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In this tutorial, we will learn how to use Spring AOP in the Spring boot application. We will implement an Aspect for logging execution of service, controller, and repository Spring components using Spring AOP.

Before using Spring AOP in the spring boot application, you should familiar with Spring AOP terminology at Spring AOP Tutorial with Example.

Spring AOP provides the way to dynamically add the cross-cutting concern before, after, or around the actual logic using simple pluggable configurations. It makes it easy to maintain code in the present and future as well.

Examples of cross-cutting concerns:

Logging
Security
Transaction management
Auditing,
Caching
Internationalization
Error detection and correction
Memory management
Performance monitoring
Synchronization

In this tutorial, we will implement an Aspect for logging execution of service, controller, and repository Spring components.

Quick Start

So before starting a complete step by step example, here is a snippet of LoggingAspect source code for quick reference:

springBeanPointcut() - Pointcut that matches all repositories, services, and Web REST endpoints.
applicationPackagePointcut() - Pointcut that matches all Spring beans in the application's main packages.
logAfterThrowing() - Advice that logs methods throwing exceptions.
logAround() - Advice that logs when a method is entered and exited.

package net.guides.springboot2.springboot2jpacrudexample.aspect;

import java.util.Arrays;

import org.aspectj.lang.JoinPoint;
import org.aspectj.lang.ProceedingJoinPoint;
import org.aspectj.lang.annotation.AfterThrowing;
import org.aspectj.lang.annotation.Around;
import org.aspectj.lang.annotation.Aspect;
import org.aspectj.lang.annotation.Pointcut;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.stereotype.Component;

/**
 * Aspect for logging execution of service and repository Spring components.
 * @author Ramesh Fadatare
 *
 */
@Aspect
@Component
public class LoggingAspect {

    private final Logger log = LoggerFactory.getLogger(this.getClass());

    /**
     * Pointcut that matches all repositories, services and Web REST endpoints.
     */
    @Pointcut("within(@org.springframework.stereotype.Repository *)" +
        " || within(@org.springframework.stereotype.Service *)" +
        " || within(@org.springframework.web.bind.annotation.RestController *)")
    public void springBeanPointcut() {
        // Method is empty as this is just a Pointcut, the implementations are in the advices.
    }

    /**
     * Pointcut that matches all Spring beans in the application's main packages.
     */
    @Pointcut("within(net.guides.springboot2.springboot2jpacrudexample..*)" +
        " || within(net.guides.springboot2.springboot2jpacrudexample.service..*)" +
        " || within(net.guides.springboot2.springboot2jpacrudexample.controller..*)")
    public void applicationPackagePointcut() {
        // Method is empty as this is just a Pointcut, the implementations are in the advices.
    }

    /**
     * Advice that logs methods throwing exceptions.
     *
     * @param joinPoint join point for advice
     * @param e exception
     */
    @AfterThrowing(pointcut = "applicationPackagePointcut() && springBeanPointcut()", throwing = "e")
    public void logAfterThrowing(JoinPoint joinPoint, Throwable e) {
        log.error("Exception in {}.{}() with cause = {}", joinPoint.getSignature().getDeclaringTypeName(),
            joinPoint.getSignature().getName(), e.getCause() != null ? e.getCause() : "NULL");
    }

    /**
     * Advice that logs when a method is entered and exited.
     *
     * @param joinPoint join point for advice
     * @return result
     * @throws Throwable throws IllegalArgumentException
     */
    @Around("applicationPackagePointcut() && springBeanPointcut()")
    public Object logAround(ProceedingJoinPoint joinPoint) throws Throwable {
        if (log.isDebugEnabled()) {
            log.debug("Enter: {}.{}() with argument[s] = {}", joinPoint.getSignature().getDeclaringTypeName(),
                joinPoint.getSignature().getName(), Arrays.toString(joinPoint.getArgs()));
        }
        try {
            Object result = joinPoint.proceed();
            if (log.isDebugEnabled()) {
                log.debug("Exit: {}.{}() with result = {}", joinPoint.getSignature().getDeclaringTypeName(),
                    joinPoint.getSignature().getName(), result);
            }
            return result;
        } catch (IllegalArgumentException e) {
            log.error("Illegal argument: {} in {}.{}()", Arrays.toString(joinPoint.getArgs()),
                joinPoint.getSignature().getDeclaringTypeName(), joinPoint.getSignature().getName());
            throw e;
        }
    }
}

Let's create a complete step-by-step CRUD spring boot application with Spring AOP.

Tools and Technologies Used

Spring Boot - 2.1.4 RELEASE
Spring Framework - 5.1.6 RELEASE
Spring Data JPA - 2.16 RELEASE
Hibernate - 5.3.9.Final
Thymeleaf - 3.0.11 RELEASE
Maven - 3.2+
IDE - Eclipse or Spring Tool Suite (STS)
H2 Database - 1.4.99

Development Steps

Creating a Spring Boot Application
Project Structure
Maven Dependencies - Pom.xml
Domain Layer
The Controller Layer
The Service Layer
The Repository Layer
The Logging Aspect
Exception Handling
Running the Application
Spring Rest Client
Conclusion

1. Creating a Spring Boot Application

There are many ways to create a Spring Boot application. You can refer to below articles to create a Spring Boot application.

>> Create Spring Boot Project With Spring Initializer
>> Create Spring Boot Project in Spring Tool Suite [STS]

Refer next step to create the project packaging structure.

2. Project Structure

Following is the package or project structure for your reference -

3. Maven Dependencies - Pom.xml

<?xml version="1.0" encoding="UTF-8"?>
<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/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>
    <groupId>net.guides.springboot2</groupId>
    <artifactId>springboot2-springaop-example</artifactId>
    <version>0.0.1-SNAPSHOT</version>
    <packaging>jar</packaging>
    <name>springboot2-springaop-example</name>
    <description>Demo project for Spring Boot</description>
    <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>2.1.4.RELEASE</version>
        <relativePath />
        <!-- lookup parent from repository -->
    </parent>
    <properties>
        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
        <project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding>
        <java.version>1.8</java.version>
    </properties>
    <dependencies>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-data-jpa</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-actuator</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-aop</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-devtools</artifactId>
            <scope>runtime</scope>
        </dependency>
        <dependency>
            <groupId>com.h2database</groupId>
            <artifactId>h2</artifactId>
            <scope>runtime</scope>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-test</artifactId>
            <scope>test</scope>
        </dependency>
    </dependencies>
    <build>
        <plugins>
            <plugin>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-maven-plugin</artifactId>
            </plugin>
        </plugins>
    </build>
</project>

4. Domain Layer

Let's create a simple Employee JPA entity class with the following code in it:

package net.guides.springboot2.springboot2jpacrudexample.model;

import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.GenerationType;
import javax.persistence.Id;
import javax.persistence.Table;

@Entity
@Table(name = "employees")
public class Employee {

    private long id;
    private String firstName;
    private String lastName;
    private String emailId;

    public Employee() {

    }

    public Employee(String firstName, String lastName, String emailId) {
        this.firstName = firstName;
        this.lastName = lastName;
        this.emailId = emailId;
    }

    @Id
    @GeneratedValue(strategy = GenerationType.AUTO)
    public long getId() {
        return id;
    }
    public void setId(long id) {
        this.id = id;
    }

    @Column(name = "first_name", nullable = false)
    public String getFirstName() {
        return firstName;
    }
    public void setFirstName(String firstName) {
        this.firstName = firstName;
    }

    @Column(name = "last_name", nullable = false)
    public String getLastName() {
        return lastName;
    }
    public void setLastName(String lastName) {
        this.lastName = lastName;
    }

    @Column(name = "email_address", nullable = false)
    public String getEmailId() {
        return emailId;
    }
    public void setEmailId(String emailId) {
        this.emailId = emailId;
    }

    @Override
    public String toString() {
        return "Employee [id=" + id + ", firstName=" + firstName + ", lastName=" + lastName + ", emailId=" + emailId +
            "]";
    }
}

5. The Controller Layer

Let's first create a Spring rest controller class and then we will add the logging aspect to it:

package net.guides.springboot2.springboot2jpacrudexample.controller;

import java.util.List;
import java.util.Map;

import javax.validation.Valid;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.http.ResponseEntity;
import org.springframework.web.bind.annotation.DeleteMapping;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.PathVariable;
import org.springframework.web.bind.annotation.PostMapping;
import org.springframework.web.bind.annotation.PutMapping;
import org.springframework.web.bind.annotation.RequestBody;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;

import net.guides.springboot2.springboot2jpacrudexample.exception.ResourceNotFoundException;
import net.guides.springboot2.springboot2jpacrudexample.model.Employee;
import net.guides.springboot2.springboot2jpacrudexample.service.EmployeeService;

@RestController
@RequestMapping("/api/v1")
public class EmployeeController {
    @Autowired
    private EmployeeService employeeService;

    @GetMapping("/employees")
    public List < Employee > getAllEmployees() {
        return employeeService.getAllEmployees();
    }

    @GetMapping("/employees/{id}")
    public ResponseEntity < Employee > getEmployeeById(@PathVariable(value = "id") Long employeeId)
    throws ResourceNotFoundException {
        Employee employee = employeeService.getEmployeeById(employeeId)
            .orElseThrow(() - > new ResourceNotFoundException("Employee not found for this id :: " + employeeId));
        return ResponseEntity.ok().body(employee);
    }

    @PostMapping("/employees")
    public Employee createEmployee(@Valid @RequestBody Employee employee) {
        return employeeService.createEmployee(employee);
    }

    @PutMapping("/employees/{id}")
    public ResponseEntity < Employee > updateEmployee(@PathVariable(value = "id") Long employeeId,
        @Valid @RequestBody Employee employeeDetails) throws ResourceNotFoundException {
        Employee updatedEmployee = employeeService.updateEmployee(employeeId, employeeDetails);
        return ResponseEntity.ok(updatedEmployee);
    }

    @DeleteMapping("/employees/{id}")
    public Map < String, Boolean > deleteEmployee(@PathVariable(value = "id") Long employeeId)
    throws ResourceNotFoundException {
        return employeeService.deleteEmployee(employeeId);
    }
}

6. The Service Layer

Let's first create EmployeeService class and then we will add the logging aspect to it:

package net.guides.springboot2.springboot2jpacrudexample.service;

import java.util.HashMap;
import java.util.List;
import java.util.Map;
import java.util.Optional;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;

import net.guides.springboot2.springboot2jpacrudexample.exception.ResourceNotFoundException;
import net.guides.springboot2.springboot2jpacrudexample.model.Employee;
import net.guides.springboot2.springboot2jpacrudexample.repository.EmployeeRepository;

/**
 * Employee Service
 * @author Ramesh
 *
 */
@Service
public class EmployeeService {
    @Autowired
    private EmployeeRepository employeeRepository;

    public List < Employee > getAllEmployees() {
        return employeeRepository.findAll();
    }

    public Optional < Employee > getEmployeeById(Long employeeId)
    throws ResourceNotFoundException {
        return employeeRepository.findById(employeeId);
    }

    public Employee createEmployee(Employee employee) {
        return employeeRepository.save(employee);
    }

    public Employee updateEmployee(Long employeeId,
        Employee employeeDetails) throws ResourceNotFoundException {
        Employee employee = employeeRepository.findById(employeeId)
            .orElseThrow(() - > new ResourceNotFoundException("Employee not found for this id :: " + employeeId));

        employee.setEmailId(employeeDetails.getEmailId());
        employee.setLastName(employeeDetails.getLastName());
        employee.setFirstName(employeeDetails.getFirstName());
        final Employee updatedEmployee = employeeRepository.save(employee);
        return updatedEmployee;
    }

    public Map < String, Boolean > deleteEmployee(Long employeeId)
    throws ResourceNotFoundException {
        Employee employee = employeeRepository.findById(employeeId)
            .orElseThrow(() - > new ResourceNotFoundException("Employee not found for this id :: " + employeeId));

        employeeRepository.delete(employee);
        Map < String, Boolean > response = new HashMap < > ();
        response.put("deleted", Boolean.TRUE);
        return response;
    }
}

7. The Repository Layer

Let's first create EmployeeRepository and then we will add the logging aspect to it:

package net.guides.springboot2.springboot2jpacrudexample.repository;

import org.springframework.data.jpa.repository.JpaRepository;
import org.springframework.stereotype.Repository;

import net.guides.springboot2.springboot2jpacrudexample.model.Employee;

@Repository
public interface EmployeeRepository extends JpaRepository < Employee, Long > {

}

8. The Logging Aspect

Now, let's create an Aspect for logging execution of service and repository Spring components. We will create 4 methods and here are the details:

springBeanPointcut() - Pointcut that matches all repositories, services, and Web REST endpoints.
applicationPackagePointcut() - Pointcut that matches all Spring beans in the application's main packages.
logAfterThrowing() - Advice that logs methods throwing exceptions.
logAround() - Advice that logs when a method is entered and exited.

package net.guides.springboot2.springboot2jpacrudexample.aspect;

import java.util.Arrays;

import org.aspectj.lang.JoinPoint;
import org.aspectj.lang.ProceedingJoinPoint;
import org.aspectj.lang.annotation.AfterThrowing;
import org.aspectj.lang.annotation.Around;
import org.aspectj.lang.annotation.Aspect;
import org.aspectj.lang.annotation.Pointcut;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.stereotype.Component;

/**
 * Aspect for logging execution of service and repository Spring components.
 * @author Ramesh Fadatare
 *
 */
@Aspect
@Component
public class LoggingAspect {

    private final Logger log = LoggerFactory.getLogger(this.getClass());

    /**
     * Pointcut that matches all repositories, services and Web REST endpoints.
     */
    @Pointcut("within(@org.springframework.stereotype.Repository *)" +
        " || within(@org.springframework.stereotype.Service *)" +
        " || within(@org.springframework.web.bind.annotation.RestController *)")
    public void springBeanPointcut() {
        // Method is empty as this is just a Pointcut, the implementations are in the advices.
    }

    /**
     * Pointcut that matches all Spring beans in the application's main packages.
     */
    @Pointcut("within(net.guides.springboot2.springboot2jpacrudexample..*)" +
        " || within(net.guides.springboot2.springboot2jpacrudexample.service..*)" +
        " || within(net.guides.springboot2.springboot2jpacrudexample.controller..*)")
    public void applicationPackagePointcut() {
        // Method is empty as this is just a Pointcut, the implementations are in the advices.
    }

    /**
     * Advice that logs methods throwing exceptions.
     *
     * @param joinPoint join point for advice
     * @param e exception
     */
    @AfterThrowing(pointcut = "applicationPackagePointcut() && springBeanPointcut()", throwing = "e")
    public void logAfterThrowing(JoinPoint joinPoint, Throwable e) {
        log.error("Exception in {}.{}() with cause = {}", joinPoint.getSignature().getDeclaringTypeName(),
            joinPoint.getSignature().getName(), e.getCause() != null ? e.getCause() : "NULL");
    }

    /**
     * Advice that logs when a method is entered and exited.
     *
     * @param joinPoint join point for advice
     * @return result
     * @throws Throwable throws IllegalArgumentException
     */
    @Around("applicationPackagePointcut() && springBeanPointcut()")
    public Object logAround(ProceedingJoinPoint joinPoint) throws Throwable {
        if (log.isDebugEnabled()) {
            log.debug("Enter: {}.{}() with argument[s] = {}", joinPoint.getSignature().getDeclaringTypeName(),
                joinPoint.getSignature().getName(), Arrays.toString(joinPoint.getArgs()));
        }
        try {
            Object result = joinPoint.proceed();
            if (log.isDebugEnabled()) {
                log.debug("Exit: {}.{}() with result = {}", joinPoint.getSignature().getDeclaringTypeName(),
                    joinPoint.getSignature().getName(), result);
            }
            return result;
        } catch (IllegalArgumentException e) {
            log.error("Illegal argument: {} in {}.{}()", Arrays.toString(joinPoint.getArgs()),
                joinPoint.getSignature().getDeclaringTypeName(), joinPoint.getSignature().getName());
            throw e;
        }
    }
}

Database and Logging Configuration

We are using the H2 database for a quick start-up and for logging to work, please add the following logging statements in the application.properties file:

logging.level.org.springframework.web=INFO
logging.level.org.hibernate=ERROR
logging.level.net.guides=DEBUG

9. Exception Handling

Spring Boot provides a good default implementation for exception handling for RESTful Services. Let’s quickly look at the default Exception Handling features provided by Spring Boot.

Resource Not Present

Here's what happens when you fire a request to not resource found: http://localhost:8080/some-dummy-url

{
  "timestamp": 1512713804164,
  "status": 404,
  "error": "Not Found",
  "message": "No message available",
  "path": "/some-dummy-url"
}

That's a cool error response. It contains all the details that are typically needed.

What happens when we throw an Exception?

Let’s see what Spring Boot does when an exception is thrown from a Resource. we can specify the Response Status for a specific exception along with the definition of the Exception with ‘@ResponseStatus’ annotation.

Let's create a ResourceNotFoundException.java class.

import org.springframework.http.HttpStatus;
import org.springframework.web.bind.annotation.ResponseStatus;

@ResponseStatus(value = HttpStatus.NOT_FOUND)
public class ResourceNotFoundException extends Exception{

    private static final long serialVersionUID = 1L;

    public ResourceNotFoundException(String message){
        super(message);
    }
}

Customizing Error Response Structure

Default error response provided by Spring Boot contains all the details that are typically needed.

However, you might want to create a framework independent response structure for your organization. In that case, you can define a specific error response structure.

Let’s define a simple error response bean.

import java.util.Date;

public class ErrorDetails {
 private Date timestamp;
 private String message;
 private String details;

 public ErrorDetails(Date timestamp, String message, String details) {
  super();
  this.timestamp = timestamp;
  this.message = message;
  this.details = details;
 }

 public Date getTimestamp() {
  return timestamp;
 }

 public String getMessage() {
  return message;
 }

 public String getDetails() {
  return details;
 }
}

To use ErrorDetails to return the error response, let’s create a GlobalExceptionHandler class annotated with @ControllerAdvice annotation. This class handles exception-specific and global exceptions in a single place.

import java.util.Date;

import org.springframework.http.HttpStatus;
import org.springframework.http.ResponseEntity;
import org.springframework.web.bind.annotation.ControllerAdvice;
import org.springframework.web.bind.annotation.ExceptionHandler;
import org.springframework.web.context.request.WebRequest;

@ControllerAdvice
public class GlobalExceptionHandler {
    @ExceptionHandler(ResourceNotFoundException.class)
    public ResponseEntity<?> resourceNotFoundException(ResourceNotFoundException ex, WebRequest request) {
         ErrorDetails errorDetails = new ErrorDetails(new Date(), ex.getMessage(), request.getDescription(false));
         return new ResponseEntity<>(errorDetails, HttpStatus.NOT_FOUND);
    }

    @ExceptionHandler(Exception.class)
    public ResponseEntity<?> globleExcpetionHandler(Exception ex, WebRequest request) {
        ErrorDetails errorDetails = new ErrorDetails(new Date(), ex.getMessage(), request.getDescription(false));
        return new ResponseEntity<>(errorDetails, HttpStatus.INTERNAL_SERVER_ERROR);
    }
}

10. Running the Application

Finally, let’s define the application’s entry point. Like most Spring Boot applications, we can do this with a plain old main() method:

package net.guides.springboot2.springboot2jpacrudexample;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.boot.web.client.RestTemplateBuilder;
import org.springframework.context.annotation.Bean;
import org.springframework.web.client.RestTemplate;

@SpringBootApplication
public class Application {

    @Bean
    public RestTemplate restTemplate(RestTemplateBuilder builder) {
        return builder.build();
    }

    public static void main(String[] args) {
        SpringApplication.run(Application.class, args);
    }
}

11. Spring Rest Client

Once the above spring application is up and running, let's test all Spring rest APIs and logging results with the below Spring rest-client:

package net.guides.springboot2.springboot2jpacrudexample;

import java.util.Arrays;
import java.util.HashMap;
import java.util.Map;

import org.springframework.http.HttpEntity;
import org.springframework.http.HttpHeaders;
import org.springframework.http.HttpMethod;
import org.springframework.http.MediaType;
import org.springframework.http.ResponseEntity;
import org.springframework.web.client.RestTemplate;

import net.guides.springboot2.springboot2jpacrudexample.model.Employee;

public class SpringRestClient {

    private static final String GET_EMPLOYEES_ENDPOINT_URL = "http://localhost:8080/api/v1/employees";
    private static final String GET_EMPLOYEE_ENDPOINT_URL = "http://localhost:8080/api/v1/employees/{id}";
    private static final String CREATE_EMPLOYEE_ENDPOINT_URL = "http://localhost:8080/api/v1/employees";
    private static final String UPDATE_EMPLOYEE_ENDPOINT_URL = "http://localhost:8080/api/v1/employees/{id}";
    private static final String DELETE_EMPLOYEE_ENDPOINT_URL = "http://localhost:8080/api/v1/employees/{id}";
    private static RestTemplate restTemplate = new RestTemplate();

    public static void main(String[] args) {
        SpringRestClient springRestClient = new SpringRestClient();

        // Step1: first create a new employee
        springRestClient.createEmployee();

        // Step 2: get new created employee from step1
        springRestClient.getEmployeeById();

        // Step3: get all employees
        springRestClient.getEmployees();

        // Step4: Update employee with id = 1
        springRestClient.updateEmployee();

        // Step5: Delete employee with id = 1
        springRestClient.deleteEmployee();
    }

    private void getEmployees() {

        HttpHeaders headers = new HttpHeaders();
        headers.setAccept(Arrays.asList(MediaType.APPLICATION_JSON));
        HttpEntity < String > entity = new HttpEntity < String > ("parameters", headers);

        ResponseEntity < String > result = restTemplate.exchange(GET_EMPLOYEES_ENDPOINT_URL, HttpMethod.GET, entity,
            String.class);

        System.out.println(result);
    }

    private void getEmployeeById() {

        Map < String, String > params = new HashMap < String, String > ();
        params.put("id", "1");

        RestTemplate restTemplate = new RestTemplate();
        Employee result = restTemplate.getForObject(GET_EMPLOYEE_ENDPOINT_URL, Employee.class, params);

        System.out.println(result);
    }

    private void createEmployee() {

        Employee newEmployee = new Employee("admin", "admin", "admin@gmail.com");

        RestTemplate restTemplate = new RestTemplate();
        Employee result = restTemplate.postForObject(CREATE_EMPLOYEE_ENDPOINT_URL, newEmployee, Employee.class);

        System.out.println(result);
    }

    private void updateEmployee() {
        Map < String, String > params = new HashMap < String, String > ();
        params.put("id", "1");
        Employee updatedEmployee = new Employee("admin123", "admin123", "admin123@gmail.com");
        RestTemplate restTemplate = new RestTemplate();
        restTemplate.put(UPDATE_EMPLOYEE_ENDPOINT_URL, updatedEmployee, params);
    }

    private void deleteEmployee() {
        Map < String, String > params = new HashMap < String, String > ();
        params.put("id", "1");
        RestTemplate restTemplate = new RestTemplate();
        restTemplate.delete(DELETE_EMPLOYEE_ENDPOINT_URL, params);
    }
}

Output:

The logging statements are printed in the console, the above screenshot is for your reference.

12. Conclusion

We have learned how to use Spring AOP in the Spring boot application. We also looked into the implementation of an Aspect for logging execution of service, controller, and repository Spring components using Spring AOP.

The source code of this tutorial is hosted on my GitHub repository at https://github.com/RameshMF/spring-boot-tutorial