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

Spring AOP - After Throwing Advice

After-throwing是一种通知类型，它确保在方法执行后运行通知，只有当方法通过抛出异常退出时才会运行。 以下是投掷后建议的语法。

语法 (Syntax)

<aop:config>
   <aop:aspect id = "log" ref = "logging">
      <aop:PointCut id = "PointCut-id" expression = "execution( expression )"/>    
      <aop:after-throwing PointCut-ref = "PointCut-id" throwing = "ex" 
         method = "methodName"/>
   </aop:aspect>
</aop:config>

Where,

• PointCut-id - PointCut-id 。

• ex - 被抛出的异常。

• methodName - 被调用函数抛出异常并退出时要调用的函数的方法名称。

为了理解上述与After Throwing Advice相关的概念，让我们编写一个实现After Throwing Advice的示例。 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;
public class Logging {
   /**
    * This is the method which I would like to execute
    * if there is an exception raised.
    */
   public void afterThrowingAdvice(IllegalArgumentException ex) {
      System.out.println("There has been an exception: " + ex.toString());   
   } 
}

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:config>
      <aop:aspect id = "log" ref = "logging">
         <aop:PointCut id = "selectAll" 
         expression = "execution(* com.iowiki.*.*(..))"/>
         <aop:after-throwing PointCut-ref = "selectAll" 
            throwing = "ex" method = "afterThrowingAdvice"/>         
      </aop:aspect>
   </aop:config>
   <!-- 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
There has been an 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$$EnhancerBySpringCGLIB$$8514cd8.printThrowException(<generated>)
   at com.iowiki.MainApp.main(MainApp.java:15)