Spring AOP XML Schema based Example

Spring AOP Example

Aspect Oriented Programming

Aspect Oriented Programming entails breaking down program logic into distinct parts called so-called concerns. The functions that span multiple points  of an application are called cross-cutting concerns and these cross-cutting concerns are conceptually separate from the application's business logic

Important Terms

Aspect-A module which has a set of APIs providing cross-cutting requirements.

Join point- This represents a point in your application where you can plug-in AOP aspect

Advice- This is the actual action to be taken either before or after the method execution.

Point cut - This is a set of one or more join points where an advice should be executed

Example

1. Create a class to define aspect module

package com.pretech;
 
public class Observer {
    /**
    * This method will execute before executing any method
    */
    public void beforeAdvice(){
    System.out.println("Creating employee object");
    }
    /**
    * This method will execute after executing any method
    */
    public void afterAdvice(){
    System.out.println("Employee object created.");
    }
}

2. Create a java entity class 

package com.pretech;
 
public class Employee {
    public Employee() {
        System.out.println("Employee constructor executed");
    }
 
    private String name;
    private String company;
 
    public void setName(String name) {
        this.name = name;
    }
 
    public String getName() {
        return name;
    }
 
    public String getCompany() {
        return company;
    }
 
    public void setCompany(String company) {
        this.company = company;
    }
 
}

 

3. Create Beans configuration file (SpringConfig.xml)

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
   xmlns:aop="http://www.springframework.org/schema/aop"
   xmlns="http://www.springframework.org/schema/beans"
   xsi:schemaLocation="http://www.springframework.org/schema/beans
http://www.springframework.org/schema/beans/spring-beans-3.0.xsd
http://www.springframework.org/schema/aop
http://www.springframework.org/schema/aop/spring-aop-3.0.xsd " >
 
    <aop:config>
 
        <aop:aspect   id="observ"    ref="observer" >
 
            <aop:pointcut   id="aopPointCutID"    expression="execution(* com.pretech.*.*(..))" />
 
            <aop:before  method="beforeAdvice"    pointcut-ref="aopPointCutID" />
 
            <aop:after  method="afterAdvice"          pointcut-ref="aopPointCutID" />
 
        </aop:aspect>
    </aop:config>
 
    <bean
       id="employee"
       class="com.pretech.Employee" >
 
        <property
           name="name"
           value="Raghavan" />
 
        <property
           name="company"
           value="wipro" />
    </bean>
 
    <bean   id="observer"     class="com.pretech.Observer" />
 
</beans>

 

4. Create a Test program (AOPTest.java)

package com.pretech;
 
import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;
 
public class AOPTest {
 
    public static void main(String[] args) {
        ApplicationContext context =
                new ClassPathXmlApplicationContext("SpringConfig.xml");
                Employee employee = (Employee) context.getBean("employee");
                employee.getName();
                employee.getCompany();
    }
 
}

5. Output

Employee constructor executed
Employee constructor executed
Creating employee object
Employee object created.
Creating employee object
Employee object created.

 

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Spring AOP Example