Introduction to Spring Boot

Spring Boot is a framework designed to simplify the development of production-ready applications using the Spring framework. This guide covers the key concepts and steps for getting started with Spring Boot, including setting up a new project, understanding key features, and building a simple application.

Key Concepts of Spring Boot

• Convention over Configuration: Spring Boot follows the principle of convention over configuration to reduce the need for boilerplate code.
• Auto-Configuration: Spring Boot automatically configures Spring and third-party libraries whenever possible.
• Spring Boot Starters: A set of convenient dependency descriptors that you can include in your application.
• Spring Boot Actuator: Provides production-ready features to help monitor and manage your application.
• Spring Boot CLI: A command-line tool that you can use to quickly prototype with Spring.

Setting Up a New Project

Use Spring Initializr to quickly create a new Spring Boot project:

https://start.spring.io/

Select the following options:

• Project: Maven Project
• Language: Java
• Spring Boot: (select the latest stable version)
• Project Metadata: Group, Artifact, Name, Description, Package name
• Dependencies: Web, Spring Boot DevTools, Lombok

Click "Generate" to download the project archive. Extract the archive and open it in your favorite IDE.

Understanding the Project Structure

src/main/java/com/example/demo/
    DemoApplication.java       // Main application class
    controllers/               // Controller classes
    models/                    // Model classes
    repositories/              // Repository classes
    services/                  // Service classes
src/main/resources/
    application.properties     // Configuration file

Main Application Class

The main application class is annotated with @SpringBootApplication, which is a convenience annotation that adds @Configuration, @EnableAutoConfiguration, and @ComponentScan:

DemoApplication.java

// DemoApplication.java
package com.example.demo;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;

@SpringBootApplication
public class DemoApplication {
    public static void main(String[] args) {
        SpringApplication.run(DemoApplication.class, args);
    }
}

Creating a Simple Controller

Create a controller to handle HTTP requests:

HelloController.java

// HelloController.java
package com.example.demo.controllers;

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

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

Running the Application

Run the application using your IDE or by running the following command in the terminal:

./mvnw spring-boot:run

Access the application at http://localhost:8080/hello to see the "Hello, Spring Boot!" message.

Key Features of Spring Boot

• Auto-Configuration: Automatically configures Spring and third-party libraries based on the jar dependencies you have added.
• Spring Boot Starters: Provide a set of convenient dependency descriptors for different functionalities.
• Spring Boot Actuator: Adds several production-ready features to help monitor and manage your application.
• Spring Boot DevTools: Provides additional development-time features such as automatic restarts, live reload, and configurations for enhanced productivity.
• Spring Boot CLI: A command-line tool that helps you quickly prototype with Spring.

Key Points

Conclusion

Spring Boot simplifies the development of production-ready applications using the Spring framework. By following the key concepts and steps outlined in this guide, developers can quickly get started with Spring Boot and build powerful applications with minimal effort. Happy coding!