Spring只支持XML方式而没有实现注解的方式(也叫AspectJ方式)的AOP,所以要使用@Aspect注解,只能引入AspectJ相关的 jar 包 aopalliance-1.0.jar 和 aspectjweaver.jar,这个坑把我给坑惨了。
1、引入相关jar包
2、Spring的配置文件 applicationContext.xml 中引入context、aop对应的命名空间;配置自动扫描的包,同时使切面类中相关方法中的注解生效,需自动地为匹配到的方法所在的类生成代理对象。
<?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" xmlns:context="http://www.springframework.org/schema/context" 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-4.0.xsd http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context-4.0.xsd"> <!-- 配置自动扫描的包 --> <context:component-scan base-package="com.qcc.beans.aop"></context:component-scan> <!-- 自动为切面方法中匹配的方法所在的类生成代理对象。 --> <aop:aspectj-autoproxy></aop:aspectj-autoproxy> </beans>
3、创建简单计算器的接口ArithmeticCalculator.java及实现类ArithmeticCalculatorImpl.java
package com.qcc.beans.aop; public interface ArithmeticCalculator { int add(int i, int j); int sub(int i, int j); int mul(int i, int j); int div(int i, int j); }
package com.qcc.beans.aop; import org.springframework.stereotype.Component; //将实现类加入Spring的IOC容器进行管理 @Component("arithmeticCalculator") public class ArithmeticCalculatorImpl implements ArithmeticCalculator { @Override public int add(int i, int j) { int result = i + j; return result; } @Override public int sub(int i, int j) { int result = i - j; return result; } @Override public int mul(int i, int j) { int result = i * j; return result; } @Override public int div(int i, int j) { int result = i / j; return result; } }
4、现在想在实现类中的每个方法执行前、后、以及是否发生异常等信息打印出来,需要把日志信息抽取出来,写到对应的切面的类中 LoggingAspect.java 中
要想把一个类变成切面类,需要两步,
① 在类上使用 @Component 注解 把切面类加入到IOC容器中
② 在类上使用 @Aspect 注解 使之成为切面类
下面直接上完整代码,用@Aspect注解方式来实现前置通知、返回通知、后置通知、异常通知、环绕通知。
package com.qcc.beans.aop; import java.util.Arrays; 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.springframework.stereotype.Component; /** * 日志切面 * * @author QianChaoChen 00002336<br> * @date 2017年3月3日 下午3:03:29 */ @Component @Aspect public class LoggingAspect { /** * 前置通知:目标方法执行之前执行以下方法体的内容 * @param jp */ @Before("execution(* com.qcc.beans.aop.*.*(..))") public void beforeMethod(JoinPoint jp){ String methodName = jp.getSignature().getName(); System.out.println("【前置通知】the method 【" + methodName + "】 begins with " + Arrays.asList(jp.getArgs())); } /** * 返回通知:目标方法正常执行完毕时执行以下代码 * @param jp * @param result */ @AfterReturning(value="execution(* com.qcc.beans.aop.*.*(..))",returning="result") public void afterReturningMethod(JoinPoint jp, Object result){ String methodName = jp.getSignature().getName(); System.out.println("【返回通知】the method 【" + methodName + "】 ends with 【" + result + "】"); } /** * 后置通知:目标方法执行之后执行以下方法体的内容,不管是否发生异常。 * @param jp */ @After("execution(* com.qcc.beans.aop.*.*(..))") public void afterMethod(JoinPoint jp){ System.out.println("【后置通知】this is a afterMethod advice..."); } /** * 异常通知:目标方法发生异常的时候执行以下代码 */ @AfterThrowing(value="execution(* com.qcc.beans.aop.*.*(..))",throwing="e") public void afterThorwingMethod(JoinPoint jp, NullPointerException e){ String methodName = jp.getSignature().getName(); System.out.println("【异常通知】the method 【" + methodName + "】 occurs exception: " + e); } // /** // * 环绕通知:目标方法执行前后分别执行一些代码,发生异常的时候执行另外一些代码 // * @return // */ // @Around(value="execution(* com.qcc.beans.aop.*.*(..))") // public Object aroundMethod(ProceedingJoinPoint jp){ // String methodName = jp.getSignature().getName(); // Object result = null; // try { // System.out.println("【环绕通知中的--->前置通知】:the method 【" + methodName + "】 begins with " + Arrays.asList(jp.getArgs())); // //执行目标方法 // result = jp.proceed(); // System.out.println("【环绕通知中的--->返回通知】:the method 【" + methodName + "】 ends with " + result); // } catch (Throwable e) { // System.out.println("【环绕通知中的--->异常通知】:the method 【" + methodName + "】 occurs exception " + e); // } // // System.out.println("【环绕通知中的--->后置通知】:-----------------end.----------------------"); // return result; // } }
5、编写Main方法进行测试
package com.qcc.beans.aop; import org.springframework.context.ApplicationContext; import org.springframework.context.support.ClassPathXmlApplicationContext; public class Main { public static void main(String[] args) { ApplicationContext ctx = new ClassPathXmlApplicationContext("applicationContext.xml"); ArithmeticCalculator arithmeticCalculator = (ArithmeticCalculator) ctx.getBean("arithmeticCalculator"); System.out.println(arithmeticCalculator.getClass()); int result = arithmeticCalculator.add(3, 5); System.out.println("result: " + result); result = arithmeticCalculator.div(5, 0); System.out.println("result: " + result); } }
运行结果:
class com.sun.proxy.$Proxy10 【前置通知】the method 【add】 begins with [3, 5] 【后置通知】this is a afterMethod advice... 【返回通知】the method 【add】 ends with 【8】 result: 8 【前置通知】the method 【div】 begins with [5, 0] 【后置通知】this is a afterMethod advice... Exception in thread "main" java.lang.ArithmeticException: / by zero at com.qcc.beans.aop.ArithmeticCalculatorImpl.div(ArithmeticCalculatorImpl.java:28) at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57) at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) at java.lang.reflect.Method.invoke(Method.java:606) at org.springframework.aop.support.AopUtils.invokeJoinpointUsingReflection(AopUtils.java:317) at org.springframework.aop.framework.ReflectiveMethodInvocation.invokeJoinpoint(ReflectiveMethodInvocation.java:190) at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:157) at org.springframework.aop.framework.adapter.MethodBeforeAdviceInterceptor.invoke(MethodBeforeAdviceInterceptor.java:52) at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:179) at org.springframework.aop.aspectj.AspectJAfterAdvice.invoke(AspectJAfterAdvice.java:43) at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:179) at org.springframework.aop.framework.adapter.AfterReturningAdviceInterceptor.invoke(AfterReturningAdviceInterceptor.java:52) at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:179) at org.springframework.aop.aspectj.AspectJAfterThrowingAdvice.invoke(AspectJAfterThrowingAdvice.java:58) at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:179) at org.springframework.aop.interceptor.ExposeInvocationInterceptor.invoke(ExposeInvocationInterceptor.java:92) at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:179) at org.springframework.aop.framework.JdkDynamicAopProxy.invoke(JdkDynamicAopProxy.java:207) at com.sun.proxy.$Proxy10.div(Unknown Source) at com.qcc.beans.aop.Main.main(Main.java:15)
把其它代码都注释掉,把环绕通知的方法释放出来,测试结果如下:
【环绕通知中的--->前置通知】:the method 【add】 begins with [3, 5] 【环绕通知中的--->返回通知】:the method 【add】 ends with 8 【环绕通知中的--->后置通知】:-----------------end.---------------------- result: 8 【环绕通知中的--->前置通知】:the method 【div】 begins with [5, 0] 【环绕通知中的--->异常通知】:the method 【div】 occurs exception java.lang.ArithmeticException: / by zero 【环绕通知中的--->后置通知】:-----------------end.---------------------- Exception in thread "main" org.springframework.aop.AopInvocationException: Null return value from advice does not match primitive return type for: public abstract int com.qcc.beans.aop.ArithmeticCalculator.div(int,int) at org.springframework.aop.framework.JdkDynamicAopProxy.invoke(JdkDynamicAopProxy.java:219) at com.sun.proxy.$Proxy7.div(Unknown Source) at com.qcc.beans.aop.Main.main(Main.java:15)
从以上发现,返回通知和异常通知不会同时出现;不管是否发生异常,后置通知都会正常打印。
补充:基于@Aspect实现AOP的两种方式
package com.anno; import java.lang.annotation.ElementType; import java.lang.annotation.Retention; import java.lang.annotation.RetentionPolicy; import java.lang.annotation.Target; @Retention(RetentionPolicy.RUNTIME) //什么时候运行和结束 @Target( {ElementType.METHOD , ElementType.TYPE}) //能放在哪里. public @interface AnnotationTwo { } package com.anno; 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.context.annotation.EnableAspectJAutoProxy; import org.springframework.stereotype.Component; @Aspect @Component @EnableAspectJAutoProxy public class AspectAnnotationTOW { @Pointcut("@annotation(AnnotationTwo)") public void aspectTow(){ } @Around("aspectTow()") public void aspectservice(ProceedingJoinPoint joinPoint){ System.out.println(111); try { Object proceed = joinPoint.proceed(); } catch (Throwable e) { e.printStackTrace(); } } }
package com.testAnnotation; import java.lang.annotation.ElementType; import java.lang.annotation.Retention; import java.lang.annotation.RetentionPolicy; import java.lang.annotation.Target; @Retention(RetentionPolicy.RUNTIME) //什么时候运行和结束 @Target( {ElementType.METHOD , ElementType.TYPE}) //能放在哪里. public @interface AnnotationOfTest { public String say(); public long howLong() default Long.MAX_VALUE; } package com.testAnnotation; import org.aspectj.lang.ProceedingJoinPoint; import org.aspectj.lang.annotation.Around; import org.aspectj.lang.annotation.Aspect; import org.springframework.context.annotation.EnableAspectJAutoProxy; import org.springframework.stereotype.Component; import com.rabbitmq.tools.jsonrpc.ProcedureDescription; @Component @EnableAspectJAutoProxy @Aspect public class AspectAnnotation { @Around("@annotation(annotationOfTest)") public Object interceptor(ProceedingJoinPoint pjp, AnnotationOfTest annotationOfTest ) { String say = annotationOfTest.say(); long howlong = annotationOfTest.howLong(); try { System.out.println(say+"\t"+howlong); Object object = pjp.proceed(); return object; } catch (Throwable e) { e.printStackTrace(); } return null; } }
<?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:util="http://www.springframework.org/schema/util" xmlns:p="http://www.springframework.org/schema/p" xmlns:aop="http://www.springframework.org/schema/aop" xmlns:tx="http://www.springframework.org/schema/tx" xmlns:context="http://www.springframework.org/schema/context" xsi:schemaLocation=" http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-4.3.xsd http://www.springframework.org/schema/util http://www.springframework.org/schema/util/spring-util-4.3.xsd http://www.springframework.org/schema/tx http://www.springframework.org/schema/tx/spring-tx-4.3.xsd http://www.springframework.org/schema/aop http://www.springframework.org/schema/aop/spring-aop-4.3.xsd http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context-4.3.xsd"> <context:component-scan base-package="com.testAnnotation"></context:component-scan> <context:component-scan base-package="com.service"></context:component-scan> <context:component-scan base-package="com.anno"></context:component-scan> <aop:aspectj-autoproxy proxy-target-class="true"></aop:aspectj-autoproxy> </beans> service: package com.service; import java.util.Date; import org.springframework.stereotype.Service; import com.anno.AnnotationTwo; import com.testAnnotation.AnnotationOfTest; @Service public class service { @AnnotationTwo public void go() { System.out.println(new Date().toLocaleString()); } }
package com.test; import org.springframework.context.ApplicationContext; import org.springframework.context.support.ClassPathXmlApplicationContext; import com.service.service; import com.testAnnotation.AnnotationOfTest; public class Test { public static void main(String[] args) { ApplicationContext applicationContext = new ClassPathXmlApplicationContext("applicationContext.xml"); service bean = applicationContext.getBean(service.class); bean.go(); } }
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