Spring Boot Tutorial for Beginners - Crash Course using Spring Boot 3

Introduction

This tutorial is designed to guide you through the essentials of Spring Boot, helping you build and deploy a REST API efficiently. Whether you are a beginner or looking to refine your skills, this step-by-step guide will cover key concepts, project setup, and deployment strategies. By the end, you'll have a solid foundation to create your own Spring Boot applications.

Step 1: Prerequisites and Setup

Before diving into Spring Boot, ensure you have the following prerequisites:

• Java Development Kit (JDK) version 11 or higher installed.
• Maven or Gradle for project management (Maven is preferred in this tutorial).
• An Integrated Development Environment (IDE) such as IntelliJ IDEA, Eclipse, or Visual Studio Code.

Setup Instructions

1. Install the JDK from the Oracle website or use OpenJDK.
2. Install Maven from the Apache Maven website.
3. Choose and install an IDE that you are comfortable with.

Step 2: Understanding Spring Framework and Spring Boot

Familiarize yourself with key concepts in Spring to understand the framework better:

• Beans: Objects managed by the Spring IoC container.
• Application Context: The central interface to the Spring IoC container.
• Inversion of Control (IoC): A design principle where control over object creation is transferred from the program to a framework.
• Dependency Injection (DI): A technique where an object receives its dependencies from an external source rather than creating them itself.

Step 3: Creating a New Spring Boot Project

Now that you have the prerequisites and understanding, create a new Spring Boot project.

Project Creation Steps

1. Go to Spring Initializr.
2. Select the following options:
   • Project: Maven Project
   • Language: Java
   • Spring Boot: Choose the latest version (e.g., 3.x.x).
   • Group: com.example
   • Artifact: demo
   • Dependencies: Add Spring Web and Spring Data JPA.
3. Click on "Generate" to download the project zip file.
4. Extract the zip file and open it in your IDE.

Step 4: Spring Core Concepts

Learn about the core concepts of Spring, which are vital for building applications.

Key Concepts

• IoC Container: Manages the instantiation and lifecycle of beans.
• Beans Configuration: Configure beans with annotations like @Component, @Service, and @Repository.
• ApplicationContext: Can be used to access beans and manage them.

Step 5: Building a REST API with Spring MVC

You will now create a simple REST API using Spring MVC.

REST API Creation Steps

1. Create a new class called UserController in the controller package.
2. Annotate the class with @RestController.
3. Add the following methods to handle HTTP requests:

@RestController
@RequestMapping("/api/users")
public class UserController {

    @GetMapping
    public List<User> getAllUsers() {
        // Logic to retrieve users
    }

    @PostMapping
    public User createUser(@RequestBody User user) {
        // Logic to create a new user
    }
}

Step 6: Working with Databases in Spring Boot

Integrate a database to persist data.

Database Integration Steps

1. Configure database properties in application.properties:

spring.datasource.url=jdbc:mysql://localhost:3306/demo
spring.datasource.username=root
spring.datasource.password=yourpassword
spring.jpa.hibernate.ddl-auto=update

2. Create a User entity class with JPA annotations.

@Entity
public class User {
    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private Long id;
    private String name;
    private String email;
}

Step 7: Spring Data JPA and Repositories

Utilize Spring Data JPA for data access.

Repository Creation Steps

1. Create a repository interface for the User entity:

public interface UserRepository extends JpaRepository<User, Long> {
}

2. Use the repository in your controller to access user data.

Step 8: Configuration and Profiles

Learn how to manage different configurations using profiles.

Configuration Tips

• Use application-dev.properties for development configurations.
• Use @Profile("dev") annotations to specify which beans should be loaded for a profile.

Step 9: Production-Ready Features

Enhance your application with production-ready features.

Actuator Setup

1. Add the Spring Actuator dependency in your pom.xml:

<dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-actuator</artifactId>
</dependency>

2. Configure actuator endpoints in application.properties.

Step 10: Preparing for Production Deployment

Prepare your application for a production environment.

Deployment Steps

1. Build your project with Maven:

mvn clean package

2. Choose a platform for deployment (e.g., Railway).
3. Follow the platform-specific instructions for deploying a Spring Boot application.

Conclusion

By following this tutorial, you have learned the essential steps to create a Spring Boot application and REST API. You have also gained insights into database integration, using Spring Data JPA, and preparing your application for production. Continue exploring and building more complex applications to further enhance your skills in Spring development.