Simple Java Gradle Plugin

Overview

This repository contains an example of a simple Java Gradle plugin. The purpose of this example is to demonstrate:

Creation of a Java Gradle plugin
Generation of dynamic Gradle tasks
Basic file operations
Usage of third-party dependencies (JSON Patch)

The main project is nothing more than a template file and a properties file. The environmentTemplate.json file contains some properties describing a typical development environment. The environments.properties file contains key-value properties for each environment that will be injected into the template by the plugin.

The plugin executes the following logic:

The plugin reads the key-value pairs in the environments.properties file
For every key found, it will generate and configure a Gradle task of type SimpleTask (defined by the plugin)
Each SimpleTask will take the environmentTemplate.json file and inject the appropriate properties (this is done via JSON Patch), and it will generate a new file with the newly injected properties:

Example:

Template file

{
  "environmentName": "N/A",
  "description": "N/A",
  "applicationName": "Sample Application"
}

Properties

dev=Contains the latest code. Developer's playground to test integration with other systems.

Generated file

{
  "environmentName" : "dev",
  "description" : "Contains the latest code. Developer's playground to test integration with other systems.",
  "applicationName" : "Sample Application"
}

Usage

List all tasks generated by the SimplePlugin:

$ gradle tasks --all

Dynamic Tasks (type: SimpleTask) tasks
--------------------------------------
generateAllEnvironmentFiles - Generates files for all environments.
generatedevfile - Generates a file for the dev environment
generatelocalfile - Generates a file for the local environment
generateprodfile - Generates a file for the prod environment
generatestagefile - Generates a file for the stage environment

Run one or multiple tasks:

$ gradle generatedevfile

> Task :buildSrc:compileJava UP-TO-DATE
> Task :buildSrc:compileGroovy NO-SOURCE
> Task :buildSrc:processResources NO-SOURCE
> Task :buildSrc:classes UP-TO-DATE
> Task :buildSrc:jar UP-TO-DATE
> Task :buildSrc:assemble UP-TO-DATE
> Task :buildSrc:compileTestJava NO-SOURCE
> Task :buildSrc:compileTestGroovy NO-SOURCE
> Task :buildSrc:processTestResources NO-SOURCE
> Task :buildSrc:testClasses UP-TO-DATE
> Task :buildSrc:test NO-SOURCE
> Task :buildSrc:check UP-TO-DATE
> Task :buildSrc:build UP-TO-DATE
> Task :generatedevfile

BUILD SUCCESSFUL in 1s
1 actionable task: 1 executed

Run all tasks via the master task (depends on all generated tasks)

$ gradle generateAllEnvironmentFiles

The output files of all dynamic tasks can be seen in the build/generated directory