Creating a REST API using Spring Boot allows developers to build scalable and production-ready web services with minimal configuration. It simplifies RESTful service development by providing built-in support for HTTP methods, dependency injection, and auto-configuration.
- Offers embedded servers (Tomcat/Jetty) to run applications without external deployment
- Supports API testing using tools like Postman or Swagger UI
- Allows easy configuration via application.properties or application.yml
Why Spring Boot?
Spring Boot makes it easy to create production-ready apps:
- Built on top of Spring Framework
- Reduces boilerplate code with auto-configurations
- Quick setup for REST APIs
- Beginner-friendly
Steps to Implements a REST API in Spring Boot
Follow the below steps to create and run a REST API in Spring Boot.
Step 1: Create the Spring Boot Project
Using Spring Initializr (Recommended)
1. Open Spring Initializr in your browser.
2. Fill in the project details:
- Project: Maven
- Language: Java
- Spring Boot version: (latest stable, e.g., 3.1.x)
- Group: com. example
- Artifact: demo
- Name: demo
- Packaging: Jar
- Java version: 17+
3. Click Add Dependencies-> Select Spring Web.
4. Click Generate-> It will download a .zip file.
5. Extract the zip-> Open it in your IDE (IntelliJ / Eclipse / VS Code).
Step 2: Define the Employee Entity
Create a simple Employee class inside com.example.demo:
package com.example.demo;
// Employee entity class
public class Employee {
private Integer id;
private String firstName;
private String lastName;
private String email;
// Default constructor
public Employee() {}
// Parameterized constructor
public Employee(Integer id, String firstName, String lastName, String email) {
this.id = id;
this.firstName = firstName;
this.lastName = lastName;
this.email = email;
}
// Getters and Setters
public Integer getId() {
return id;
}
public void setId(Integer id) {
this.id = id;
}
public String getFirstName() {
return firstName;
}
public void setFirstName(String firstName) {
this.firstName = firstName;
}
public String getLastName() {
return lastName;
}
public void setLastName(String lastName) {
this.lastName = lastName;
}
public String getEmail() {
return email;
}
public void setEmail(String email) {
this.email = email;
}
@Override
public String toString() {
return "Employee [id=" + id + ", firstName=" + firstName +
", lastName=" + lastName + ", email=" + email + "]";
}
}
Step 3: Create a Storage Class
Create a class to hold a list of employees.
package com.example.demo;
import java.util.ArrayList;
import java.util.List;
// Storage class for employees
public class Employees {
private List<Employee> employeeList;
// Get the employee list (initialize if null)
public List<Employee> getEmployeeList() {
if (employeeList == null) {
employeeList = new ArrayList<>();
}
return employeeList;
}
public void setEmployeeList(List<Employee> employeeList) {
this.employeeList = employeeList;
}
}
Step 4: Create the DAO Class
The DAO class will handle adding and retrieving employees.
package com.example.demo;
import org.springframework.stereotype.Repository;
@Repository
public class EmployeeDAO {
private static Employees employees = new Employees();
static {
// Initialize with sample employees
employees.getEmployeeList()
.add(new Employee(1, "Prem", "Tiwari", "prem@gmail.com"));
employees.getEmployeeList()
.add(new Employee(2, "Vikash", "Kumar", "vikash@gmail.com"));
employees.getEmployeeList()
.add(new Employee(3, "Ritesh", "Ojha", "ritesh@gmail.com"));
}
// Retrieve all employees
public Employees getAllEmployees() {
return employees;
}
// Add an employee
public void addEmployee(Employee employee) {
employees.getEmployeeList().add(employee);
}
}
Step 5: Create the Controller
The controller contains the REST API endpoints.
package com.example.demo;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.http.ResponseEntity;
import org.springframework.web.bind.annotation.*;
import org.springframework.web.servlet.support.ServletUriComponentsBuilder;
import java.net.URI;
// REST Controller for managing employees
@RestController
@RequestMapping("/employees")
public class EmployeeController {
@Autowired
private EmployeeDAO employeeDao;
// GET endpoint to fetch all employees
@GetMapping("/")
public Employees getEmployees() {
return employeeDao.getAllEmployees();
}
// POST endpoint to add a new employee
@PostMapping("/")
public ResponseEntity<Object>
addEmployee(@RequestBody Employee employee) {
// Generate ID for the new employee
Integer id = employeeDao.getAllEmployees()
.getEmployeeList().size() + 1;
employee.setId(id);
// Add employee to the list
employeeDao.addEmployee(employee);
// Build location URI for the new employee
URI location = ServletUriComponentsBuilder
.fromCurrentRequest()
.path("/{id}")
.buildAndExpand(employee.getId())
.toUri();
return ResponseEntity.created(location).build();
}
}
Step 6: Run the Application
Open DemoApplication.java (already generated by Spring Boot) and run it:
package com.example.demo;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
@SpringBootApplication
public class DemoApplication {
public static void main(String[] args) {
SpringApplication.run(DemoApplication.class, args);
}
}
Step 7: Testing the API
Now we can test the API using tools like Postman or a web browser.
GET Request: Fetch all employees
URL: http://localhost:8080/employees/
Response:
POST Request: Add a new employee
Response:
Again hitting the GET request after performing the POST request:
This concludes creating a REST API using Spring Boot. Now we have a fully functioning API to manage employees.