Getting Started with Spring Boot 3 for .NET Developers

I have been working with .NET since 2008; however, I recently started working in a team that primarily uses Java as the standard back-end language. Transitioning from .NET to Java can be both exciting and challenging.

For this guide, you’ll need some basic knowledge of Java to get started.

Spring Boot 3, a popular framework for building Java applications, offers many similarities to .NET frameworks like ASP.NET Core. This guide will help you bridge the gap and take your first steps into the Spring Boot ecosystem.

Why Spring Boot 3?

Spring Boot 3 simplifies Java application development, just like ASP.NET Core does for .NET. Here’s why it might intrigue you:

1. Minimal Configuration: Opinionated defaults for rapid development.
2. Native Support: Build lightweight, native executables with GraalVM.
3. Wide Adoption: A mature ecosystem with robust libraries and tools.
4. Java 17+: Leverages modern Java features, much like how .NET embraces modern C#.

Step 1: Set Up Your Environment

Ensure you have the following:

• Java 17 or later: Spring Boot 3 requires it. Think of it as the .NET 6 equivalent.
• Maven or Gradle: Build tools similar to MSBuild.
• An IDE like IntelliJ IDEA (similar to Visual Studio).

Verify your Java installation by running:

java -version

Step 2: Create a New Spring Boot Project

Spring Boot projects are typically initialized through Spring Initializr (akin to the .NET CLI project templates).

Option 1: Using Spring Initializr

1. Visit Spring Initializr.
2. Select:
   • Project: Maven or Gradle (like choosing NuGet).
   • Language: Java.
   • Spring Boot Version: 3.x.x.
3. Add dependencies:
   • Spring Web: Equivalent to ASP.NET Core for building REST APIs.
   • Spring Data JPA: Similar to Entity Framework Core for database interactions.
   • Spring Boot DevTools: Like Hot Reload in Visual Studio.
4. Download and import the project into IntelliJ or Eclipse.

Option 2: Use Your IDE

Many IDEs support project initialization directly, similar to creating a new project in Visual Studio.

Step 3: Explore the Project Structure

Here’s how a typical Spring Boot project maps to a .NET Core project:

• src/main/java: Contains your controllers, services, and entities. Equivalent to the Controllers, Models, and Services folders in ASP.NET.
• src/main/resources: Configuration files like application.properties. Think of it like appsettings.json.
• pom.xml or build.gradle: Manages dependencies, similar to .csproj.

Step 4: Build Your First REST API

Create a simple REST API in Spring Boot:

package com.example.demo;

import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RestController;

@RestController
public class HelloController {
    @GetMapping("/hello")
    public String sayHello() {
        return "Hello from Spring Boot 3!";
    }
}

.NET Equivalent:

[ApiController]
[Route("[controller]")]
public class HelloController : ControllerBase
{
    [HttpGet("hello")]
    public IActionResult SayHello()
    {
        return Ok("Hello from ASP.NET Core!");
    }
}

Step 5: Run the Application

In Spring Boot, running the application is as simple as executing a command:

./mvnw spring-boot:run   # For Maven
./gradlew bootRun        # For Gradle

Navigate to http://localhost:8080/hello to see your API in action.

Step 6: Comparing Core Concepts

Here’s a quick comparison of familiar .NET Core concepts and their Spring Boot equivalents:

.NET Core Concept	Spring Boot Equivalent
ASP.NET Middleware	Spring Interceptors & Filters
Dependency Injection	Built-in DI Container
Entity Framework Core	Spring Data JPA
appsettings.json	application.properties or YAML
NuGet	Maven or Gradle

Step 7: Expand Your Application

• Database Integration: Use Spring Data JPA to connect to a database, much like using EF Core.
• Security: Add Spring Security for authentication and authorization, similar to ASP.NET Identity.
• Observability: Use Spring Actuator for health checks and metrics, similar to .NET HealthChecks.

Step 8: Debugging and Hot Reload

Spring Boot’s DevTools provides hot-reloading, akin to .NET’s Hot Reload feature. Add spring-boot-devtools as a dependency to your project.

References

• Spring Initializr: https://start.spring.io/
• Spring Boot Documentation: https://docs.spring.io/spring-boot/docs/current/reference/html/
• Java 17 Documentation: https://openjdk.org/projects/jdk/17/
• Spring Framework 6: https://spring.io/projects/spring-framework
• GraalVM Documentation: https://www.graalvm.org/
• ASP.NET Core Overview: https://learn.microsoft.com/en-us/aspnet/core/

Conclusion

For .NET developers, learning Spring Boot 3 is a natural transition. Many concepts like dependency injection, REST APIs, and ORM tools are similar, allowing you to quickly adapt and leverage the strengths of the Java ecosystem.

I will create a series of posts following this guide to demonstrate how to put all these concepts into action by building a REST API for a product catalog. Stay tuned!

If you have any questions, I am glad to help.

Happy coding!

Comments

[Kaustubh Joshi]

Hey, great entry point article for .NET developers who might need to do some coding in Java Spring Boot.
I am working on both .NET and Spring Boot for past 4 years now, and I can say that, although the "How we write" part of both are comparatively similar, but the "in-depth" concept of both frameworks are truly worlds apart.

I would love to see you also compare these concept while also comparing the "how they work in background" in the future articles you write.

Thank you!

[Bassem Hussein]

Hello Kaustubh,

Thank you for your comment. Yes, my goal is to write a series of posts that go in-depth step by step. Spring Boot is new for me, but I have been working with .NET for a long time. So, I thought it would be a good idea to share my Spring Boot learning journey from a .NET developer perspective.
So more posts to follow :)