Monday, 12 November 2018

Spring AOP AroundAdvice[applied to all methods of the class] Example | Spring Tutorial

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Understanding Spring AOP Around Advice

In this tutorial, we dive into Spring AOP (Aspect-Oriented Programming). Specifically, we explore how to use Around Advice to intercept all methods within a class. This is incredibly useful when you want to execute logic both before and after a method runs, such as for logging or performance monitoring.

1. What is Around Advice?

Around Advice is the most powerful type of advice in Spring AOP. It surrounds a method call. You have control over when the actual method executes and can even decide to skip it or return a different value.

2. Implementing MethodInterceptor

To create Around Advice, we implement the MethodInterceptor interface. In the example shown in the video, we provide an implementation for the invoke method, which contains the logic to be applied across our service methods.

3. Configuring the Proxy

To apply this advice to all methods of a class like EmployeeService, we use a ProxyFactoryBean in the Spring configuration. We set the "target" to our service bean and add our advice bean to the "interceptorNames" list.

4. Why Apply to All Methods?

Applying advice to every method in a class ensures consistent behavior. For instance, you can automatically log the start and end of every action in your EmployeeService without writing repetitive code in every single method.

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Spring AOP AroundAdvice[applied to all methods of the class] Example | 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>aroundAdvice</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.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 16, 2018 9:16:55 AM org.springframework.context.support.AbstractApplicationContext prepareRefresh

INFO: Refreshing org.springframework.context.support.ClassPathXmlApplicationContext@736e9adb: startup date [Tue Oct 16 09:16:55 IST 2018]; root of context hierarchy

Oct 16, 2018 9:16:55 AM org.springframework.beans.factory.xml.XmlBeanDefinitionReader loadBeanDefinitions

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

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

AroundAdvice applied before actual method = getEmployeeName

Get Employee Name

obj = Dave

AroundAdvice applied after actual method =  getEmployeeName

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

AroundAdvice applied before actual method = getEmployeeAge

Get Employee Age

obj = 28

AroundAdvice applied after actual method =  getEmployeeAge

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

AroundAdvice applied before actual method = getEmployeeAddress

Get Employee Address

obj = A111, East Street

AroundAdvice applied after actual method =  getEmployeeAddress