Gradle Plugins

Introduction

Plugins bundle tasks, defaults, and conventions. The java plugin compiles code; application adds run; java-library models shared APIs. This chapter maps the plugins you will use in JVM backends and points to publishing and quality plugins for real pipelines.

Prerequisites

• Gradle tasks
• Build script basics

How Plugins Apply

plugins {
    id 'java'
    id 'application'
}

Applying a plugin:

• Registers tasks (compileJava, test, jar, …)
• Adds dependency configurations (implementation, …)
• Sets default directory layout (src/main/java)

Versioned external plugins:

plugins {
    id 'org.springframework.boot' version '3.4.0'
    id 'java'
}

Core JVM Plugins

java

Standard Java library or app without a default main:

plugins {
    id 'java'
}

Key tasks: compileJava, test, jar.

application

Adds runnable distribution and run task:

plugins {
    id 'java'
    id 'application'
}
 
application {
    mainClass = 'com.example.App'
}

./gradlew run

Creates startup scripts under build/install/ with installDist.

java-library

For reusable modules—distinguishes api vs implementation:

plugins {
    id 'java-library'
}

Use in lib modules of a multi-project build; apps consume the library with implementation project(':lib').

Publishing: maven-publish

Publish to Maven Local or a remote repository:

./gradlew publishToMavenLocal

Artifacts land in ~/.m2/repository—consumable by Maven or Gradle.

Quality: JaCoCo (Test Coverage)

./gradlew test jacocoTestReport

Open build/reports/jacoco/test/html/index.html.

Fat JAR (Shadow Plugin) — Brief

Runnable “uber JAR” with dependencies inside:

./gradlew shadowJar
java -jar build/libs/my-app.jar

Spring Boot uses its own packaging plugin instead of Shadow.

Plugin vs Maven Plugin Mapping

Choosing Plugins for a New Project

Mini Example: Apply java-library in a Subproject

settings.gradle:

include 'api', 'app'

api/build.gradle:

plugins {
    id 'java-library'
}
 
dependencies {
    api 'com.google.code.gson:gson:2.11.0'
}

app/build.gradle:

plugins {
    id 'java'
    id 'application'
}
 
dependencies {
    implementation project(':api')
}
 
application {
    mainClass = 'com.example.Main'
}

FAQ

Where are plugin versions defined?

In the plugins { id ... version } block or pluginManagement in settings.gradle.

Plugin not found on portal?

Check spelling and gradlePluginPortal() in pluginManagement.

Difference between plugins and apply plugin:?

Old apply plugin: 'java' style—prefer the plugins { } block in new projects.

What comes next?

Testing with Gradle.