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REST APIs using Spring Boot

Spring Boot makes it super simple to create RESTful APIs quickly with minimal configuration. Let’s break it down step by step:

REST API

A REST API is a web service that follows REST principles and allows clients (like browsers or mobile apps) to perform operations (like GET, POST, PUT, DELETE) on resources via HTTP.

Why Spring Boot

Auto-configuration: Spring Boot reduces boilerplate setup.
Embedded server: Comes with Tomcat/Jetty, no need to deploy WAR files.
Production-ready: Has built-in monitoring and configuration support.

Basic Steps to Build a REST API

Create a Spring Boot project

Open IntelliJ IDEA.
Go to File → New → Project.
Select Spring Initializr.
Fill in:
- Group: com.example
- Artifact: restapi
Add dependencies:
- Spring Web
- (Optional) Spring Boot DevTools
Click Finish to generate your project.

Create a Model Class

Create a simple model class inside the model package:

package com.example.restapi.model;

public class Employee {

private Long id;

private String name;

private String role;

// Getters and Setters

}

Build the REST Controller

Create a controller class inside the controller package:

package com.example.restapi.controller;

import com.example.restapi.model.Employee;

import org.springframework.web.bind.annotation.*;

import java.util.ArrayList;

import java.util.List;

@RestController

@RequestMapping("/api/employees")

public class EmployeeController {

private List<Employee> employees = new ArrayList<>();

@GetMapping

public List<Employee> getAllEmployees() {

return employees;

}

@PostMapping

public Employee addEmployee(@RequestBody Employee employee) {

employees.add(employee);

return employee;

}

@RestController: Combines @Controller + @ResponseBody.
@GetMapping, @PostMapping: Map HTTP methods (GET, POST) to Java methods.
@RequestBody: Binds JSON payload from the request to a Java object.

Run the Application

Right-click the main RestapiApplication.java class.
Click Run ‘RestapiApplication.main()’.
Open your browser or use Postman:
- GET http://localhost:8080/api/employees
- POST http://localhost:8080/api/employees with JSON body like:
  
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  {
    "id": 1,
    "name": "Alice",
    "role": "Developer"
  }