Spring Boot: Building a Multi-Module Application with Gradle (Java)

What is multi module project in Spring boot

• Spring boot project with nested gradle projects with parent gradle configuration where you can manage all gradle build for the all child projects.
• Multi module project is built from parent gradle config which manages group of submodules.

Why we need multi-module project

• This can help developers to split the project into multiple modules which is easy to maintain.
• All sub projects share common build file.

Project Structure In Intellij IDEA

• Parent project Name: spring-examples
• Sub projects: entity-common, entity-modules, entity-service

Parent gradle config

1. Define plugins with version.

plugins {
    id 'io.spring.dependency-management' version '1.0.11.RELEASE'
    id 'org.springframework.boot' version '2.7.0' apply false
}

2. Dependency Management

User can declare, resolve and define dependencies required by projects. Please find more details here Dependency management in Gradle

allprojects {
    apply plugin: 'io.spring.dependency-management'
    group 'com.spring.example'
    version = getProjectVersion

    dependencyManagement {
        imports {
            mavenBom("org.springframework.boot:spring-boot-dependencies:${versions.springBoot}")
            mavenBom("org.springframework.cloud:spring-cloud-dependencies:${versions.springCloud}")
        }
        dependencies {
            dependency group: 'io.micrometer', name: 'micrometer-registry-prometheus', version: versions.micrometer
            dependency group: 'commons-logging', name: 'commons-logging', version: versions.commonLogging
        }
    }
}

How to use sub project in another sub project

For demo purpose, we will consume entity-models project in entity-service.Update project’s build.gradle file and module presented in following block.

dependencies {
    implementation(project(':entity-models'))
}

Now you will be able to consume all classes declared inside entity-models

Project Details

Please visit this GitHub repo to check for full example

GitHub - dhirajsable/spring-examples