Spring Boot with Kotlin

Introduction

The book "Spring Boot with Kotlin" by Miloš Vasić was published in 2018 and became one of the first comprehensive guides to creating web applications in Kotlin using the Spring Boot framework. At that time, Kotlin was just beginning to gain popularity among Android developers, and its use in backend development was still relatively new. The book offers a practical approach: from setting up the environment to deploying a finished application in the cloud. It is aimed at readers already familiar with the basics of Kotlin and Java, and seeks to bridge the gap between language theory and real-world enterprise system development.

What the book is about

The book covers the full lifecycle of creating a web application with Spring Boot using Kotlin. The author guides the reader through all stages: project setup, working with databases, creating REST APIs, authentication, testing, and deployment. Special attention is paid to integrating Kotlin-specific features (data classes, null safety, extension functions) with classic Spring components (IoC, AOP, MVC). Each chapter contains practical code examples that can be run and modified immediately.

Who this book is for

The book is intended for developers who already have experience with Java and the Spring Framework but want to switch to Kotlin or use it in new projects. It will also be useful for those who know Kotlin at a basic level and want to see how to apply it in backend development. The book is not suitable for programming beginners — a solid understanding of OOP, SQL, and web technologies is assumed.

What the reader will learn

• How to set up a Spring Boot project with Kotlin and Gradle/Maven.
• Creating RESTful web services using Spring MVC and Kotlin.
• Working with databases via Spring Data JPA and Exposed (Kotlin ORM).
• Implementing authentication and authorization with Spring Security.
• Writing unit and integration tests with JUnit 5 and MockK.
• Containerizing the application with Docker and deploying to the cloud (Heroku, AWS).
• Using Kotlin coroutines for asynchronous programming.
• Creating a microservice architecture with Spring Cloud.

Strengths

One of the book's main strengths is its practical focus. The author does not overload with theory but immediately shows how to write working code. The examples are well-structured and accompanied by explanations. The chapter on testing deserves special mention: it covers not only standard approaches but also the specifics of testing Kotlin code (for example, using MockK instead of Mockito). The book also contains many tips on performance optimization and security, making it useful for real-world projects.

Another plus is the emphasis on modern tools: Docker, Gradle Kotlin DSL, Spring Boot Actuator. This allows the reader to immediately learn the best practices of 2018-2019. Although several years have passed since its release, the core concepts remain relevant, and changes in Spring Boot 2.x and Kotlin 1.3+ do not make the book obsolete — rather, it serves as an excellent foundation that can be supplemented with fresh articles.

Who it is recommended for

The book will be useful for Java developers who want to learn Kotlin in the context of Spring Boot, as well as Kotlin developers looking to transition from Android to backend development. It is also suitable for senior university students in technical fields who are already familiar with the basics of web development. If you plan to create microservices in Kotlin or maintain legacy projects migrating from Java to Kotlin, this book will be a good starting point.

Overall, "Spring Boot with Kotlin" is a high-quality practical guide that helps bridge the gap between learning a language and real-world development. Despite its age, the book retains its value thanks to its clear structure and abundance of examples. We recommend it to everyone,