In this article, we will discuss how to create three-layered architecture in typical Spring boot MVC projects.

Spring Boot makes it easy to create stand-alone, production-grade Spring based Applications that you can "just run".

Three-tier (or three-layer) architecture is a widely accepted solution to organize the codebase. According to this architecture, the codebase is divided into three separate layers with distinctive responsibilities.

Three Tier (Three Layer) Architecture

Spring Boot follows a layered architecture in which each layer communicates with the layer directly below or above (hierarchical structure) it:

Presentation layer: This is the user interface of the application that presents the application’s features and data to the user.

Business logic (or Application) layer: This layer contains the business logic that drives the application’s core functionalities. Like making decisions, calculations, evaluations, and processing the data passing between the other two layers.

Data access layer (or Data) layer: This layer is responsible for interacting with databases to save and retrieve application data.

Spring Boot Flow Architecture ( Example)

The below diagram shows the typical application flow of our Spring boot MVC web application with Thymeleaf:

1. Spring MVC controller receives an HTTP request from the client ( browser).
2. Spring MVC controller process the request and sends that request to the service layer.
3. Service Layer responsible to hold the business logic of the application.
4. Repository layer responsible for interacting with databases to save and retrieve application data.
5. Spring MVC controller return view ( JSP or Thymeleaf) to render on the browser.

How to use Three-layer architecture in Spring Boot MVC web applications.

In a Spring boot MVC web application, the three layers of the architecture will manifest as follows:

• Controller classes as the presentation layer. Keep this layer as thin as possible and limited to the mechanics of the MVC operations, e.g., receiving and validating the inputs, manipulating the model object, returning the appropriate ModelAndView object, and so on. All the business-related operations should be done in the service classes. Controller classes are usually put in a controller package.



• Service classes as the business logic layer. Calculations, data transformations, data processes, and cross-record validations (business rules) are usually done at this layer. They get called by the controller classes and might call repositories or other services. Service classes are usually put in a service package.



• Repository classes as data access layer. This layer’s responsibility is limited to Create, Retrieve, Update, and Delete (CRUD) operations on a data source, which is usually a relational or non-relational database. Repository classes are usually put in a repository package.

Consider below Spring MVC web application using Spring boot and Thymeleaf. We have created a three-layer architecture and each layer is mapped to the corresponding package.
For example:

• Presentation Layer - controller package
• Business Logic Layer - service package
• Data Access Layer - repository package

Conclusion

In this article, we have discussed how to create three-layered architecture in typical spring boot projects.

Three-tier (or three-layer) architecture is a widely accepted solution to organize the codebase. According to this architecture, the codebase is divided into three separate layers with distinctive responsibilities.

Related Spring and Spring Boot Tutorials/Guides:

Spring Boot Tutorials [500+]s Spring Boot Testing Tutorial Spring Boot Microservice Tutorial Spring Boot Kafka Microservices Spring Boot + Apache Kafka Tutorial Spring Core Tutorial Spring MVC Tutorial Spring Data JPA Tutorial Spring Framework for Beginners Spring AOP Tutorial Spring Security Tutorial Spring Exceptions Tutorial Spring Boot Interview Questions Spring Boot Microservices Interview Questions Apache Kafka Tutorials Docker Tutorials and Guides Spring Boot RabbitMQ Tutorials Angular CRUD Example with Spring Boot Spring Boot + Angular 12 CRUD Full Stack Spring Boot + Angular 8 CRUD Full Stack Spring Boot + Angular 10 CRUD Full Stack React JS ( React Hooks) + Spring Boot Spring Boot + React JS CRUD Full Stack Spring Boot Thymeleaf CRUD Full Stack Spring Boot User Registration and Login Node Js + Express + MongoDB CRUDVue JS + Spring Boot REST API Tutorial