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Sadiul Hakim
Sadiul Hakim

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Maven Plugins

#java #maven #plugin

What is a Maven Plugin?

A Maven plugin is a set of goals that extend Maven’s functionality.
Think of Maven as the engine, and plugins as tools that tell Maven what to do — like compiling code, packaging a JAR, running tests, or deploying to a server.

Each plugin performs a specific task in the build lifecycle.

Example:

  • maven-compiler-plugin → compiles Java source files.
  • maven-surefire-plugin → runs unit tests.
  • maven-jar-plugin → packages compiled code into a JAR file.

How Plugins Work

A Maven build lifecycle (e.g., clean, default, site) consists of phases like compile, test, package, install, and deploy.

Each phase executes one or more plugin goals.

Example:

mvn package
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runs:

  • compile → via maven-compiler-plugin
  • test → via maven-surefire-plugin
  • package → via maven-jar-plugin (or maven-war-plugin)

Why Use Plugins?

Because Maven itself doesn’t "do" much — it delegates all real work to plugins.

They let you:

  • Automate build steps (compile, test, package)
  • Run code quality checks
  • Generate reports
  • Deploy artifacts to a repository
  • Create Docker images, run servers, etc.

Basically, plugins = automation + flexibility.

When to Use Plugins

Use a plugin when you need Maven to perform a custom or automated task that’s not built-in.
Examples:

Situation Plugin
Need to compile Java code maven-compiler-plugin
Need to create a JAR/WAR maven-jar-plugin / maven-war-plugin
Need to run unit tests maven-surefire-plugin
Need to run integration tests maven-failsafe-plugin
Need to execute custom Java class exec-maven-plugin
Need to package app as Docker image jib-maven-plugin or spotify-dockerfile-maven-plugin
Need to format code or lint spotless-maven-plugin, checkstyle-maven-plugin

Common Maven Plugins (with Use Cases)

Plugin Goal / Phase Purpose
maven-compiler-plugin compile, test-compile Compiles Java source code and test code.
maven-surefire-plugin test Runs unit tests.
maven-failsafe-plugin integration-test, verify Runs integration tests (after packaging).
maven-jar-plugin package Builds .jar files.
maven-war-plugin package Builds .war files for web apps.
maven-install-plugin install Installs the package into the local repository (~/.m2/repository).
maven-deploy-plugin deploy Deploys artifacts to remote repositories.
maven-clean-plugin clean Deletes target/ directory before a new build.
maven-site-plugin site Generates project documentation.
exec-maven-plugin Custom goals Runs Java main classes or external commands.
spring-boot-maven-plugin repackage Packages Spring Boot apps as executable JARs, allows mvn spring-boot:run.
checkstyle-maven-plugin verify Performs static code analysis using Checkstyle rules.
spotless-maven-plugin verify Formats and enforces code style.
jib-maven-plugin Custom goal Builds Docker/OCI images without Dockerfile.
liquibase-maven-plugin Custom goal Runs database migrations with Liquibase.

Example: Define a Plugin in pom.xml 

<build>
  <plugins>
    <plugin>
      <groupId>org.apache.maven.plugins</groupId>
      <artifactId>maven-compiler-plugin</artifactId>
      <version>3.11.0</version>
      <configuration>
        <source>21</source>
        <target>21</target>
      </configuration>
    </plugin>
  </plugins>
</build>
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Now running:

mvn compile
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will use Java 21 for compilation.

Summary

Concept Description
What Plugins extend Maven’s capabilities via goals.
How Bound to build phases (like compile/test/package).
Why Automate builds, testing, deployment, quality checks.
When Whenever a project step can be automated or repeated.

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