基于Spring AOP @AspectJ進階說明
@AspectJ可以使用切點函數定義切點,我們還可以使用邏輯運算符對切點進行復核運算得到復合的切點,為了在切面中重用切點,我們還可以對切點進行命名,以便在其他的地方引用定義過的切點。
當一個連接點匹配多個切點時,需要考慮織入順序的問題,此外一個重要的問題是如何再增強中訪問連接點上下文的信息。
Waiter接口:
package com.yyq.aspectJAdvanced;public interface Waiter { void greetTo(String name); void serveTo(String name);}
NaiveWaiter實現類:
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實現類:
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實現類:
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- /> <bean /> <bean /> <bean /> <!-- <bean /> <bean /> <bean /> <bean /> <bean /> <bean /> <bean /> <bean /> <bean />--></beans>1、切點符合運算
使用切點符合運算符,我們將擁有強大而靈活的切點表達能力。
TestAspect:切點符合運算定義切面
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;@Aspectpublic class TestAspect { //與非運算 @Before('!target(com.yyq.aspectJAdvanced.NaiveWaiter) && execution(* serveTo(..))') public void notServeInNaiveWaiter(){ System.out.println('--notServeInNaiveWaiter() executed!--'); } //與運算 @After('within(com.yyq.aspectJAdvanced.*) && execution(* greetTo(..))') public void greetToFun(){ System.out.println('--greetToFun() executed!--'); } //或運算 @AfterReturning('target(com.yyq.aspectJAdvanced.Waiter) || target(com.yyq.aspectJAdvanced.Seller)') public void waiterOrSeller(){ System.out.println('--waiterOrSeller() executed!--'); }}
測試方法:
@Test public void pointAspectJTest() { String configPath = 'comyyqaspectJAdvancedbeans.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'); }
輸出結果:
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、命名切點
切點直接聲明在增強方法處被稱為匿名切點,匿名切點只能在聲明處使用。如果希望在其他地方重用一個切點,我們可以通過@Pointcut注解以及切面類方法對切點進行命名。
TestNamePointcut:命名切點類
package com.yyq.aspectJAdvanced;import org.aspectj.lang.annotation.Pointcut;public class TestNamePointcut { //通過注解方法inPackage()對該切點進行命名,方法可視域修飾符為private,表明該命名切點只能在本切面類中使用 @Pointcut('within(com.yyq.aspectJAdvaned.*)') private void inPackage(){} @Pointcut('execution(* greetTo(..))') protected void greetTo(){} @Pointcut('inPackage() and greetTo()') public void inPkgGreetTo(){}}
TestAspect2:切面實現類
package com.yyq.aspectJAdvanced;import org.aspectj.lang.annotation.Aspect;import org.aspectj.lang.annotation.Before;@Aspectpublic 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!--'); }}
測試方法:
@Test public void pointAspectJTest2() { String configPath = 'comyyqaspectJAdvancedbeans.xml'; ApplicationContext ctx = new ClassPathXmlApplicationContext(configPath); NaiveWaiter naiveWaiter = (NaiveWaiter) ctx.getBean('naiveWaiter'); naiveWaiter.smile('Andy', 2); }
輸出結果:
--pkgGreetToNotnaiveWaiter() executed!--NaiveWaiter:smile to Andy2times...3、增強織入的順序
一個連接點可以同時匹配多個切點,切點對應的增強在連接點上的織入順序的安排主要有以下3種情況:
1)如果增強在同一個切面類中聲明,則依照增強在切面類中定義的順序進行織入;
2)如何增強位于不同的切面類中,且這些切面類都實現了org.springframework.core.Order接口,則由接口方法的順序號決定(順序號小的先織入);
3)如果增強位于不同的切面類中,且這些切面類沒有實現org.springframework.core.Order接口,織入的順序是不確定的。
4、訪問連接點信息AspectJ使用org.aspectj.lang.JoinPoint接口表示目標類連接點對象,如果是環繞增強時,使用org.aspectj.lang.ProceedingJoinPoint表示連接點對象,該類是JoinPoint的子接口,任何一個增強方法都可以通過將第一個入參聲明為JoinPoint訪問到連接點上下文的信息。
TestAspect3:切面實現類
@Aspectpublic 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---'); }}
測試方法:
@Test public void pointAspectJTest3() { String configPath = 'comyyqaspectJAdvancedbeans.xml'; ApplicationContext ctx = new ClassPathXmlApplicationContext(configPath); Waiter naiveWaiter = (Waiter) ctx.getBean('naiveWaiter'); naiveWaiter.greetTo('Andy'); }
輸出結果:
---joinPointAccess---args[0]:Andysignature:class com.yyq.aspectJAdvanced.NaiveWaiterNaiveWaiter:greet to Andy...---joinPointAccess---5、綁定連接點方法入參
args()用于綁定連接點方法的入參;@annotation()用于綁定連接點方法的注解對象;而@args()用于綁定連接點方法入參的注解。
TestAspect4:切面實現類
@Aspectpublic 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---'); }}
測試方法:
@Test public void pointAspectJTest4() { String configPath = 'comyyqaspectJAdvancedbeans.xml'; ApplicationContext ctx = new ClassPathXmlApplicationContext(configPath); NaiveWaiter naiveWaiter = (NaiveWaiter) ctx.getBean('naiveWaiter'); naiveWaiter.smile('Andy', 3); }
輸出結果:
---bindJoinPointParams---name:Andynum:3---bindJoinPointParams---NaiveWaiter:smile to Andy 3 times...6、綁定代理對象
使用this()或target()可綁定被代理對象實例,在通過類實例名綁定對象時,還依然具有原來連接點匹配的功能,只不過類名是通過增強方法中同名入參的類型間接決定罷了。
TestAspect5:切面實現類
@Aspectpublic class TestAspect5 { @Before('this(waiter)') public void bindProxyObj(Waiter waiter){ System.out.println('---bindProxyObj---'); System.out.println(waiter.getClass().getName()); System.out.println('---bindProxyObj---'); }}
測試方法:
@Test public void pointAspectJTest5() { String configPath = 'comyyqaspectJAdvancedbeans.xml'; ApplicationContext ctx = new ClassPathXmlApplicationContext(configPath); Waiter waiter = (Waiter) ctx.getBean('naiveWaiter'); waiter.greetTo('Yang'); }
輸出結果:
---bindProxyObj---com.yyq.aspectJAdvanced.NaiveWaiter$$EnhancerByCGLIB$$fefafe52---bindProxyObj---NaiveWaiter:greet to Yang...7、綁定類注解對象
@within()和@target()函數可以將目標類的注解對象綁定到增強方法中,我們通過@within()演示注解綁定的操作。
TestAspect6:切面測試類
@Aspectpublic class TestAspect6 { @Before('@within(m)') public void bindTypeAnnoObject(Monitorable m) { System.out.println('---bindTypeAnnoObject---'); System.out.println(m.getClass().getName()); System.out.println('---bindTypeAnnoObject---'); }}
測試方法:
@Test public void pointAspectJTest6() { String configPath = 'comyyqaspectJAdvancedbeans.xml'; ApplicationContext ctx = new ClassPathXmlApplicationContext(configPath); Waiter waiter = (Waiter) ctx.getBean('naiveWaiter2'); ((NaiveWaiter2)waiter).greetTo('Yang'); }
輸出結果:
---bindTypeAnnoObject---$Proxy4---bindTypeAnnoObject---NaiveWaiter:greet to Yang...8、綁定返回值
在后置增強中,我們可以通過returning綁定連接點方法的返回值。
TestAspect7:切面實現類
@Aspectpublic 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---'); }}
測試方法:
@Test public void pointAspectJTest7() { String configPath = 'comyyqaspectJAdvancedbeans.xml'; ApplicationContext ctx = new ClassPathXmlApplicationContext(configPath); SmartSeller seller = (SmartSeller) ctx.getBean('seller'); seller.sell('Beer', 'John'); }
輸出結果:
SmartSeller: sell Beer to John...---bindReturnValue---returnValue:100---bindReturnValue---9、綁定拋出的異常
和通過切點函數綁定連接點信息不同,連接點拋出的異常必須使用AfterThrowing注解的throwing成員進行綁定。
TestAspect8:切面實現類
@Aspectpublic 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---'); }}
測試方法:
@Test public void pointAspectJTest8() { String configPath = 'comyyqaspectJAdvancedbeans.xml'; ApplicationContext ctx = new ClassPathXmlApplicationContext(configPath); SmartSeller seller = (SmartSeller) ctx.getBean('seller'); seller.checkBill(1); }
輸出結果:
---bindException---exception:iae Exception---bindException---
以上為個人經驗,希望能給大家一個參考,也希望大家多多支持好吧啦網。如有錯誤或未考慮完全的地方,望不吝賜教。
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