Building REST APIs with Spring Boot 4.0

Practical and code-first learning for Java developers to build, test and deploy applications using Java 21

This book is 100% completeLast updated on 2026-05-25

What you've got here is a hands-on walkthrough of Spring Boot 4.0, where we'll build a single application from start to finish, using the command line and then packaging it as a JAR at the end. Each chapter adds one real capability, like a REST endpoint, a database, an error handler, a security layer or a test suite. Each chapter gets straight into the code, and you can run, modify and break it to see what happens.

There's even a dedicated troubleshooting chapter at the end that deals with the exact errors beginners actually encounter in practice, not just hypothetical ones.

This book is 100% completeLast updated on 2026-05-25

GitforGits | Asian Publishing House

There's even a dedicated troubleshooting chapter at the end that deals with the exact errors beginners actually encounter in practice, not just hypothetical ones.

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About the Book

Built on top of Spring Framework 7, Spring Boot 4.0 simplifies the process of building API far easy.

I'd describe this fast-paced book as the perfect practical tutor for Java developers who are curious to develop apps, and not just read about them. All chapters are working sets, where you write code, run it, break it deliberately, and fix it. There are no long theory sections, and no abstract architecture talk. It's all connected from the first command to the final deployable JAR.

It's all about one main thing, your first REST API, and it takes you through Spring Boot 4.0 with Java 21, including configuration management, Spring Data JPA, structured error handling, operational monitoring with Actuator, role-based security with Spring Security 7.0, three layers of automated testing, and executable JAR packaging. There's even a whole chapter just on troubleshooting, so you can get past those tricky spots that always seem to trip up beginners in the real projects.

This book doesn't aim to cover everything Spring Boot has to offer. Instead, it focuses on the essentials, and it does this in a way that's easy to understand. There's plenty of code to get your hands onto, plus tests to pass and explanations to help you get the most out of it. When you're done, you'll have a production-ready API that's fully secured and tested, and the confidence to take it further on your own.

Key Learnings

Create a fully functional REST API from scratch using Spring Boot 4.0.
Use Java 21 record classes to configure type-safe, validated application properties.
Use derived query methods to persist and query data with Spring Data JPA.
Manage multiple runtime environments using Spring Profiles and profile-specific properties.
Use Spring Boot Actuator and Micrometer to expose health metrics and info endpoints.
Use role-based HTTP authentication to secure REST endpoints.
Use test slices to test controllers, repositories and full-stack behaviour.
You can package a Spring Boot application as a self-contained, deployable executable JAR file.
You will diagnose and resolve common Spring Boot startup, configuration and security failures.

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GitforGits | Asian Publishing House

We are the engineer’s publisher, the coder’s mentor, and the content alchemist—meticulously turning dense tech into practical gold. With a growing library of 100+ titles, we don’t just develop technical books, rather we build roadmaps for professionals across Python, MySQL, DevOps, Rust, AI, Kotlin, Arduino, Golang and everything around the massive IT ecosystem. Every chapter, every script, every project is a tool in the hands of developers who want to get things done.

Where others summarize, we construct step-by-step learning blueprints, cutting through clutter, banning the fluff, and ensuring every paragraph delivers hands-on value. Our audience isn’t learning from scratch—they’re leveling up with purpose, and we stand by them with code-first content, consistent project workflows, and a zero-redundancy approach.

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