Wednesday, 14 November 2018

Spring AOP Example – Advice, Pointcut, Advisor - NameMatchMethodPointcut | Spring Tutorial

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Spring AOP: Understanding Advice, Pointcuts, and Advisors

In this tutorial, we take a hands-on look at how to apply specific logic to certain methods in your application without cluttering your business logic. We focus on the NameMatchMethodPointcut to filter exactly where our advice runs.

1. What is a Pointcut?

Think of a Pointcut as a targeting system. It defines where in your code the extra logic (Advice) should be applied. Instead of applying logic to every method in a class, a pointcut helps you pick and choose specific methods.

2. Using NameMatchMethodPointcut

The NameMatchMethodPointcut class is perfect for beginners. It allows you to specify method names directly. For example, if you only want to intercept a method named getEmployeeName, you can simply tell the pointcut to look for that exact name.

3. Bringing it Together with an Advisor

An Advisor is a simple object that groups your Advice (the logic) and your Pointcut (the target) together. In our XML configuration, we link these components so that Spring knows exactly which logic to run for which method.

Why Use This Approach?

Granular Control: You decide exactly which methods are affected.
Separation of Concerns: Your main code stays clean of logging or security logic.
Flexibility: You can change which methods are intercepted just by editing your configuration file.

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Spring AOP Example – Advice, Pointcut, Advisor - NameMatchMethodPointcut | Spring Tutorial

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";

    }

}

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

    <bean id="employeeServiceProxy" class="org.springframework.aop.framework.ProxyFactoryBean">

        <property name="target" ref="employeeService"></property>

        <property name="interceptorNames">

            <list>

                <value>employeeAdvisor</value>

            </list>

        </property>

    </bean>

    <bean id="employeePointcut" 

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

        <property name="mappedName" value="getEmployeeAge" />

    </bean>

    <bean id="employeeAdvisor" 

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

        <property name="pointcut" ref="employeePointcut" />

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

    </bean>

</beans>

App.java

package com.ram.core;

import org.springframework.context.ApplicationContext;

import org.springframework.context.support.ClassPathXmlApplicationContext;

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("employeeServiceProxy", EmployeeService.class);

        employeeService.getEmployeeName();

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

        employeeService.getEmployeeAge();

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

        employeeService.getEmployeeAddress();

    }

}

Output

Oct 19, 2018 5:22:11 PM org.springframework.context.support.AbstractApplicationContext prepareRefresh

INFO: Refreshing org.springframework.context.support.ClassPathXmlApplicationContext@6ebc05a6: startup date [Fri Oct 19 17:22:11 IST 2018]; root of context hierarchy

Oct 19, 2018 5:22:11 PM 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