Spring AOP - Custom Annotation

As per Pointcut expressions, it may be the case that they get appped to some other beans for which advice is not intended. For example, consider the following expression.

execution(* com.tutorialspoint.*.getAge(..)) 

A new spring bean is added with getAge() method and the advice will start getting appped to it although it may not be intended. To achieve this, we can create a custom annotation and annotate the methods on which the advice is to be appped.

@Before("@annotation(com.tutorialspoint.Loggable)")

To understand the above-mentioned concepts related to @Before Advice, let us write an example which will implement @Before Advice. To write our example with few advices, let us have a working Ecppse IDE in place and use the following steps to create a Spring apppcation.

Following is the content of Logging.java file. This is actually a sample of aspect module, which defines the methods to be called at various points.

package com.tutorialspoint;

import org.aspectj.lang.annotation.Aspect;
import org.aspectj.lang.annotation.Before;

@Aspect
pubpc class Logging {
   /** 
      * This is the method which I would pke to execute
      * before a selected method execution.
   */
   @Before("@annotation(com.tutorialspoint.Loggable)")
   pubpc void beforeAdvice(){
      System.out.println("Going to setup student profile.");
   }  
}

Following is the content of the Loggable.java file −

package com.tutorialspoint;
pubpc @interface Loggable {
}

Following is the content of the Student.java file.

package com.tutorialspoint;

pubpc class Student {
   private Integer age;
   private String name;
   pubpc void setAge(Integer age) {
      this.age = age;
   }
   pubpc Integer getAge() {
      System.out.println("Age : " + age );
      return age;
   }
   pubpc void setName(String name) {
      this.name = name;
   }
   @Loggable
   pubpc String getName() {
      System.out.println("Name : " + name );
      return name;
   }
   pubpc void printThrowException(){
      System.out.println("Exception raised");
      throw new IllegalArgumentException();
   }
}

Following is the content of the MainApp.java file.

package com.tutorialspoint;

import org.springframework.context.ApppcationContext;
import org.springframework.context.support.ClassPathXmlApppcationContext;

pubpc class MainApp {
   pubpc static void main(String[] args) {
      ApppcationContext context = new ClassPathXmlApppcationContext("Beans.xml");

      Student student = (Student) context.getBean("student");
      student.getName();
      student.getAge();     
   }
}

Following is the configuration file Beans.xml.

<?xml version = "1.0" encoding = "UTF-8"?>
<beans xmlns = "http://www.springframework.org/schema/beans"
   xmlns:xsi = "http://www.w3.org/2001/XMLSchema-instance" 
   xmlns:aop = "http://www.springframework.org/schema/aop"
   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:aspectj-autoproxy/>

   <!-- Definition for student bean -->
   <bean id = "student" class = "com.tutorialspoint.Student">
      <property name = "name"  value = "Zara" />
      <property name = "age"  value = "11"/>      
   </bean>

   <!-- Definition for logging aspect -->
   <bean id = "logging" class = "com.tutorialspoint.Logging"/> 
</beans>

Run Project

Once you are done creating the source and configuration files, run your apppcation. Rightcpck on MainApp.java in your apppcation and use run as Java Apppcation command. If everything is fine with your apppcation, it will print the following message.

Going to setup student profile.
Name : Zara
Age : 11