Build a Multiple Module Project with Gradle

Introduction
Model of example
Create MathLibrary project
Create MathWebApp project
Create GradleMain project
Build projects
Run MathWebApp

1. Introduction

This document is based on:

Eclipse 4.6 (NEON)

You are viewing the advanced Gradle. If you are a beginner Gradle. You should look at the documentation for beginners Gradle (Gradle Hello world) at:

Gradle Tutorial for Beginners

2. Model of example

This is the model example in this document.

The objective of the guidelines is:

How a module using other module in Gradle
Packing multiple Module using Gradle (output: jar, war).
Run Web App on Gradle Tomcat Plugin.

MathWebApp: is a WebApp project
MathLibrary: is a library Project, contains utility classes used by MathWebApp.

GradleMain: will pack two projects above, it is a main module. GradleMain will:

Packing MathLibary to a jar file
Packing MathWebApp to a file war.

3. Create MathLibrary project

File/New/Other...

Enter:

Project Name: MathLibrary

Project is created.

Create class MathUtils:

The MathUtils class has a method for caculating the sum of two numbers in the MathLibrary project and will be used in the MathWebApp project.

package org.o7planning.mathutils;

public class MathUtils {

  public static int sum(int a, int b) {
      return a + b;
  }

}

4. Create MathWebApp project

Similarly create MathWebApp project.

Open file pom.xml

MathWebApp is a web application that uses the MathLibrary project as a library. Therefore you need to declare MathWebApp dependent on MathLibrary.

MathWebApp/build.gradle

apply plugin: 'java'
apply plugin: 'eclipse'
apply plugin: 'war'  

apply plugin: 'com.bmuschko.tomcat'

repositories {
   jcenter()
}

dependencies {    

   testCompile 'junit:junit:4.12'
   
 
   providedCompile "javax.servlet:javax.servlet-api:3.1.0"      
   
   compile project(':MathLibrary')
}


dependencies {
   def tomcatVersion = '7.0.59'
   
   tomcat "org.apache.tomcat.embed:tomcat-embed-core:${tomcatVersion}",
          "org.apache.tomcat.embed:tomcat-embed-logging-juli:${tomcatVersion}",
          "org.apache.tomcat.embed:tomcat-embed-jasper:${tomcatVersion}"
}


buildscript {

   repositories {
       jcenter()
   }

   dependencies {
       classpath 'com.bmuschko:gradle-tomcat-plugin:2.2.2'
   }
}

Each time you change build.gradle you need to use the Gradle tool to refresh the project.

Create index.jsp file using MathUtils, class in project MathLibrary.

index.jsp

<html>
<body>
<h2>Hello World!</h2>

<%

int a = 100;
int b = 200;

int c = org.o7planning.mathutils.MathUtils.sum(a,b);

out.println("<h2>"+ c+"</h2>");

%>

</body>
</html>

5. Create GradleMain project

Similarly create GradleMain project.

GradleMain is a project that builds 2 projects MathLibrary and MathWebApp. You need to define these two projects in the settings.gradle.

GradleMain/settings.gradle

rootProject.name = 'GradleMain'


include   ':MathLibrary', ':MathWebApp'
project(':MathLibrary').projectDir = new File(settingsDir, '../MathLibrary')
project(':MathWebApp').projectDir = new File(settingsDir, '../MathWebApp')

And declare GradleMain depends on Math Library & MathWebApp.

GradleMain/build.gradle

apply plugin: 'java'
apply plugin: 'eclipse'

repositories {
    jcenter()
}

dependencies {   
 
    testCompile 'junit:junit:4.12'     
}

dependencies {
    compile project(':MathLibrary')
    compile project(':MathWebApp')
}

Each time you change build.gradle you need to use the Gradle tool to refresh the project.