Get Your Hands Dirty on Clean Architecture: A Hands-on Guide to Creating Clean Web Applications with Code Examples in Java

Clean architecture becomes easier to evaluate when you can see how its boundaries work in an actual application. Tom Hombergs takes that hands-on approach here, using a Java web application for transferring money to explore how Hexagonal Architecture can help keep software maintainable as requirements and dependencies change.

The focus is practical: how to arrange the parts of an application, make dependencies point in the right direction, and test the result—without suggesting that one architectural style is the answer for every project.

From layered design to clearer boundaries

The book begins by examining familiar layered architecture and the difficulties it can create, including database-driven design and obstacles to parallel work. It then develops the ideas behind dependency inversion and Hexagonal Architecture, connecting architectural principles to code and package structure.

Follow a use case through the application

Using its recurring money-transfer example, the book explores domain models, business-rule validation, input and output models, and the implementation of use cases. It then turns to web and persistence adapters, showing how those components connect the application to external interfaces and stored data.

Testing, mapping, and assembly

Later chapters consider unit and integration testing, system tests, strategies for mapping between architectural boundaries, and ways to assemble an application with Java and Spring. The discussion also addresses enforcing boundaries and making conscious decisions about shortcuts and their technical debt.

For developers who want the “how,” not only the diagram

Java developers can work directly with the examples; readers who understand object-oriented code in another language may also follow the broader architectural discussion. Some experience building web applications will help readers get the most from the examples.

If you want to compare architectural choices against working application code, this guide offers a focused route from principles to implementation.