Spring Boot Tutorial

Introduction to Spring Boot

Spring Boot is an extension of the Spring framework that simplifies the process of setting up and developing new Java applications. It helps developers create stand-alone, production-grade Spring-based applications with minimal effort.

With Spring Boot, you can get started quickly without needing to configure complex XML files. It provides a range of features such as auto-configuration, embedded servers, and a wide array of starter dependencies.

Getting Started with Spring Boot

Prerequisites

Before you begin, ensure you have the following installed:

• Java Development Kit (JDK) 8 or later
• Apache Maven or Gradle for dependency management
• An IDE (like IntelliJ IDEA, Eclipse, or Spring Tool Suite)

Creating a New Spring Boot Project

You can quickly create a Spring Boot project using Spring Initializr:

Select the project metadata (Group, Artifact, Name, etc.), choose Kotlin as the language, and add dependencies like Spring Web and Spring Data JPA. Click "Generate" to download a zip file containing your project.

Setting Up Your Application

Project Structure

Once you unzip your project, it should have a structure similar to this:

                my-spring-boot-app/
                ├── src/
                │   ├── main/
                │   │   ├── kotlin/
                │   │   │   └── com/
                │   │   │       └── example/
                │   │   │           └── myapp/
                │   │   │               └── MyApplication.kt
                │   │   └── resources/
                │   │       └── application.properties
                │   └── test/
                │       └── kotlin/
                └── pom.xml
                

Main Application Class

The main class is where your application starts. Here’s an example of a simple Spring Boot application in Kotlin:

                package com.example.myapp

                import org.springframework.boot.autoconfigure.SpringBootApplication
                import org.springframework.boot.runApplication

                @SpringBootApplication
                class MyApplication

                fun main(args: Array) {
                    runApplication(*args)
                }
                

Creating a RESTful API

Spring Boot makes it easy to create RESTful web services. Let’s create a simple REST controller.

                package com.example.myapp

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

                @RestController
                class HelloController {

                    @GetMapping("/hello")
                    fun greet(): String {
                        return "Hello, World!"
                    }
                }
                

This controller listens for GET requests at the "/hello" endpoint and responds with a greeting message.

Running Your Application

You can run your Spring Boot application using Maven or Gradle. Here’s how to do it with Maven:

After starting the application, you can access the REST endpoint by navigating to http://localhost:8080/hello in your web browser.

Conclusion

Spring Boot simplifies the process of building production-ready applications with minimal configuration. Its auto-configuration capabilities and built-in tools make it an excellent choice for developers looking to build modern web applications quickly.

In this tutorial, we covered the basics of Spring Boot, how to set up a new project, create a simple RESTful API, and run the application. From here, you can explore more advanced features such as database integration, security, and testing.