@AspectJ可以使用切点函数定义切点,我们还可以使用逻辑运算符对切点进行复核运算得到复合的切点,为了在切面中重用切点,我们还可以对切点进行命名,以便在其他的地方引用定义过的切点。
当一个连接点匹配多个切点时,需要考虑织入顺序的问题,此外一个重要的问题是如何再增强中访问连接点上下文的信息。
Waiter接口:
package com.yyq.aspectJAdvanced; public interface Waiter { void greetTo(String name); void serveTo(String name); }
NaiveWaiter实现类:
package com.yyq.aspectJAdvanced; public class NaiveWaiter implements Waiter { @Override public void greetTo(String name) { System.out.println("NaiveWaiter:greet to " + name + "..."); } @Override public void serveTo(String name) { System.out.println("NaiveWaiter:serving to " + name + "..."); } public void smile(String clientName,int times){ System.out.println("NaiveWaiter:smile to "+clientName+ times+"times..."); } }
NaughtyWaiter实现类:
package com.yyq.aspectJAdvanced; public class NaughtyWaiter implements Waiter { public void greetTo(String clientName) { System.out.println("NaughtyWaiter:greet to " + clientName + "..."); } public void serveTo(String clientName) { System.out.println("NaughtyWaiter:serving " + clientName + "..."); } public void joke(String clientName, int times) { System.out.println("NaughtyWaiter:play " + times + " jokes to " + clientName + "..."); } }
Seller接口:
package com.yyq.aspectJAdvanced; public interface Seller { int sell(String goods, String clientName); }
SmallSeller实现类:
package com.yyq.aspectJAdvanced; public class SmartSeller implements Seller { public int sell(String goods,String clientName) { System.out.println("SmartSeller: sell "+goods +" to "+clientName+"..."); return 100; } public void checkBill(int billId){ if(billId == 1) throw new IllegalArgumentException("iae Exception"); else throw new RuntimeException("re Exception"); } }
beans.xml配置文件:
<?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-3.0.xsd http://www.springframework.org/schema/aop http://www.springframework.org/schema/aop/spring-aop-3.0.xsd"> <aop:aspectj-autoproxy proxy-target-class="true"/> <bean id="naiveWaiter" class="com.yyq.aspectJAdvanced.NaiveWaiter"/> <bean id="naughtyWaiter" class="com.yyq.aspectJAdvanced.NaughtyWaiter"/> <bean id="seller" class="com.yyq.aspectJAdvanced.SmartSeller"/> <!-- <bean class="com.yyq.aspectJAdvanced.TestAspect"/> <bean class="com.yyq.aspectJAdvanced.TestAspect2"/> <bean class="com.yyq.aspectJAdvanced.TestAspect3"/> <bean class="com.yyq.aspectJAdvanced.TestAspect4"/> <bean class="com.yyq.aspectJAdvanced.TestAspect5"/> <bean id="naiveWaiter2" class="com.yyq.aspectJAdvanced.NaiveWaiter2"/> <bean class="com.yyq.aspectJAdvanced.TestAspect6"/> <bean class="com.yyq.aspectJAdvanced.TestAspect7"/> <bean class="com.yyq.aspectJAdvanced.TestAspect8"/> --> </beans>
1、切点符合运算
使用切点符合运算符,我们将拥有强大而灵活的切点表达能力。
TestAspect:切点符合运算定义切面
package com.yyq.aspectJAdvanced; import org.aspectj.lang.annotation.After; import org.aspectj.lang.annotation.AfterReturning; import org.aspectj.lang.annotation.Aspect; import org.aspectj.lang.annotation.Before; @Aspect public class TestAspect { //与非运算 @Before("!target(com.yyq.aspectJAdvanced.NaiveWaiter) && execution(* serveTo(..))") public void notServeInNaiveWaiter(){ System.out.println("--notServeInNaiveWaiter() executed!--"); } //与运算 @After("within(com.yyq.aspectJAdvanced.*) && execution(* greetTo(..))") public void greetToFun(){ System.out.println("--greetToFun() executed!--"); } //或运算 @AfterReturning("target(com.yyq.aspectJAdvanced.Waiter) || target(com.yyq.aspectJAdvanced.Seller)") public void waiterOrSeller(){ System.out.println("--waiterOrSeller() executed!--"); } }
测试方法:
@Test public void pointAspectJTest() { String configPath = "com\\yyq\\aspectJAdvanced\\beans.xml"; ApplicationContext ctx = new ClassPathXmlApplicationContext(configPath); Waiter naiveWaiter = (Waiter) ctx.getBean("naiveWaiter"); Waiter naughtyWaiter = (Waiter) ctx.getBean("naughtyWaiter"); naiveWaiter.greetTo("John"); naiveWaiter.serveTo("John"); naughtyWaiter.greetTo("Tom"); naughtyWaiter.serveTo("Tom"); }
输出结果:
NaiveWaiter:greet to John... --greetToFun() executed!-- --waiterOrSeller() executed!-- NaiveWaiter:serving to John... --waiterOrSeller() executed!-- NaughtyWaiter:greet to Tom... --greetToFun() executed!-- --waiterOrSeller() executed!-- --notServeInNaiveWaiter() executed!-- NaughtyWaiter:serving Tom... --waiterOrSeller() executed!--
2、命名切点
切点直接声明在增强方法处被称为匿名切点,匿名切点只能在声明处使用。如果希望在其他地方重用一个切点,我们可以通过@Pointcut注解以及切面类方法对切点进行命名。
TestNamePointcut:命名切点类
package com.yyq.aspectJAdvanced; import org.aspectj.lang.annotation.Pointcut; public class TestNamePointcut { //通过注解方法inPackage()对该切点进行命名,方法可视域修饰符为private,表明该命名切点只能在本切面类中使用 @Pointcut("within(com.yyq.aspectJAdvaned.*)") private void inPackage(){} @Pointcut("execution(* greetTo(..))") protected void greetTo(){} @Pointcut("inPackage() and greetTo()") public void inPkgGreetTo(){} }
TestAspect2:切面实现类
package com.yyq.aspectJAdvanced; import org.aspectj.lang.annotation.Aspect; import org.aspectj.lang.annotation.Before; @Aspect public class TestAspect2 { @Before("TestNamePointcut.inPkgGreetTo()") public void pkgGreetTo(){ System.out.println("--pkgGreetTo() executed!--"); } @Before("target(com.yyq.aspectJAdvanced.NaiveWaiter) || TestNamePointcut.inPkgGreetTo()") public void pkgGreetToNotnaiveWaiter(){ System.out.println("--pkgGreetToNotnaiveWaiter() executed!--"); } }
测试方法:
@Test public void pointAspectJTest2() { String configPath = "com\\yyq\\aspectJAdvanced\\beans.xml"; ApplicationContext ctx = new ClassPathXmlApplicationContext(configPath); NaiveWaiter naiveWaiter = (NaiveWaiter) ctx.getBean("naiveWaiter"); naiveWaiter.smile("Andy", 2); }
输出结果:
--pkgGreetToNotnaiveWaiter() executed!-- NaiveWaiter:smile to Andy2times...
3、增强织入的顺序
一个连接点可以同时匹配多个切点,切点对应的增强在连接点上的织入顺序的安排主要有以下3种情况:
1)如果增强在同一个切面类中声明,则依照增强在切面类中定义的顺序进行织入;
2)如何增强位于不同的切面类中,且这些切面类都实现了org.springframework.core.Order接口,则由接口方法的顺序号决定(顺序号小的先织入);
3)如果增强位于不同的切面类中,且这些切面类没有实现org.springframework.core.Order接口,织入的顺序是不确定的。
4、访问连接点信息
AspectJ使用org.aspectj.lang.JoinPoint接口表示目标类连接点对象,如果是环绕增强时,使用org.aspectj.lang.ProceedingJoinPoint表示连接点对象,该类是JoinPoint的子接口,任何一个增强方法都可以通过将第一个入参声明为JoinPoint访问到连接点上下文的信息。
TestAspect3:切面实现类
@Aspect public class TestAspect3 { @Around("execution(* greetTo(..)) && target(com.yyq.aspectJAdvanced.NaiveWaiter)") public void joinPointAccess(ProceedingJoinPoint pjp) throws Throwable { System.out.println("---joinPointAccess---"); System.out.println("args[0]:" + pjp.getArgs()[0]); System.out.println("signature:" + pjp.getTarget().getClass()); pjp.proceed(); System.out.println("---joinPointAccess---"); } }
测试方法:
@Test public void pointAspectJTest3() { String configPath = "com\\yyq\\aspectJAdvanced\\beans.xml"; ApplicationContext ctx = new ClassPathXmlApplicationContext(configPath); Waiter naiveWaiter = (Waiter) ctx.getBean("naiveWaiter"); naiveWaiter.greetTo("Andy"); }
输出结果:
---joinPointAccess--- args[0]:Andy signature:class com.yyq.aspectJAdvanced.NaiveWaiter NaiveWaiter:greet to Andy... ---joinPointAccess---
5、绑定连接点方法入参
args()用于绑定连接点方法的入参;@annotation()用于绑定连接点方法的注解对象;而@args()用于绑定连接点方法入参的注解。
TestAspect4:切面实现类
@Aspect public class TestAspect4 { @Before("target(com.yyq.aspectJAdvanced.NaiveWaiter) && args(name,num,..)") public void bindJoinPointParams(int num, String name) { System.out.println("---bindJoinPointParams---"); System.out.println("name:" + name); System.out.println("num:" + num); System.out.println("---bindJoinPointParams---"); } }
测试方法:
@Test public void pointAspectJTest4() { String configPath = "com\\yyq\\aspectJAdvanced\\beans.xml"; ApplicationContext ctx = new ClassPathXmlApplicationContext(configPath); NaiveWaiter naiveWaiter = (NaiveWaiter) ctx.getBean("naiveWaiter"); naiveWaiter.smile("Andy", 3); }
输出结果:
---bindJoinPointParams--- name:Andy num:3 ---bindJoinPointParams--- NaiveWaiter:smile to Andy 3 times...
6、绑定代理对象
使用this()或target()可绑定被代理对象实例,在通过类实例名绑定对象时,还依然具有原来连接点匹配的功能,只不过类名是通过增强方法中同名入参的类型间接决定罢了。
TestAspect5:切面实现类
@Aspect public class TestAspect5 { @Before("this(waiter)") public void bindProxyObj(Waiter waiter){ System.out.println("---bindProxyObj---"); System.out.println(waiter.getClass().getName()); System.out.println("---bindProxyObj---"); } }
测试方法:
@Test public void pointAspectJTest5() { String configPath = "com\\yyq\\aspectJAdvanced\\beans.xml"; ApplicationContext ctx = new ClassPathXmlApplicationContext(configPath); Waiter waiter = (Waiter) ctx.getBean("naiveWaiter"); waiter.greetTo("Yang"); }
输出结果:
---bindProxyObj--- com.yyq.aspectJAdvanced.NaiveWaiter$$EnhancerByCGLIB$$fefafe52 ---bindProxyObj--- NaiveWaiter:greet to Yang...
7、绑定类注解对象
@within()和@target()函数可以将目标类的注解对象绑定到增强方法中,我们通过@within()演示注解绑定的操作。
TestAspect6:切面测试类
@Aspect public class TestAspect6 { @Before("@within(m)") public void bindTypeAnnoObject(Monitorable m) { System.out.println("---bindTypeAnnoObject---"); System.out.println(m.getClass().getName()); System.out.println("---bindTypeAnnoObject---"); } }
测试方法:
@Test public void pointAspectJTest6() { String configPath = "com\\yyq\\aspectJAdvanced\\beans.xml"; ApplicationContext ctx = new ClassPathXmlApplicationContext(configPath); Waiter waiter = (Waiter) ctx.getBean("naiveWaiter2"); ((NaiveWaiter2)waiter).greetTo("Yang"); }
输出结果:
---bindTypeAnnoObject--- $Proxy4 ---bindTypeAnnoObject--- NaiveWaiter:greet to Yang...
8、绑定返回值
在后置增强中,我们可以通过returning绑定连接点方法的返回值。
TestAspect7:切面实现类
@Aspect public class TestAspect7 { @AfterReturning(value = "target(com.yyq.aspectJAdvanced.SmartSeller)", returning = "retVal") public void bindReturnValue(int retVal) { System.out.println("---bindReturnValue---"); System.out.println("returnValue:" + retVal); System.out.println("---bindReturnValue---"); } }
测试方法:
@Test public void pointAspectJTest7() { String configPath = "com\\yyq\\aspectJAdvanced\\beans.xml"; ApplicationContext ctx = new ClassPathXmlApplicationContext(configPath); SmartSeller seller = (SmartSeller) ctx.getBean("seller"); seller.sell("Beer", "John"); }
输出结果:
SmartSeller: sell Beer to John... ---bindReturnValue--- returnValue:100 ---bindReturnValue---
9、绑定抛出的异常
和通过切点函数绑定连接点信息不同,连接点抛出的异常必须使用AfterThrowing注解的throwing成员进行绑定。
TestAspect8:切面实现类
@Aspect public class TestAspect8 { @AfterThrowing(value = "target(com.yyq.aspectJAdvanced.SmartSeller)", throwing = "iae") public void bindException(IllegalArgumentException iae) { System.out.println("---bindException---"); System.out.println("exception:" + iae.getMessage()); System.out.println("---bindException---"); } }
测试方法:
@Test public void pointAspectJTest8() { String configPath = "com\\yyq\\aspectJAdvanced\\beans.xml"; ApplicationContext ctx = new ClassPathXmlApplicationContext(configPath); SmartSeller seller = (SmartSeller) ctx.getBean("seller"); seller.checkBill(1); }
输出结果:
---bindException--- exception:iae Exception ---bindException---
以上为个人经验,希望能给大家一个参考,也希望大家多多支持易盾网络。如有错误或未考虑完全的地方,望不吝赐教。