Building a RESTful API with Spring Boot: A Quick Start Guide

Building a RESTful API with Spring Boot: A Quick Start Guide

Are you looking to create robust, scalable APIs with minimal hassle? Spring Boot is your go-to framework for building production-ready applications with Java. In this article, I’ll walk you through creating a simple RESTful API using Spring Boot, perfect for developers who want to dive into modern backend development. Let’s get started!

Why Spring Boot?

Spring Boot simplifies the complexities of traditional Spring applications by offering:

• Auto-configuration: Reduces boilerplate code.
• Embedded servers: Run applications with built-in Tomcat or Jetty.
• Production-ready features: Monitoring, metrics, and health checks out of the box.
• Vibrant ecosystem: Seamless integration with databases, security, and more.

What We’ll Build

We’ll create a basic REST API for managing a list of books. It will support CRUD operations (Create, Read, Update, Delete) and use an in-memory database for simplicity.

Step 1: Set Up Your Project

1. Use Spring Initializr:
2. Import into Your IDE:

Step 2: Define the Entity

Create a Book entity to represent the data model.

java

package com.example.bookapi.model;

import jakarta.persistence.Entity;
import jakarta.persistence.Id;

@Entity
public class Book {
    @Id
    private Long id;
    private String title;
    private String author;
    private double price;

    // Default constructor
    public Book() {}

    // Parameterized constructor
    public Book(Long id, String title quasi, String author, double price) {
        this.id = id;
        this.title = title;
        this.author = author;
        this.price = price;
    }

    // Getters and setters
    public Long getId() { return id; }
    public void setId(Long id) { this.id = id; }
    public String getTitle() { return title; }
    public void setTitle(String title) { this.title = title; }
    public String getAuthor() { return author; }
    public void setAuthor(String author) { this.author = author; }
    public double getPrice() { return price; }
    public void setPrice(double price) { this.price = price; }
}        

Step 3: Create the Repository

Spring Data JPA makes database operations a breeze. Define a repository interface for the Book entity.

java

package com.example.bookapi.repository;

import com.example.bookapi.model.Book;
import org.springframework.data.jpa.repository.JpaRepository;

public interface BookRepository extends JpaRepository<Book, Long> {
}        

Step 4: Build the Controller

Create a REST controller to handle HTTP requests.

java

package com.example.bookapi.controller;

import com.example.bookapi.model.Book;
import com.example.bookapi.repository.BookRepository;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.http.ResponseEntity;
import org.springframework.web.bind.annotation.*;

import java.util.List;
import java.util.Optional;

@RestController
@RequestMapping("/api/books")
public class BookController {

    @Autowired
    private BookRepository bookRepository;

    // Get all books
    @GetMapping
    public List<Book> getAllBooks() {
        return bookRepository.findAll();
    }

    // Get a book by ID
    @GetMapping("/{id}")
    public ResponseEntity<Book> getBookById(@PathVariable Long id) {
        Optional<Book> book = bookRepository.findById(id);
        return book.map(ResponseEntity::ok)
                   .orElseGet(() -> ResponseEntity.notFound().build());
    }

    // Create a book
    @PostMapping
    public Book createBook(@RequestBody Book book) {
        return bookRepository.save(book);
    }

    // Update a book
    @PutMapping("/{id}")
    public ResponseEntity<Book> updateBook(@PathVariable Long id, @RequestBody Book bookDetails) {
        Optional<Book> book = bookRepository.findById(id);
        if (book.isPresent()) {
            Book updatedBook = book.get();
            updatedBook.setTitle(bookDetails.getTitle());
            updatedBook.setAuthor(bookDetails.getAuthor());
            updatedBook.setPrice(bookDetails.getPrice());
            bookRepository.save(updatedBook);
            return ResponseEntity.ok(updatedBook);
        }
        return ResponseEntity.notFound().build();
    }

    // Delete a book
    @DeleteMapping("/{id}")
    public ResponseEntity<Void> deleteBook(@PathVariable Long id) {
        if (bookRepository.existsById(id)) {
            bookRepository.deleteById(id);
            return ResponseEntity.ok().build();
        }
        return ResponseEntity.notFound().build();
    }
}        

Step 5: Configure Application Properties

Add the following to src/main/resources/application.properties to configure the H2 in-memory database:

properties

spring.datasource.url=jdbc:h2:mem:testdb
spring.datasource.driverClassName=org.h2.Driver
spring.datasource.username=sa
spring.datasource.password=
spring.jpa.database-platform=org.hibernate.dialect.H2Dialect
spring.h2.console.enabled=true        

The H2 console can be accessed at http://localhost:8080/h2-console for debugging.

Step 6: Run and Test the Application

1. Run the Application:
2. Test the API: Use tools like Postman or curl to test the endpoints:

Step 7: Enhance Your Application

To make your API production-ready, consider adding:

• Validation: Use @Valid and Hibernate Validator for input validation.
• Exception Handling: Implement @ControllerAdvice for consistent error responses.
• Security: Add Spring Security for authentication and authorization.
• Swagger/OpenAPI: Document your API using Springdoc OpenAPI.
• Testing: Write unit and integration tests with JUnit and MockMvc.

#SpringBoot #Java #RESTAPI #BackendDevelopment #Tech

Thank you

Ekanadhreddy