Launch Your First Spring Boot App: A Practical Guide for Beginners

Welcome back to the Spring Boot Mastery series! So far, we've explored the core concepts of Spring Boot, from understanding its features and benefits to diving into the basics like beans, dependency injection, and application context.

In this article, we’ll take a hands-on approach to creating your first Spring Boot application. Whether you're a beginner or just looking to solidify your foundation, this guide will walk you through generating a Spring Boot project using Spring Initializr, exploring the project structure, and running your very first RESTful application. Plus, we’ll dive deeper into the choice between Maven and Gradle, helping you decide which build tool is right for your project.

Before you begin, make sure you have the following installed:

1. Java Development Kit (JDK) – Ensure you have JDK 8 or later installed (for this tutorial I am using JDK 21). If not, you can follow these guides: Java for Windows, Java for Mac.

2. IDE: IntelliJ IDEA – This tutorial uses IntelliJ IDEA, but you can use any Java IDE of your choice. If you don't have IntelliJ installed, refer to this guide: IntelliJ Setup.

Once these are set up, you're ready to get started!

Getting Started with Spring Initializr

Spring Initializr is a web-based tool that allows you to quickly generate a Spring Boot project with the dependencies you need. You can find it at Spring Initializr.

Step 1: Open your browser and go to Spring Initializr.

On the home page, you’ll notice several options for setting up your Spring Boot project. One of the key options is the Build Tool, when setting up your Spring Boot project, you'll choose a build tool: Maven, Gradle, or Groovy.

These tools manage dependencies, build, and package your project. For this demo, we'll use Maven as it's simple and widely adopted in the Spring Boot community. We’ll briefly touch on Gradle later in the blog, so you can decide which tool best fits your needs.

Step 2: Fill in the project metadata:

• Project: Choose Maven (as we’re using Maven for this demo).

• Language: Java (default choice).

• Spring Boot version: Choose the latest stable version (the one without SNAPSHOT).

• Group: This is typically your company’s domain, e.g., com.example.

• Artifact: The name of your project, e.g., myfirstapp.

• Name: Your application name (this can be the same as the artifact).

• Packaging: Choose Jar (default choice).

• Java version: Choose the version of Java you're using (e.g., 21 for this tutorial).

Step 3: On the right side of the Spring Initializr page, you'll see the Add Dependencies option. Here, you can include the Spring Boot starters we’ve discussed earlier in this series. For now, select Spring Web as the only dependency. This will bring in all the necessary components for building web applications, including RESTful services.

Step 4: Click Generate to download the project ZIP file. Once the ZIP file is downloaded, extract it to your preferred directory.

Spring Initializr was designed to be both simple for beginners and powerful for advanced developers, making it versatile across skill levels.

Maven vs. Gradle: A Deep Dive

Now that we’ve extracted the ZIP file and before moving into the IDE, let’s take a step back. When setting up your Spring Boot project on Spring Initializr, you were asked to choose a build tool, and we selected Maven.

But what about Gradle? Let’s take a closer look at both Maven and Gradle, understand their key differences, and explore which build tool might suit your project best.

What is Maven?

Maven is a build automation tool primarily used for Java projects. It uses XML (pom.xml) to define project configurations, dependencies, and build lifecycle. The key features of Maven include:

• Convention over Configuration: Maven relies on standard conventions (for example, directory structure, default build lifecycle) to reduce configuration complexity.

• Dependency Management: Maven has a powerful dependency management system that automatically handles transitive dependencies, ensuring that your project includes all the necessary libraries.

• Wide Ecosystem: Maven is widely used and supported in the Java ecosystem, and most Java libraries are published in Maven Central, making dependency management seamless.

Here’s an example of a basic pom.xml file in Maven:

Maven's central repository holds over 70,000 libraries, meaning developers rarely need to manually download dependencies.

What is Gradle?

Gradle is another build automation tool but with a modern, flexible approach. Unlike Maven, Gradle uses a Groovy-based DSL (build.gradle) to define build scripts. Key features of Gradle include:

• Declarative and Imperative: Gradle is both declarative (you declare the dependencies and tasks) and imperative (you can write custom logic).

• Incremental Builds: Gradle uses caching and parallel execution to speed up builds, especially for large projects. It can also determine if a task has already been executed and skip it if it hasn’t changed.

• Multi-project Builds: Gradle excels at managing large projects with multiple modules or microservices, which can be built together or independently.

Here’s an example of a basic build.gradle file in Gradle:

One of Gradle's standout features is its ability to integrate seamlessly with other tools, like Jenkins, Docker, and even cloud services.

Maven vs. Gradle: Which Should You Choose?

When deciding between Maven and Gradle, consider the following:

Maven:

• Ease of Use: Maven’s XML configuration is simple and well-documented, ideal for beginners.

• Consistency: Follows a well-defined build lifecycle, favoring convention over configuration.

• Wider Adoption: Most Spring Boot projects use Maven, so it's easy to find resources and community support.

Gradle:

• Performance: Gradle is faster, especially for larger projects, due to its incremental build system.

• Flexibility: Offers greater customization, allowing for more complex build logic.

• Modern Tool: Preferred for large-scale projects, especially in microservices, where performance and flexibility matter.

Which One to Choose?

• Maven is ideal for beginners and projects that prioritize simplicity and convention.

• Gradle is better suited for large-scale, performance-sensitive applications where flexibility is important as it may take longer build time for small projects.

Gradle was designed to be a more modern alternative to Maven, blending the flexibility of scripting with the structure of a build tool.

Exploring the Project Structure

After extracting the ZIP file, let's take a look at the project structure:

• src/main/java: This is where your application code will reside. The main class, typically annotated with @SpringBootApplication, will be here.

• src/main/resources: This folder contains configuration files like application.properties (used for environment-specific settings like server port, database connections, etc.).

• pom.xml: This is the build configuration file. For Maven, it's pom.xml, and for Gradle, it’s build.gradle. This file lists the project’s dependencies.

• application.properties: You’ll configure properties for things like server ports and logging levels here. We’ll explore this more in future posts.

Here’s what the src/main/java folder might look like:

Spring Boot’s default project structure is designed to minimize the number of files needed to get your app running, thanks to automatic configuration.

Creating a Simple REST Controller

Now, let's create a simple REST API that responds with a message. In Spring Boot, we use the @RestController annotation to create RESTful endpoints.

Step 1: In the /src/main/java/com/example/myfirstapp folder, create a new class called HelloController.java.

Step 2: Add the following code to define a simple GET endpoint:

This class does the following:

• @RestController: Marks the class as a controller where every method returns a response body.

• @GetMapping("/hello"): Defines a GET endpoint at the /hello URL path.

The methods inside a @RestController can return any type of object, and Spring Boot automatically converts it into the appropriate HTTP response (e.g., JSON or XML).

Running Your Application

To run your application:

Step 1: Navigate to the MyFirstAppApplication.java file. This is the main class annotated with @SpringBootApplication.

Step 2: Run the application by right-clicking the MyFirstAppApplication.java file and selecting Run.

Once the application starts, open your browser and visit http://localhost:8080/hello. You should see the message "Hello, Spring Boot!".

Spring Boot’s "just run" philosophy means you can often get your app up and running in minutes, even if you're new to Spring.

Conclusion

In this blog, we’ve taken the first steps toward building your very own Spring Boot application. From setting up the project on Spring Initializr to exploring the project structure and running your first RESTful endpoint, you've gained the foundational knowledge needed to dive deeper into Spring Boot development.

Now that you've set up your Spring Boot application, it's time to dive deeper into the core features that make Spring Boot so powerful. In the upcoming blogs, we’ll explore Spring Boot annotations, which serve as the building blocks of your application, simplifying everything from configuration to endpoint creation. We’ll also look into mastering Spring Boot configurations, including how to manage environment-specific setups using profiles and externalized configuration.

Stay tuned as we continue to unlock the full potential of Spring Boot and guide you to building robust, production-ready applications and if you have any questions or thoughts on Spring Boot, feel free to share them in the comments below!!

So, go ahead — boot up with Spring Boot and code the way to success😀!

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