Spring AOP - Annotation Based Before Advice

@Before is an advice type which ensures that an advice runs before the method execution. Following is the syntax of @Before advice.

Syntax

@Pointcut("execution(* com.tutorialspoint.Student.getName(..))")
private void selectGetName(){}

@Before("selectGetName()")
pubpc void beforeAdvice(){
   System.out.println("Going to setup student profile.");
} 

Where,

@Pointcut − Mark a function as a Pointcut

execution( expression ) − Expression covering methods on which advice is to be appped.

@Before − Mark a function as an advice to be executed before method(s) covered by Pointcut.

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

@Aspect
pubpc class Logging {

   /** Following is the definition for a Pointcut to select
      *  all the methods available. So advice will be called
      *  for all the methods.
   */
   @Pointcut("execution(* com.tutorialspoint.Student.getName(..))")
   private void selectGetName(){}
   /** 
      * This is the method which I would pke to execute
      * before a selected method execution.
   */
   @Before("selectGetName()")
   pubpc void beforeAdvice(){
      System.out.println("Going to setup student profile.");
   }  
}

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;
   }
   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

The above-defined @Pointcut uses an expression to select method getAge() defined in class(es) under the package com.tutorialspoint. @After advice uses the above-defined Pointcut as a parameter. Effectively afterAdvice() method will be called before every method covered by the above Pointcut.