Building a Simple Employee Management Application Using Micronaut - GeeksforGeeks (2024)

Last Updated : 23 Sep, 2024

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In this article, we will demonstrate how to create a simple RESTful Employee Management Application using Micronaut. This article will guide you through saving employee information in a database and handling HTTP requests using Micronaut’s powerful features. We will compare Micronaut with Spring Boot to highlight key differences and use cases.

What is Micronaut?

Micronaut is a JVM-based framework designed for developing lightweight, modular applications. Developed by Oracle Cloud Infrastructure (OCI), it simplifies the process of building microservices by offering faster startup times, reduced memory usage, and more efficient performance compared to other frameworks like Spring Boot.

Key Features of Micronaut:

  • Compile-Time Dependency Injection: Dependency injection happens at compile-time instead of runtime, leading to faster startup times and reduced memory consumption since no reflection is used.
  • Modular and Lightweight: Micronaut is highly modular, letting developers include only the necessary components, reducing the application’s memory footprint.
  • Cloud-Native Support: It supports cloud-native features such as service discovery and distributed configuration.
  • Serverless-Friendly: Micronaut’s fast startup times and minimal resource consumption make it ideal for serverless architectures.
  • Built-in Security: Micronaut includes built-in support for validation, authentication, and authorization.

Use Cases for Micronaut:

Micronaut shines in specific environments, and here are a few key scenarios where it excels:

  • Microservices Architecture: Due to its fast startup times, low memory consumption, and modular design, Micronaut is ideal for building and managing microservices.
  • Serverless Computing: Micronaut’s efficient memory usage and fast startup make it perfect for serverless applications where you need to reduce cold start latency.
  • Cloud-Native Applications: Micronaut simplifies the deployment of applications in cloud environments by providing built-in support for distributed configuration and cloud providers like AWS, Google Cloud, and Azure.

Implementation to Create an Employee Management System Using Micronaut

This example walks through building a simple Employee Management API that allows users to save employee details in a database.

Step 1: Create a Micronaut Project

Go to Micronaut Launch and create a Micronaut project. Download the ZIP file, extract it, and open it in IntelliJ IDEA or your preferred IDE.

Building a Simple Employee Management Application Using Micronaut - GeeksforGeeks (1)


Open Micronaut Project in Intellij IDEA IDE.

Building a Simple Employee Management Application Using Micronaut - GeeksforGeeks (2)


Step 2: Employee Domain Class

Java
// Domain package for the Employee entitypackage com.emp.domain// Import necessary annotations and JPA packagesimport groovy.transform.Canonicalimport groovy.transform.CompileStaticimport jakarta.persistence.Entityimport jakarta.persistence.GeneratedValueimport jakarta.persistence.GenerationTypeimport jakarta.persistence.Id// Mark this class as a JPA Entity@Entity@CompileStatic@Canonicalclass Employee { // Define the primary key for the Employee entity @Id @GeneratedValue(strategy = GenerationType.IDENTITY) Long id // Define other attributes of the Employee String name String email String city Long salary}


This domain class represents the Employee entity, which will be used to map the employee data to the database.

Step 3: Create Repository

Java
// Define repository package for Employeepackage com.emp.repositoryimport com.emp.domain.Employeeimport io.micronaut.data.annotation.Repositoryimport io.micronaut.data.jpa.repository.JpaRepositoryimport jakarta.inject.Singleton// Define a repository interface for Employee using Micronaut Data JPA@Singleton@Repositoryabstract class EmployeeRepository implements JpaRepository<Employee, Long> {}


The EmployeeRepository provides basic CRUD operations for the Employee entity by extending JpaRepository.

Step 4: Create DTO for Payload

Java
// Define a DTO for Employee data transferpackage com.emp.dto.requestimport groovy.transform.Canonicalimport groovy.transform.CompileStaticimport io.micronaut.core.annotation.Introspectedimport io.micronaut.serde.annotation.Serdeable@Introspected@CompileStatic@Canonical@Serdeable.Deserializableclass EmployeeDto { String name String email String city Long salary}


This DTO (Data Transfer Object) is used to receive the employee information from the client in the API request.

Step 5: Create Response DTO

Java
// Response class to send a result back to the clientpackage com.emp.dto.responseimport com.fasterxml.jackson.annotation.JsonIgnorePropertiesimport groovy.transform.Canonicalimport groovy.transform.CompileStaticimport io.micronaut.core.annotation.Introspected@Introspected@CompileStatic@Canonical@JsonIgnoreProperties(ignoreUnknown = true)class EmployeeResp { String name String email String city Long salary}


This DTO is used to send the employee data back as a response after saving the employee to the database.

Step 6: Service Class

Java
// Define the service to handle business logicpackage com.emp.serviceimport com.emp.domain.Employeeimport com.emp.dto.request.EmployeeDtoimport com.emp.dto.response.EmployeeRespimport com.emp.repository.EmployeeRepositoryimport groovy.transform.CompileStaticimport jakarta.inject.Singleton@Singleton@CompileStaticclass EmployeeService { private final EmployeeRepository employeeRepository // Constructor-based dependency injection EmployeeService(EmployeeRepository employeeRepository) { this.employeeRepository = employeeRepository } // Method to save an employee EmployeeResp saveEmployee(EmployeeDto employeeDto) { Employee employee = convertToDomain(employeeDto) employeeRepository.save(employee) // Save employee to DB return convertResponse(employee) } // Convert DTO to Domain entity private static Employee convertToDomain(EmployeeDto employeeDto) { new Employee( name: employeeDto?.name, email: employeeDto?.email, city: employeeDto?.city, salary: employeeDto?.salary ) } // Convert Domain entity to Response DTO private static EmployeeResp convertResponse(Employee employee) { new EmployeeResp( name: employee?.name, email: employee?.email, city: employee?.city, salary: employee?.salary ) }}


The service class handles the business logic, such as converting the DTO to an entity and saving it to the database.

Step 7: Create Controller

Java
// Define the controller for the APIpackage com.emp.controllerimport com.emp.dto.request.EmployeeDtoimport com.emp.dto.response.EmployeeRespimport com.emp.service.EmployeeServiceimport io.micronaut.http.annotation.Bodyimport io.micronaut.http.annotation.Controllerimport io.micronaut.http.annotation.Post@Controller("/api/employee/")class EmployeeController { private final EmployeeService employeeService // Constructor-based dependency injection EmployeeController(EmployeeService employeeService) { this.employeeService = employeeService } // Endpoint to save an employee @Post("save") EmployeeResp saveEmployee(@Body EmployeeDto employeeDto) { return employeeService.saveEmployee(employeeDto) }}


The EmployeeController class defines the API endpoint /api/employee/save to handle HTTP POST requests for saving employee details.

Step 8: Testing the API

Run the application and test the API using Postman. Use a POST request with the following URL:

http://localhost:8080/api/employee/save

Provide the employee details in JSON format in the request body and check the response.

Output:

Building a Simple Employee Management Application Using Micronaut - GeeksforGeeks (3)

Difference Between Micronaut And Spring Boot

Features

Micronaut (AOT Compilation)

Spring Boot(Runtime Reflection)

Startup Time

Faster, due to compile-time dependency injection

Slower, as it relies on runtime reflection

Memory Footprint

Smaller

Larger

Dependency Injection

Compile-time

Runtime reflection

Reactive Programming

Natively supported

Supported, but with more setup complexity

Configuration

Less verbose, simpler setup

Requires extensive annotations and configurations.

Performance

Highly optimized for microservices

Optimized but heavier due to runtime ops

Community

Smaller community

Larger community

Documentation

Well-written records

Outstanding record-keeping

In this article, we have created a simple employee management API using Micronaut with a detailed comparison of its features against Spring Boot. Micronaut’s fast startup times and low memory usage make it a great choice for microservices, serverless, and cloud-native applications.



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