1. WIKI教程
2. 学习Spring AOP
3. Spring AOP - After Throwing Advice

Spring AOP - After Throwing Advice

@AfterThrowing是一种通知类型，可确保在方法抛出异常时运行通知。 以下是@AfterThrowing建议的语法。

语法 (Syntax)

@AfterThrowing(PointCut = "execution(* com.iowiki.Student.*(..))", 
   throwing = "error")
public void afterThrowingAdvice(JoinPoint jp, Throwable error){
   System.out.println("Method Signature: "  + jp.getSignature());  
   System.out.println("Exception: "+error);  
}

Where,

• @AfterThrowing - 如果方法抛出异常，则将函数标记为在PointCut覆盖的方法之前执行的建议。

• PointCut - 提供用于选择函数的表达式。

• execution( expression ) - 覆盖要应用建议的方法的表达式。

• throwing - 要返回的异常的名称。

为了理解上述与@AfterThrowing建议相关的概念，让我们编写一个实现@AfterThrowing建议的例子。 要编写我们的示例并提供一些建议，让我们使用一个可用的Eclipse IDE，并使用以下步骤创建一个Spring应用程序。

步	描述
1	更新项目Student根据Spring AOP - Application章节创建。
2	更新bean配置并运行应用程序，如下所述。

以下是Logging.java文件的内容。 这实际上是方面模块的一个示例，它定义了在各个点调用的方法。

package com.iowiki;
import org.aspectj.lang.annotation.Aspect;
import org.aspectj.lang.JoinPoint;  
import org.aspectj.lang.annotation.AfterThrowing;  
@Aspect
public class Logging {
   /** 
    * This is the method which I would like to execute
    * after a selected method execution throws exception.
    */
   @AfterThrowing(PointCut = "execution(* com.iowiki.Student.*(..))", 
      throwing = "error")
   public void afterThrowingAdvice(JoinPoint jp, Throwable error){
      System.out.println("Method Signature: "  + jp.getSignature());  
      System.out.println("Exception: "+error);  
   }
}

以下是Student.java文件的内容。

package com.iowiki;
public class Student {
   private Integer age;
   private String name;
   public void setAge(Integer age) {
      this.age = age;
   }
   public Integer getAge() {
      System.out.println("Age : " + age );
      return age;
   }
   public void setName(String name) {
      this.name = name;
   }
   public String getName() {
      System.out.println("Name : " + name );
      return name;
   }
   public void printThrowException(){
      System.out.println("Exception raised");
      throw new IllegalArgumentException();
   }
}

以下是MainApp.java文件的内容。

package com.iowiki;
import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;
public class MainApp {
   public static void main(String[] args) {
      ApplicationContext context = 
         new ClassPathXmlApplicationContext("Beans.xml");
      Student student = (Student) context.getBean("student");
      student.printThrowException();     
   }
}

以下是配置文件Beans.xml 。

<?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/>
   <!-- Definition for student bean -->
   <bean id = "student" class = "com.iowiki.Student">
      <property name = "name"  value = "Zara" />
      <property name = "age"  value = "11"/>      
   </bean>
   <!-- Definition for logging aspect -->
   <bean id = "logging" class = "com.iowiki.Logging"/> 
</beans>

运行项目 (Run Project)

完成源和配置文件的创建后，运行您的应用程序。 右键单击应用程序中的MainApp.java，并使用run as Java Application命令。 如果您的应用程序一切正常，它将打印以下消息。

Exception raised
Method Signature: void com.iowiki.Student.printThrowException()
Exception: java.lang.IllegalArgumentException
Exception in thread "main" java.lang.IllegalArgumentException
   at com.iowiki.Student.printThrowException(Student.java:25)
   at com.iowiki.Student$$FastClassBySpringCGLIB$$7dc55815.invoke(<generated>)
   at org.springframework.cglib.proxy.MethodProxy.invoke(MethodProxy.java:204)
   at org.springframework.aop.framework.CglibAopProxy$CglibMethodInvocation.invokeJoinpoint(CglibAopProxy.java:717)
   at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:157)
   at org.springframework.aop.aspectj.AspectJAfterThrowingAdvice.invoke(AspectJAfterThrowingAdvice.java:58)
   at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:179)
   at org.springframework.aop.interceptor.ExposeInvocationInterceptor.invoke(ExposeInvocationInterceptor.java:92)
   at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:179)
   at org.springframework.aop.framework.CglibAopProxy$DynamicAdvisedInterceptor.intercept(CglibAopProxy.java:653)
   at com.iowiki.Student$$EnhancerBySpringCGLIB$$99b0a988.printThrowException(<generated>)
   at com.iowiki.MainApp.main(MainApp.java:13)