Springaop 简明教程

Spring AOP - XML Based After Throwing Advice

After-throwing 是一种建议类型，它确保仅在方法通过抛出异常退出时，建议才会在方法执行之后运行。以下是 after-throwing 建议的语法。

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>

其中，

  1. PointCut-id - 切点的 ID

  2. ex − 要抛出的异常。

  3. methodName − 函数的方法名称，在被调用的函数抛出异常并退出时被调用。

为了理解与 After Throwing Advice 相关的上述概念，让我们编写一个将实现 After Throwing Advice 的示例。为了用很少的建议编写示例，让我们使用现有的 Eclipse IDE，并按照以下步骤创建一个 Spring 应用程序 −

Step

Description

1

更新在章节 Spring AOP - Application 创建的学生项目。

2

更新 bean 配置并按如下说明运行应用程序。

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.tutorialspoint;

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.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 。

<?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.tutorialspoint.*.*(..))"/>
         <aop:after-throwing pointcut-ref = "selectAll"
            throwing = "ex" method = "afterThrowingAdvice"/>
      </aop:aspect>
   </aop:config>

   <!-- Definition for student bean -->
   <bean id = "student" class = "com.tutorialspoint.Student">
      <property name = "name"  value = "Zara" />
      <property name = "age"  value = "11"/>
   </bean>

   <!-- Definition for logging aspect -->
   <bean id = "logging" class = "com.tutorialspoint.Logging"/>
</beans>

Run Project

创建源和配置文件后，运行您的应用程序。在应用程序中右键单击 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.tutorialspoint.Student.printThrowException(Student.java:25)
...