Spring AOP Advices - After throwing advice example - xml based configuration

In Spring, aspect-oriented programming (AOP) is a programming paradigm that aims to increase modularity by allowing the separation of cross-cutting concerns. AOP forms a basis for aspect-oriented software development.

In this page you will see an example for Spring AOP - After throwing advice. Spring After throwing advice will be executed after the every exception throw.

pom.xml file gives all required dependencies:

<project xmlns="http://maven.apache.org/POM/4.0.0"    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"    xsi:schemaLocation="http://maven.apache.org/POM/4.0.0     http://maven.apache.org/xsd/maven-4.0.0.xsd">    <modelVersion>4.0.0</modelVersion>    <groupId>SpringJavaBasedConfig</groupId>    <artifactId>SpringJavaBasedConfig</artifactId>    <version>0.0.1-SNAPSHOT</version>    <properties>        <spring.version>3.2.0.RELEASE</spring.version>    </properties>    <dependencies>        <dependency>            <groupId>org.springframework</groupId>            <artifactId>spring-core</artifactId>            <version>${spring.version}</version>        </dependency>        <dependency>            <groupId>org.springframework</groupId>            <artifactId>spring-context</artifactId>            <version>${spring.version}</version>        </dependency>        <dependency>            <groupId>cglib</groupId>            <artifactId>cglib</artifactId>            <version>3.1</version>        </dependency>    </dependencies></project>

My business logic service class: If you call testThrowException() method, it will throw an exception. We want to run after throwing advice method.

package com.java2novice.bean;public class MyBusinessService {    public void runMyBusinessLogic(){        System.out.println("************************************");        System.out.println("Running business logic...");        System.out.println("************************************");    }    public void testThrowException() {        throw new NullPointerException();    }}

Now create “After Throwing Advice”. Create a class which implements ThrowsAdvice interface. It will execute after occuring every exception throw.

package com.java2novice.aop;import org.springframework.aop.ThrowsAdvice;public class CatchThrowException implements ThrowsAdvice{    public void afterThrowing(NullPointerException e) throws Throwable {        System.out.println("Inside CatchThrowException.afterThrowing() method...");        System.out.println("Running after throwing exception...");    }}

Here is the xml based configuration file. Add bean entry for CatchThrowException class (after throwing advice class). Also create a proxy for MyBusinessService class. In this proxy configuration, you should add two properties called ‘target’ and ‘interceptorNames‘. ‘target’ defines in which bean you want to introduce advice. ‘interceptorNames’ defines that which advice class you want to introduce to the said target.

<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"    xsi:schemaLocation="http://www.springframework.org/schema/beans    http://www.springframework.org/schema/beans/spring-beans-3.0.xsd    http://www.springframework.org/schema/context     http://www.springframework.org/schema/context/spring-context-3.0.xsd">    <bean id="busService" class="com.java2novice.bean.MyBusinessService" />    <bean id="afterThrow" class="com.java2novice.aop.CatchThrowException" />    <bean id="busServiceProxy" class="org.springframework.aop.framework.ProxyFactoryBean" >        <property name="target" ref="busService" />        <property name="interceptorNames">            <list>                <value>afterThrow</value>            </list>        </property>    </bean></beans>

Here is the final demo class: Note that we are calling proxy bean object, not the business service bean directly.

package com.java2novice.test;import org.springframework.context.ConfigurableApplicationContext;import org.springframework.context.support.ClassPathXmlApplicationContext;import com.java2novice.bean.MyBusinessService;public class SpringDemo {    public static void main(String a[]){        String confFile = "applicationContext.xml";        ConfigurableApplicationContext context                                             = new ClassPathXmlApplicationContext(confFile);        MyBusinessService busServ = (MyBusinessService) context.getBean("busServiceProxy");        try{            busServ.testThrowException();        } catch(Exception ex){        }    }}

Output:

Inside CatchThrowException.afterThrowing() method...Running after throwing exception...