Friday, 16 November 2018

How to apply AroundAdvice using RegexpMethodPointcutAdvisor and DefaultAdvisorAutoProxyCreator

🚀 Love learning Java and Spring?

Support the channel by subscribing for more expert tutorials!

Mastering Spring AOP: Around Advice with Regex

In this tutorial, we dive deep into Spring AOP (Aspect Oriented Programming). You will learn how to target specific methods for advice using regular expressions and automate the proxy creation process.

1. The Core Components

To make this work, we use two powerful Spring classes:

RegexpMethodPointcutAdvisor: This allows us to define which methods should be "advised" based on a pattern (regular expression).
DefaultAdvisorAutoProxyCreator: This is the "magic" bean. If it finds any advisor that matches your beans, it automatically creates the necessary proxies so you don't have to do it manually.

2. Defining our Services

In the video, we look at two services: EmployeeService and CustomerService. Both have methods like getName, getAge, and getAddress. Our goal is to apply logic only to the "Age" methods.

3. Setting up the XML Configuration

Inside the Spring configuration file, we set the pattern in our advisor to look for the word "age". This ensures that whether it is getEmployeeAge or getCustomerAge, our AroundAdvice will trigger perfectly.

4. Seeing the Results

When the application runs, you’ll see that the Around Advice is executed for the age-related methods, while the name and address methods run normally without interference. This is the power of clean, automated AOP!

📺 Watch More from Ram N Java

Check out these related tutorials to sharpen your Spring skills:

Click here to watch on Youtube:
https://www.youtube.com/watch?v=_7u2oS95pD0&list=UUhwKlOVR041tngjerWxVccw

Click the below Image to Enlarge:

How to apply AroundAdvice using RegexpMethodPointcutAdvisor and DefaultAdvisorAutoProxyCreator

pom.xml

<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/maven-v4_0_0.xsd">

    <modelVersion>4.0.0</modelVersion>

    <groupId>com.ram.core</groupId>

    <artifactId>SpringDemo</artifactId>

    <packaging>jar</packaging>

    <version>1.0-SNAPSHOT</version>

    <name>SpringDemo</name>

    <url>http://maven.apache.org</url>

    <properties>

        <spring.version>5.0.5.RELEASE</spring.version>

    </properties>

    <dependencies>

        <dependency>

            <groupId>junit</groupId>

            <artifactId>junit</artifactId>

            <version>3.8.1</version>

            <scope>test</scope>

        </dependency>

        <!-- Spring 5 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>

    </dependencies>

</project>

EmployeeService.java

package com.ram.service;

public class EmployeeService

{

    public String getEmployeeName()

    {

        System.out.println("Get Employee Name");

        return "Dave";

    }

    public int getEmployeeAge()

    {

        System.out.println("Get Employee Age");

        return 28;

    }

    public String getEmployeeAddress()

    {

        System.out.println("Get Employee Address");

        return "A111, East Street";

    }

}

CustomerService.java

package com.ram.service;

public class CustomerService

{

    public String getCustomerName()

    {

        System.out.println("Get Customer Name");

        return "Peter";

    }

    public int getCustomerAge()

    {

        System.out.println("Get Customer Age");

        return 38;

    }

    public String getCustomerAddress()

    {

        System.out.println("Get Customer Address");

        return "B111, North Street";

    }

}

AroundAdvice.java

package com.ram.Advice;

import org.aopalliance.intercept.MethodInterceptor;

import org.aopalliance.intercept.MethodInvocation;

public class AroundAdvice implements MethodInterceptor

{

    public Object invoke(MethodInvocation mi) throws Throwable

    {

        Object obj;

        System.out.println("AroundAdvice applied before actual method = "

                + mi.getMethod().getName());

        obj = mi.proceed();

        System.out.println("obj = " + obj);

        System.out.println("AroundAdvice applied after actual method =  "

                + mi.getMethod().getName());

        return obj;

    }

}

applicationContext.xml

<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-4.3.xsd

    http://www.springframework.org/schema/context

    http://www.springframework.org/schema/context/spring-context-4.3.xsd">

    <bean id="employeeService" class="com.ram.service.EmployeeService"></bean>

    <bean id="customerService" class="com.ram.service.CustomerService"></bean>

    <bean id="aroundAdvice" class="com.ram.Advice.AroundAdvice"></bean>

    <bean id="employeeAdvisor"

        class="org.springframework.aop.support.RegexpMethodPointcutAdvisor">

        <property name="patterns">

            <list>

                <value>.*Age.*</value>

            </list>

        </property>

        <property name="advice" ref="aroundAdvice" />

    </bean>

    <bean class="org.springframework.aop.framework.autoproxy.DefaultAdvisorAutoProxyCreator" />

</beans>

App.java

package com.ram.core;

import org.springframework.context.ApplicationContext;

import org.springframework.context.support.ClassPathXmlApplicationContext;

import com.ram.service.CustomerService;

import com.ram.service.EmployeeService;

public class App

{

    public static void main(String[] args)

    {

        ApplicationContext context = new ClassPathXmlApplicationContext(

                "applicationContext.xml");

        System.out.println("---------------------------------------");

        EmployeeService employeeService = context

                .getBean("employeeService", EmployeeService.class);

        employeeService.getEmployeeName();

        System.out.println("----------------------------------------");

        employeeService.getEmployeeAge();

        System.out.println("----------------------------------------");

        employeeService.getEmployeeAddress();

        CustomerService customerService = context

                .getBean("customerService", CustomerService.class);

        System.out.println("----------------------------------------");

        customerService.getCustomerName();

        System.out.println("----------------------------------------");

        customerService.getCustomerAge();

        System.out.println("----------------------------------------");

        customerService.getCustomerAddress();

    }

}

Output

Oct 30, 2018 9:29:55 AM org.springframework.context.support.AbstractApplicationContext prepareRefresh

INFO: Refreshing org.springframework.context.support.ClassPathXmlApplicationContext@736e9adb: startup date [Tue Oct 30 09:29:55 IST 2018]; root of context hierarchy

Oct 30, 2018 9:29:55 AM org.springframework.beans.factory.xml.XmlBeanDefinitionReader loadBeanDefinitions

INFO: Loading XML bean definitions from class path resource [applicationContext.xml]

---------------------------------------

Get Employee Name

----------------------------------------

AroundAdvice applied before actual method = getEmployeeAge

Get Employee Age

obj = 28

AroundAdvice applied after actual method =  getEmployeeAge

----------------------------------------

Get Employee Address

----------------------------------------

Get Customer Name

----------------------------------------

AroundAdvice applied before actual method = getCustomerAge

Get Customer Age

obj = 38

AroundAdvice applied after actual method =  getCustomerAge

----------------------------------------

Get Customer Address