🏁 Spring Boot Quickstart 🔥🔥🔥

Your first steps into the Spring ecosystem, creating the foundation of our Todo application. ⏱️ Time: 30 mins

🚀 What You’ll Build

A Todo project scaffolded with Spring Initializr
Your first Spring Boot app that says: Hello, Todo!
A working understanding of Spring Boot’s auto-configuration
A REST endpoint, served locally in your browser

📘 Key Concepts

Spring Boot project structure
@SpringBootApplication – the main entry point
@RestController – define simple APIs
application.properties – basic configuration

🧰 Prerequisites

Install the following:

✅ Java 17+

macOS:

brew install openjdk@17
export PATH="/opt/homebrew/opt/openjdk@17/bin:$PATH"

Ubuntu / Debian:

curl -s "https://get.sdkman.io" | bash
source "$HOME/.sdkman/bin/sdkman-init.sh"
sdk install java 17

Windows (PowerShell):
```
winget install -e --id Microsoft.OpenJDK.17
```
Restart your terminal so the new JDK is on your PATH.

✅ Maven

macOS:
```
brew install maven
```
Ubuntu / Debian:
```
sudo apt update
sudo apt install maven
```
Windows (PowerShell):
```
winget install -e --id Apache.Maven
```

✅ VS Code

Download: https://code.visualstudio.com
Extensions:
- Java Extension Pack ✅
- Spring Boot Extension Pack (optional)

🛠️ Hands-on: Build the Todo App

1️⃣ Create a Project (Spring Initializr)

macOS / Ubuntu / Windows: Both workflows below are identical across operating systems because Spring Initializr and VS Code provide the same UI everywhere.

📦 Option A: Inside VS Code

Open Command Palette:
- macOS: ⇧⌘P
- Windows/WSL: Ctrl+Shift+P
Run: Spring Initializr: Generate a Maven Project
Fill in:
- Language: Java
- Spring Boot Version: 3.2.x
- Group: com.example
- Artifact/Name: demo
- Package: com.example.demo
- Dependency: Spring Web
Choose folder → Open in VS Code

📦 Option B: start.spring.io

Same values as above
Download and unzip → Open in VS Code

2️⃣ Understand the Structure

macOS / Ubuntu / Windows: The generated project layout is identical on every platform.

demo/
├── src/main/java/com/example/demo/DemoApplication.java
├── src/main/resources/application.properties
└── pom.xml

DemoApplication.java – Main class
application.properties – Config
pom.xml – Maven dependencies

3️⃣ Add Your First Endpoint

macOS / Ubuntu / Windows: Create the controller class in the same package path; file navigation in VS Code or your editor is consistent across OSes.

Create TodoController.java:

package com.example.demo;

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

@RestController
public class TodoController {
    @GetMapping("/hello")
    public String hello() {
        return "Hello, Todo!";
    }
}

4️⃣ Run the App

🧑‍💻 VS Code Run Button

Open DemoApplication.java and press ▶️. Output should say Tomcat started on port 8080.

🍎 macOS / Linux Terminal

./mvnw spring-boot:run

🪟 Windows (PowerShell or CMD)

PowerShell:

./mvnw.cmd spring-boot:run

Command Prompt:

mvnw.cmd spring-boot:run

🐳 Run via Docker (sample project)

To run the already-created sample project (spring-zero-to-hero-codes) inside a container, make sure Docker Desktop is running, clone the repo, then from that project folder execute:

docker compose up --build

Code edits on your machine are reflected immediately in the container thanks to the bind mount. By default the container exposes http://localhost:8080/hello; if you change server.port, update the URL accordingly. Stop the container with docker compose down when finished.

5️⃣ Test in Your Browser

macOS / Ubuntu / Windows: Open a browser on your machine (Edge, Chrome, Safari, Firefox—your choice) and hit the URL; the response is the same on every OS.

Visit:

http://localhost:8080/hello

✅ You’ll see: Hello, Todo!

6️⃣ Configure Your App

macOS / Ubuntu / Windows: Edit application.properties using your editor; property locations are identical across platforms.

Edit src/main/resources/application.properties:

server.port=8080
spring.application.name=todo-app

Restart the app. Now visit:

http://localhost:8080/hello

Want to try a different port? Change server.port to 9090, restart, and hit http://localhost:9090/hello.

✅ Outcome

By now, you’ve:

Created a Spring Boot project
Built and tested your first REST API
Modified application settings