In this chapter, we will write actual AOP applications using Spring AOP Framework. Before you start writing your first example using Spring-WS framework, you have to make sure that you have set up your Spring AOP environment properly as explained in Spring Web Services – Environment Setup chapter.

Now, proceed to write a simple console-ased Spring AOP Application, which will demonstrate AOP concepts.

Create a Project

Step 1 − Open a command console, go the C:MVN directory and execute the following mvn command.

C:MVN>mvn archetype:generate -DgroupId=com.tutorialspoint 
-DartifactId=Student -DarchetypeArtifactId=maven-archetype-quickstart 
-DinteractiveMode=false

Maven will start processing and will create the complete Java application project structure.

[INFO] Scanning for projects...
[INFO]
[INFO] ------------------< org.apache.maven:standalone-pom >-------------------
[INFO] Building Maven Stub Project (No POM) 1
[INFO] --------------------------------[ pom ]---------------------------------
[INFO]
[INFO] >>> maven-archetype-plugin:3.2.0:generate (default-cli) > generate-sources @ standalone-pom >>>
[INFO]
[INFO] <<< maven-archetype-plugin:3.2.0:generate (default-cli) < generate-sources @ standalone-pom <<<
[INFO]
[INFO]
[INFO] --- maven-archetype-plugin:3.2.0:generate (default-cli) @ standalone-pom ---
[INFO] Generating project in Batch mode
[INFO] ----------------------------------------------------------------------------
[INFO] Using following parameters for creating project from Old (1.x) Archetype: maven-archetype-quickstart:1.0
[INFO] ----------------------------------------------------------------------------
[INFO] Parameter: basedir, Value: C:MVN
[INFO] Parameter: package, Value: com.tutorialspoint
[INFO] Parameter: groupId, Value: com.tutorialspoint
[INFO] Parameter: artifactId, Value: Student
[INFO] Parameter: packageName, Value: com.tutorialspoint
[INFO] Parameter: version, Value: 1.0-SNAPSHOT
[INFO] project created from Old (1.x) Archetype in dir: C:MVNStudent
[INFO] ------------------------------------------------------------------------
[INFO] BUILD SUCCESS
[INFO] ------------------------------------------------------------------------
[INFO] Total time:  13.388 s
[INFO] Finished at: 2021-12-27T20:18:26+05:30
[INFO] ------------------------------------------------------------------------

Step 2 − Go to C:/MVN directory. You”ll see a Java application project created, named student (as specified in artifactId). Update the POM.xml to include Spring-AOP dependencies. Add MainApp.java, Student.java, and Logging.java files.

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.tutorialspoint</groupId>
   <artifactId>Student</artifactId>
   <packaging>jar</packaging>
   <version>1.0-SNAPSHOT</version>
   <name>Student</name>
   <url>http://maven.apache.org</url>

   <properties>
      <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
      <maven.compiler.source>1.7</maven.compiler.source>
      <maven.compiler.target>1.7</maven.compiler.target>
   </properties>

   <dependencies>
      <dependency>
         <groupId>junit</groupId>
         <artifactId>junit</artifactId>
         <version>4.11</version>
         <scope>test</scope>
      </dependency>
      <dependency>
         <groupId>org.springframework</groupId>
         <artifactId>spring-aop</artifactId>
         <version>5.3.14</version>
      </dependency>
      <dependency>
         <groupId>org.springframework</groupId>
         <artifactId>spring-context</artifactId>
         <version>5.3.14</version>
      </dependency>
      <dependency>
         <groupId>org.aspectj</groupId>
         <artifactId>aspectjweaver</artifactId>
         <version>1.9.7</version>
      </dependency>
   </dependencies>
</project>

Following is the content of the Logging.java file.

package com.tutorialspoint;

public class Logging {
   /** 
      * This is the method which I would like to execute
      * before a selected method execution.
   */
   public void beforeAdvice() {
      System.out.println("Going to setup student profile.");
   }
   /** 
      * This is the method which I would like to execute
      * after a selected method execution.
   */
   public void afterAdvice() {
      System.out.println("Student profile has been setup.");
   }
   /** 
      * This is the method which I would like to execute
      * when any method returns.
   */
   public void afterReturningAdvice(Object retVal){
      System.out.println("Returning:" + retVal.toString() );
   }
   /**
      * This is the method which I would like to execute
      * if there is an exception raised.
   */
   public void AfterThrowingAdvice(IllegalArgumentException ex) {
      System.out.println("There has been an exception: " + ex.toString());   
   }
}

Following is the content of the Student.java file.

package com.tutorialspoint;

public class Student {
   private Integer age;
   private String name;

   public void setAge(Integer age) {
      this.age = age;
   }
   public Integer getAge() {
      System.out.println("Age : " + age );
      return age;
   }
   public void setName(String name) {
      this.name = name;
   }
   public String getName() {
      System.out.println("Name : " + name );
      return name;
   }
   public 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.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;

public class MainApp {
   public static void main(String[] args) {
      ApplicationContext context = new ClassPathXmlApplicationContext("Beans.xml");

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

Step 3 − Add the configuration file Beans.xml under src > main > resources folder.

<?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:config>
      <aop:aspect id = "log" ref = "logging">
         <aop:pointcut id = "selectAll" 
            expression = "execution(* com.tutorialspoint.*.*(..))"/>
         <aop:before pointcut-ref = "selectAll" method = "beforeAdvice"/>
         <aop:after pointcut-ref = "selectAll" method = "afterAdvice"/>
         <aop:after-returning pointcut-ref = "selectAll" 
            returning = "retVal"
            method = "afterReturningAdvice"/>
         <aop:after-throwing pointcut-ref = "selectAll" 
            throwing = "ex"
            method = "AfterThrowingAdvice"/>
      </aop:aspect>
   </aop:config>

   <!-- 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>

Step 4 − Open the command console, go the C:MVN directory and execute the following mvn command.

C:MVN>Student> mvn package

Maven will start processing and downloading the required libraries.

C:MVNStudent>mvn package
[INFO] Scanning for projects...
[INFO]
[INFO] ---------------------< com.tutorialspoint:Student >---------------------
[INFO] Building Student 1.0-SNAPSHOT
[INFO] --------------------------------[ jar ]---------------------------------
[INFO]
[INFO] --- maven-resources-plugin:2.6:resources (default-resources) @ Student ---
[INFO] Using ''UTF-8'' encoding to copy filtered resources.
[INFO] Copying 1 resource
[INFO]
[INFO] --- maven-compiler-plugin:3.1:compile (default-compile) @ Student ---
[INFO] Nothing to compile - all classes are up to date
[INFO]
[INFO] --- maven-resources-plugin:2.6:testResources (default-testResources) @ Student ---
[INFO] Using ''UTF-8'' encoding to copy filtered resources.
[INFO] skip non existing resourceDirectory C:MVNStudentsrctestresources
[INFO]
[INFO] --- maven-compiler-plugin:3.1:testCompile (default-testCompile) @ Student ---
[INFO] Nothing to compile - all classes are up to date
[INFO]
[INFO] --- maven-surefire-plugin:2.12.4:test (default-test) @ Student ---
[INFO] Surefire report directory: C:MVNStudenttargetsurefire-reports

-------------------------------------------------------
 T E S T S
-------------------------------------------------------
Running com.tutorialspoint.AppTest
Tests run: 1, Failures: 0, Errors: 0, Skipped: 0, Time elapsed: 0.093 sec

Results :

Tests run: 1, Failures: 0, Errors: 0, Skipped: 0

[INFO]
[INFO] --- maven-jar-plugin:2.4:jar (default-jar) @ Student ---
[INFO] ------------------------------------------------------------------------
[INFO] BUILD SUCCESS
[INFO] ------------------------------------------------------------------------
[INFO] Total time:  4.213 s
[INFO] Finished at: 2021-12-27T20:42:00+05:30
[INFO] ------------------------------------------------------------------------
C:MVNStudent>

Import Project in Eclipse

Step 1 − Open Eclipse.

Step 2 − Select File → Import → option.

Step 3 − Select Maven Projects Option. Click the Next Button.

Step 4 − Select Project location, where Student project was created using Maven.

Step 5 − Click Finish Button.

Run Project

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

Going to setup student profile.
Name : Zara
Student profile has been setup.
Returning:Zara
Going to setup student profile.
Age : 11
Student profile has been setup.
Returning:11
Going to setup student profile.
Exception raised
Student profile has been setup.
There has been an exception: java.lang.IllegalArgumentException
Exception in thread "main" java.lang.IllegalArgumentException
	at com.tutorialspoint.Student.printThrowException(Student.java:25)
...

Let us write an example which will implement advice using Annotation based configuration. For this, let us have a working Eclipse IDE in place and use the following steps to create a Spring application.

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

@Aspect
public 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.*.*(..))")
   private void selectAll(){}

   /** 
      * This is the method which I would like to execute
      * before a selected method execution.
   */
   @Before("selectAll()")
   public void beforeAdvice(){
      System.out.println("Going to setup student profile.");
   }  
}

Following is the content of the Student.java file.

package com.tutorialspoint;

public class Student {
   private Integer age;
   private String name;

   public void setAge(Integer age) {
      this.age = age;
   }
   public Integer getAge() {
      System.out.println("Age : " + age );
      return age;
   }
   public void setName(String name) {
      this.name = name;
   }
   public String getName() {
      System.out.println("Name : " + name );
      return name;
   }
   public 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.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;

public class MainApp {
   public static void main(String[] args) {
      ApplicationContext context = new ClassPathXmlApplicationContext("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 application. Rightclick on MainApp.java in your application and use run as Java Application command. If everything is fine with your application, it will print the following message.

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