Thursday, 15 November 2018

How to apply AroundAdvice using RegexpMethodPointcutAdvisor and BeanNameAutoProxyCreator

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Advanced Spring AOP: Around Advice with Regex

Welcome to this beginner-friendly guide! Today, we are exploring how to use Spring AOP to target specific methods across multiple classes using regular expressions. This is a powerful way to keep your code clean and organized.

What is BeanNameAutoProxyCreator?

In many Spring applications, you want to apply logic (advice) to many beans at once. Instead of creating a proxy for each bean manually, the BeanNameAutoProxyCreator does the work for you. You just tell it which bean names to look for!

Setting Up the Project

In this example, we have two main services:

EmployeeService: Manages employee data like name, age, and address.
CustomerService: Manages customer data like name, age, and address.

We also have our AroundAdvice class, which implements the MethodInterceptor interface. This class contains the logic that will run before and after our methods.

Configuring the Advisor with Regex

We use the RegexpMethodPointcutAdvisor to define exactly which methods should be intercepted. By using a pattern like .*age.*, we can tell Spring to only apply our advice to methods that have the word "age" in them, such as getEmployeeAge and getCustomerAge.

How the Magic Happens

In the XML configuration, we link everything together. The BeanNameAutoProxyCreator identifies classes ending in "Service", and the RegexpMethodPointcutAdvisor filters those classes for specific method names. When you run the app, you'll see the advice executing only for the age-related methods!

🎥 Recommended Tutorials from Ram N Java

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How to apply AroundAdvice using RegexpMethodPointcutAdvisor and BeanNameAutoProxyCreator

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.BeanNameAutoProxyCreator">

        <property name="beanNames">

            <list>

                <value>*Service</value>

            </list>

        </property>

        <property name="interceptorNames">

            <list>

                <value>employeeAdvisor</value>

            </list>

        </property>

    </bean>

</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 29, 2018 9:00:07 AM org.springframework.context.support.AbstractApplicationContext prepareRefresh

INFO: Refreshing org.springframework.context.support.ClassPathXmlApplicationContext@736e9adb: startup date [Mon Oct 29 09:00:07 IST 2018]; root of context hierarchy

Oct 29, 2018 9:00:08 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