.com * @date 2020-01-28 14:56 * @notify * @version 1.0 */ import org.springframework.beans.factory.annotation.Autowired; import org.springframework.stereotype.Component; @Component public class Service { @Autowired private DB db; public void client(String flag, String s) { add(flag, "add"); } @DBTransaction public void add(String flag, String s) { System.out.println("啊我是一个平凡的service,但是我的使命就是要添加一个字符串到db中"); db.mysql.add("哈哈哈哈"); if (flag.equals("true")) { int i = 1 / 0; } } }
当Service调用client时,它发现,没有任何一个拦截器是拦截clinet(),所以他没有走代理对象,走的只是Service.class。然后Service对象调用自己的add()当然也不会走代理对象!那么原因就是client()方法使用的不是代理对象的client()。
接下来我们试试这种。
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package springcode.aop.transactiontest;/* * @auther 顶风少年 * @mail dfsn19970313@foxmail.com * @date 2020-01-28 14:56 * @notify * @version 1.0 */ import org.springframework.beans.factory.annotation.Autowired; import org.springframework.stereotype.Component; @Component public class Service { @Autowired private DB db; @DBTransaction public void client(String flag, String s) { add(flag, "add"); } @DBTransaction public void add(String flag, String s) { System.out.println("啊我是一个平凡的service,但是我的使命就是要添加一个字符串到db中"); db.mysql.add("哈哈哈哈"); if (flag.equals("true")) { int i = 1 / 0; } } }
此时事务虽然生效了,但是并不是add()方法的事务,真正被拦截的是client(),也就是说,在代理类的client中走的是目标类自己的add()。这也就是官方说明的一点,关于所有的this引用都指向的是目标类本身,而非代理对象。对于这种问题的方式官方给出了解决办法。
首先将AopContext上下文暴露出来。@EnableAspectJAutoProxy(exposeProxy=true)然后目标对象中创建代理对象。这种方式粗暴简单说,我要用的就是你的代理对象,没毛病。但是一旦我们换了AOP不用SpringAop了,这种方式肯定是报错的。
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package springcode.aop.transactiontest;/* * @auther 顶风少年 * @mail dfsn19970313@foxmail.com * @date 2020-01-28 14:56 * @notify * @version 1.0 */ import org.springframework.aop.framework.AopContext; import org.springframework.beans.factory.annotation.Autowired; import org.springframework.stereotype.Component; @Component public class Service { @Autowired private DB db; public void client(String flag, String s) { ((Service) AopContext.currentProxy()).add(flag, "add"); } @DBTransaction public void add(String flag, String s) { System.out.println("啊我是一个平凡的service,但是我的使命就是要添加一个字符串到db中"); db.mysql.add("哈哈哈哈"); if (flag.equals("true")) { int i = 1 / 0; } } }
然后,还有一种方式。既然this是本类对象的方法,那么我不用this。手动注入一个本类,通过Spring容器,那么你就要乖乖走代理对象。
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package springcode.aop.transactiontest;/* * @auther 顶风少年 * @mail dfsn19970313@foxmail.com * @date 2020-01-28 14:56 * @notify * @version 1.0 */ import org.springframework.aop.framework.AopContext; import org.springframework.beans.factory.annotation.Autowired; import org.springframework.stereotype.Component; @Component public class Service { @Autowired private DB db; @Autowired private Service service; public void client(String flag, String s) { // ((Service) AopContext.currentProxy()).add(flag, "add"); service.add(flag, "add"); } @DBTransaction public void add(String flag, String s) { System.out.println("啊我是一个平凡的service,但是我的使命就是要添加一个字符串到db中"); db.mysql.add("哈哈哈哈"); if (flag.equals("true")) { int i = 1 / 0; } } }
AspectJ编译器体验
首先我要先吐槽下Spring文档,它对于AspectJ编译器真的一点都不友好!!!这一个Demo是找了好多资料拼拼凑凑完成的。只为了填本类调用的坑!下面代码片段是重新开的项目SpringBoot2.2.4。JDK8。编译器使用的IDEA。这里依然有两个问题我没有解决1、生成的代理Class在哪放?2、为什么@Component注解会失效!
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<?xml version="1.0" encoding="UTF-8"?> <project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 https://maven.apache.org/xsd/maven-4.0.0.xsd"> <modelVersion>4.0.0</modelVersion> <parent> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-parent</artifactId> <version>2.2.4.RELEASE</version> <relativePath/> <!-- lookup parent from repository --> </parent> <groupId>com.datang</groupId> <artifactId>demo</artifactId> <version>0.0.1-SNAPSHOT</version> <name>aspectj</name> <description>Demo project for Spring Boot</description> <properties> <java.version>1.8</java.version> </properties> <dependencies> <dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-aop</artifactId> </dependency> <dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-test</artifactId> <scope>test</scope> </dependency> </dependencies> <build> <plugins> <plugin> <groupId>org.apache.maven.plugins</groupId> <artifactId>maven-surefire-plugin</artifactId> <configuration> <argLine> -javaagent:"${settings.localRepository}/org/aspectj/aspectjweaver/${aspectj.version}/aspectjweaver-${aspectj.version}.jar" -javaagent:"${settings.localRepository}/org/springframework/spring-instrument/5.2.3.RELEASE/spring-instrument-5.2.3.RELEASE.jar" <!-- -Dspring.profiles.active=test--> </argLine> </configuration> </plugin> <plugin> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-maven-plugin</artifactId> <configuration> <agent> ${settings.localRepository}/org/aspectj/aspectjweaver/${aspectj.version}/aspectjweaver-${aspectj.version}.jar </agent> <agent> ${settings.localRepository}/org/springframework/spring-instrument/5.2.3.RELEASE/spring-instrument-5.2.3.RELEASE.jar </agent> </configuration> </plugin> </plugins> </build> </project>
pom文件需要注意的是aspectjweaver和spring-instrument这两个jar。位置不要照着写。
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package com.datang.demo.aspectj;/* * @auther 顶风少年 * @mail dfsn19970313@foxmail.com * @date 2020-01-28 15:26 * @notify * @version 1.0 */ import org.aspectj.lang.ProceedingJoinPoint; import org.aspectj.lang.annotation.Around; import org.aspectj.lang.annotation.Aspect; import org.aspectj.lang.annotation.Pointcut; import org.springframework.beans.factory.annotation.Autowired; @Aspect public class DBTransactionAspect { @Autowired private DB db; @Pointcut("@annotation(com.datang.demo.aspectj.DBTransaction)&&execution(* *(..)) ") public void Pointcut() { } @Around("Pointcut()") public void around(ProceedingJoinPoint pjp) { Object[] args = pjp.getArgs(); for (Object s : args) { String o = (String) s; System.out.println("目标对象方法的参数--"+o); } Object object = null; try { System.out.println("事务开始"); object = pjp.proceed(); System.out.println("事务提交"); } catch (Throwable throwable) { System.out.println(db==null); db.mysql.remove(db.mysql.size() - 1); System.out.println("事务回滚"); } } }
通知类此处还有坑@Component失效!所以我没有加。其次@Pointcut后边也加入了一段这个是为了应对AspectJ的BUG,如果不加在本类调用会被AOP两次!
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package com.datang.demo.aspectj;/* * @auther 顶风少年 * @mail dfsn19970313@foxmail.com * @date 2020-01-28 14:56 * @notify * @version 1.0 */ import org.springframework.beans.factory.annotation.Autowired; import org.springframework.stereotype.Component; @Component public class Service { @Autowired private DB db; public void client(String flag, String s) { this.add(flag, "add...."); } @DBTransaction public void add(String flag, String s) { System.out.println("啊我是一个平凡的service,但是我的使命就是要添加一个字符串到db中"); db.mysql.add("哈哈哈哈"); if (flag.equals("true")) { int i = 1 / 0; } } }
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package com.datang.demo.aspectj; import java.lang.annotation.*; @Target(ElementType.METHOD) @Retention(RetentionPolicy.RUNTIME) @Documented public @interface DBTransaction { }
Service和注解类不变
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package com.datang.demo.aspectj;/* * @auther 顶风少年 * @mail dfsn19970313@foxmail.com * @date 2020-01-29 14:37 * @notify * @version 1.0 */ import org.springframework.context.annotation.ComponentScan; import org.springframework.context.annotation.Configuration; import org.springframework.context.annotation.EnableLoadTimeWeaving; import static org.springframework.context.annotation.EnableLoadTimeWeaving.AspectJWeaving.AUTODETECT; @Configuration @ComponentScan("com.datang.demo.aspectj") @EnableLoadTimeWeaving(aspectjWeaving=AUTODETECT) public class CustomLtwConfig { }
此处用了个Spring配置类,主要为了配置@EnableLoadTimeWeaving(aspectjWeaving=AUTODETECT)这个玩意,启动AspectJ的XML配置。
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<?xml version="1.0" encoding="UTF-8"?> <!DOCTYPE aspectj PUBLIC "-//AspectJ//DTD//EN" "http://www.eclipse.org/aspectj/dtd/aspectj.dtd"> <aspectj> <!--要织入切面的目标类--> <weaver> <include within="com.datang.demo.aspectj..*" /> </weaver> <!--切面类--> <aspects> <aspect name="com.datang.demo.aspectj.DBTransactionAspect" /> </aspects> </aspectj>
这个文件的位置不要放错