Spring入门第二十课
Posted alittlecomputer
tags:
篇首语：本文由小常识网(cha138.com)小编为大家整理，主要介绍了Spring入门第二十课相关的知识，希望对你有一定的参考价值。
返回通知，异常通知，环绕通知
看代码：
package logan.study.aop.impl; 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 logan.study.aop.impl; import org.springframework.stereotype.Component; @Component public class ArithmeticCalculatorImpl implements ArithmeticCalculator { @Override public int add(int i, int j) { // TODO Auto-generated method stub int result = i + j; return result; } @Override public int sub(int i, int j) { // TODO Auto-generated method stub int result = i - j; return result; } @Override public int mul(int i, int j) { // TODO Auto-generated method stub int result = i * j; return result; } @Override public int div(int i, int j) { // TODO Auto-generated method stub int result = i / j; return result; } }
package logan.study.aop.impl; import java.util.Arrays; import java.util.List; import org.aspectj.lang.JoinPoint; import org.aspectj.lang.annotation.After; import org.aspectj.lang.annotation.AfterReturning; import org.aspectj.lang.annotation.AfterThrowing; import org.aspectj.lang.annotation.Aspect; import org.aspectj.lang.annotation.Before; import org.springframework.stereotype.Component; //把这个类声明为一个切面：需要把该类放入到IOC容器中，在声明为一个切面 @Aspect @Component public class LoggingAspect { //声明该方法时一个前置通知：在目标方法开始之前执行 @Before("execution(public int logan.study.aop.impl.ArithmeticCalculator.*(int, int))") public void beforeMethod(JoinPoint joinPoint){ String methodName = joinPoint.getSignature().getName(); List<Object> args = Arrays.asList(joinPoint.getArgs()); System.out.println("The method "+ methodName +" begins with "+args); } //后置通知，在目标方法执行之后执行（无论该方法是否出现异常） //在后置通知中，还不能访问目标方法执行的结果，执行结果在返回通知中可以访问 @After("execution(public int logan.study.aop.impl.ArithmeticCalculator.*(int, int))") public void afterMethod(JoinPoint joinPoint){ String methodName = joinPoint.getSignature().getName(); List<Object> args = Arrays.asList(joinPoint.getArgs()); System.out.println("The method "+ methodName +" ends with "+args); } //返回通知，在方法正常结束时执行的代码 //返回通知是可以访问返回值的 @AfterReturning(value="execution(public int logan.study.aop.impl.ArithmeticCalculator.*(int, int))", returning="result") public void afterReturningMethod(JoinPoint joinPoint,Object result){ String methodName = joinPoint.getSignature().getName(); System.out.println("The method "+ methodName +" ends with "+result); } //异常通知，在方法抛出异常时调用 @AfterThrowing(value="execution(public int logan.study.aop.impl.ArithmeticCalculator.*(int, int))", throwing="ex") public void afterThrowingMethod(JoinPoint joinPoint,Exception ex){ String methodName = joinPoint.getSignature().getName(); System.out.println("The method "+ methodName +" occus with "+ex); } }
<?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-4.3.xsd http://www.springframework.org/schema/aop http://www.springframework.org/schema/aop/spring-aop-4.3.xsd"> <context:component-scan base-package="logan.study.aop.impl"></context:component-scan> <aop:aspectj-autoproxy></aop:aspectj-autoproxy> </beans>
package logan.study.aop.impl; import org.springframework.context.ApplicationContext; import org.springframework.context.support.ClassPathXmlApplicationContext; public class Main { public static void main(String[] args) { // TODO Auto-generated method stub //1.创建Spring的IOC容器 ApplicationContext ctx = new ClassPathXmlApplicationContext("applicationContext.xml"); //2.从IOC容器里面获取bean实例 ArithmeticCalculator arithmeticCalculator = ctx.getBean(ArithmeticCalculator.class); //使用Bean int result = arithmeticCalculator.add(3, 6); System.out.println(result); result = arithmeticCalculator.div(3, 0); System.out.println(result); } }
执行结果：
五月 28, 2017 6:23:42 上午 org.springframework.context.support.ClassPathXmlApplicationContext prepareRefresh 信息: Refreshing org[email protected]49c2faae: startup date [Sun May 28 06:23:42 CST 2017]; root of context hierarchy 五月 28, 2017 6:23:42 上午 org.springframework.beans.factory.xml.XmlBeanDefinitionReader loadBeanDefinitions 信息: Loading XML bean definitions from class path resource [applicationContext.xml] The method add begins with [3, 6] The method add ends with [3, 6] The method add ends with 9 9 The method div begins with [3, 0] The method div ends with [3, 0] The method div occus with java.lang.ArithmeticException: / by zero Exception in thread "main" java.lang.ArithmeticException: / by zero at logan.study.aop.impl.ArithmeticCalculatorImpl.div(ArithmeticCalculatorImpl.java:32) at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) at java.lang.reflect.Method.invoke(Method.java:498) at org.springframework.aop.support.AopUtils.invokeJoinpointUsingReflection(AopUtils.java:333) 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:47) 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:62) 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:213) at com.sun.proxy.$Proxy10.div(Unknown Source) at logan.study.aop.impl.Main.main(Main.java:18)
在这里稍微改改代码：我们把异常改成空指针异常
package logan.study.aop.impl; import java.util.Arrays; import java.util.List; import org.aspectj.lang.JoinPoint; import org.aspectj.lang.annotation.After; import org.aspectj.lang.annotation.AfterReturning; import org.aspectj.lang.annotation.AfterThrowing; import org.aspectj.lang.annotation.Aspect; import org.aspectj.lang.annotation.Before; import org.springframework.stereotype.Component; //把这个类声明为一个切面：需要把该类放入到IOC容器中，在声明为一个切面 @Aspect @Component public class LoggingAspect { //声明该方法时一个前置通知：在目标方法开始之前执行 @Before("execution(public int logan.study.aop.impl.ArithmeticCalculator.*(int, int))") public void beforeMethod(JoinPoint joinPoint){ String methodName = joinPoint.getSignature().getName(); List<Object> args = Arrays.asList(joinPoint.getArgs()); System.out.println("The method "+ methodName +" begins with "+args); } //后置通知，在目标方法执行之后执行（无论该方法是否出现异常） //在后置通知中，还不能访问目标方法执行的结果，执行结果在返回通知中可以访问 @After("execution(public int logan.study.aop.impl.ArithmeticCalculator.*(int, int))") public void afterMethod(JoinPoint joinPoint){ String methodName = joinPoint.getSignature().getName(); List<Object> args = Arrays.asList(joinPoint.getArgs()); System.out.println("The method "+ methodName +" ends with "+args); } //返回通知，在方法正常结束时执行的代码 //返回通知是可以访问返回值的 @AfterReturning(value="execution(public int logan.study.aop.impl.ArithmeticCalculator.*(int, int))", returning="result") public void afterReturningMethod(JoinPoint joinPoint,Object result){ String methodName = joinPoint.getSignature().getName(); System.out.println("The method "+ methodName +" ends with "+result); } //异常通知，在方法抛出异常时调用 @AfterThrowing(value="execution(public int logan.study.aop.impl.ArithmeticCalculator.*(int, int))", throwing="ex") public void afterThrowingMethod(JoinPoint joinPoint,NullPointerException ex){ String methodName = joinPoint.getSignature().getName(); System.out.println("The method "+ methodName +" occus with "+ex); } }
执行结果：
五月 28, 2017 6:28:32 上午 org.springframework.context.support.ClassPathXmlApplicationContext prepareRefresh 信息: Refreshing org[email protected]49c2faae: startup date [Sun May 28 06:28:32 CST 2017]; root of context hierarchy 五月 28, 2017 6:28:32 上午 org.springframework.beans.factory.xml.XmlBeanDefinitionReader loadBeanDefinitions 信息: Loading XML bean definitions from class path resource [applicationContext.xml] The method add begins with [3, 6] The method add ends with [3, 6] The method add ends with 9 9 The method div begins with [3, 0] The method div ends with [3, 0] Exception in thread "main" java.lang.ArithmeticException: / by zero at logan.study.aop.impl.ArithmeticCalculatorImpl.div(ArithmeticCalculatorImpl.java:32) at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) at java.lang.reflect.Method.invoke(Method.java:498) at org.springframework.aop.support.AopUtils.invokeJoinpointUsingReflection(AopUtils.java:333) 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:47) 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:62) 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:213) at com.sun.proxy.$Proxy10.div(Unknown Source) at logan.study.aop.impl.Main.main(Main.java:18)
可以看到异常通知没有执行。只有当发生空指针异常时才会执行。
下面看环绕通知：
package logan.study.aop.impl; import java.util.Arrays; import java.util.List; 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; //把这个类声明为一个切面：需要把该类放入到IOC容器中，在声明为一个切面 @Aspect @Component public class LoggingAspect { /** * 环绕通知需要携带ProceedingJoinPoint类型的参数 * 环绕通知类似于动态代理的全过程：ProceedingJoinPoint类型的参数可以决定是否执行目标方法 * 且环绕通知必须有返回值，返回值即为目标方法的返回值 */ @Around("execution(public int logan.study.aop.impl.ArithmeticCalculator.*(int, int))") public Object aroundMethod(ProceedingJoinPoint pjd){ Object result = null; String methodName = pjd.getSignature().getName(); //执行目标方法 try{ //前置通知 System.out.println("The method" + methodName + " begins with " + Arrays.asList(pjd.getArgs())); result = pjd.proceed(); //返回通知 System.out.println("The method" + methodName + " ends with " + result); }catch(Throwable e){ //异常通知 System.out.println("The method occurs exception:" + e); } //后置通知 System.out.println("The method " + methodName + "ends"); return result; } }
package logan.study.aop.impl; import org.springframework.context.ApplicationContext; import org.springframework.context.support.ClassPathXmlApplicationContext; public class Main { public static void main(String[] args) { // TODO Auto-generated method stub //1.创建Spring的IOC容器 ApplicationContext ctx = new ClassPathXmlApplicationContext("applicationContext.xml"); //2.从IOC容器里面获取bean实例 ArithmeticCalculator arithmeticCalculator = ctx.getBean(ArithmeticCalculator.class); //使用Bean int result = arithmeticCalculator.add(3, 6); System.out.println(result); result = arithmeticCalculator.div(3, 0); System.out.println(result); } }
返回结果：
五月 28, 2017 6:51:09 上午 org.springframework.context.support.ClassPathXmlApplicationContext prepareRefresh 信息: Refreshing org[email protected]49c2faae: startup date [Sun May 28 06:51:09 CST 2017]; root of context hierarchy 五月 28, 2017 6:51:09 上午 org.springframework.beans.factory.xml.XmlBeanDefinitionReader loadBeanDefinitions 信息: Loading XML bean definitions from class path resource [applicationContext.xml] The methodadd begins with [3, 6] The methodadd ends with 9 The method addends 9 The methoddiv begins with [3, 0] The method occurs exception:java.lang.ArithmeticException: / by zero The method divends Exception in thread "main" org.springframework.aop.AopInvocationException: Null return value from advice does not match primitive return type for: public abstract int logan.study.aop.impl.ArithmeticCalculator.div(int,int) at org.springframework.aop.framework.JdkDynamicAopProxy.invoke(JdkDynamicAopProxy.java:227) at com.sun.proxy.$Proxy7.div(Unknown Source) at logan.study.aop.impl.Main.main(Main.java:18)
环绕通知一般来说不常用。
以上是关于Spring入门第二十课的主要内容，如果未能解决你的问题，请参考以下文章