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📜  Spring AOP-投掷建议后基于注释

📅  最后修改于: 2020-11-11 05:23:21             🧑  作者: Mango

@AfterThrowing是一种建议类型，可确保如果该方法引发异常，则建议将运行。以下是@AfterThrowing建议的语法。

句法

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

哪里，

  • @AfterThrowing-将函数标记为要在PointCut覆盖的方法之前执行的建议，如果该方法引发异常。

  • PointCut-提供用于选择函数的表达式。

  • execution(expression) -涵盖将要应用建议的方法的表达式。

  • throwing-要返回的异常的名称。

为了理解与@AfterThrowing建议有关的上述概念，让我们写一个示例来实现@AfterThrowing建议。为了在没有任何建议的情况下编写示例，请让我们准备一个可以运行的Eclipse IDE，并使用以下步骤创建Spring应用程序。

Step Description
1 Update the project Student created under chapter Spring AOP – Application.
2 Update the bean configuration and run the application as explained below.

以下是Logging.java文件的内容。这实际上是Aspect模块的示例，它定义了要在各个点调用的方法。

package com.tutorialspoint;

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.tutorialspoint.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.tutorialspoint;

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.tutorialspoint;

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 。

运行项目

完成创建源文件和配置文件后，运行您的应用程序。右键单击应用程序中的MainApp.java，然后使用“以Java应用程序身份运行”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.tutorialspoint.Student.printThrowException()
Exception: java.lang.IllegalArgumentException
Exception in thread "main" java.lang.IllegalArgumentException
   
   at com.tutorialspoint.Student.printThrowException(Student.java:25)
   
   at com.tutorialspoint.Student$$FastClassBySpringCGLIB$$7dc55815.invoke()
   
   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.tutorialspoint.Student$$EnhancerBySpringCGLIB$$99b0a988.printThrowException()
   
   at com.tutorialspoint.MainApp.main(MainApp.java:13)