Creating JAR and WAR Files Using Gradle

Gradle is a powerful build automation tool widely used for Java applications. It allows developers to compile code, manage dependencies, run tests, and package applications into distributable formats such as JAR and WAR files.

What is a JAR File?

A JAR (Java ARchive) file is a compressed package that contains:

Compiled .class files
Resource files (properties, images, etc.)
A manifest file (MANIFEST.MF)

JAR files are commonly used for:

Standalone Java applications
Libraries and utilities
Microservices (e.g., Spring Boot JARs)

Creating a JAR File Using Gradle

1. Apply the Java Plugin

Gradle can generate a JAR automatically when the Java plugin is applied.

build.gradle

plugins {
    id 'java'
}

2. Project Structure

📁project-name

📁src

📁main

📁java

📄build.gradle

3. Build the JAR

Run the following command:

terminal

gradle build

The JAR file will be created at: build/libs/project-name.jar

4. Customizing the JAR (Optional)

build.gradle

jar {
    archiveBaseName = 'my-application'
    archiveVersion = '1.0.0'
    manifest {
        attributes(
            'Main-Class': 'com.example.MainClass'
        )
    }
}

What is a WAR File?

A WAR (Web Application ARchive) file is used to deploy Java web applications to servlet containers like:

Apache Tomcat

Jetty

WildFly

A WAR file contains:

Servlets and controllers
JSP files
HTML, CSS, JavaScript
WEB-INF configuration files

Creating a WAR File Using Gradle

1. Apply the WAR Plugin

build.gradle

plugins {
    id 'java'
    id 'war'
}

2. Project Structure

📁project-name

📁src

📁main

📁java

📁webapp

📄index.jsp

📁WEB-INF

📄web.xml

📄build.gradle

3. Build the WAR

Run:

terminal

gradle build

The WAR file will be generated at: build/libs/project-name.war

4. Customizing the WAR

build.gradle

war {
    archiveBaseName = 'my-web-app'
    archiveVersion = '1.0'
}

JAR vs WAR: Key Differences

JAR Files

Standalone Java applications
Contains compiled classes and resources
Can be executed directly with java -jar
Used for libraries and microservices

WAR Files

Web applications for servlet containers
Contains web resources (JSP, HTML, CSS)
Requires deployment to a server
Includes WEB-INF directory structure