Maven Plugin

Maven plugins are used to extend Maven's core functionality and provide additional build features. This tutorial will guide you through the process of creating a custom Maven plugin and using it in a project.

1. Creating a Maven Plugin:

Create a new Maven project for the plugin with the following command:

mvn archetype:generate -DgroupId=com.example -DartifactId=my-maven-plugin -DarchetypeArtifactId=maven-archetype-mojo -DinteractiveMode=false

This command generates a plugin project with a basic structure and a sample Mojo (i.e., a Maven plugin's executable goal).

Navigate to the "my-maven-plugin" directory and examine the "pom.xml" file. It should include the "maven-plugin" packaging type and the "maven-plugin-plugin" configuration.

2. Implementing the Mojo:

Locate the sample Mojo file at "src/main/java/com/example/MyMojo.java". This file contains a skeleton implementation of a Mojo. Edit the file and replace the contents with the following code:

package com.example;

import org.apache.maven.plugin.AbstractMojo;
import org.apache.maven.plugin.MojoExecutionException;
import org.apache.maven.plugins.annotations.Mojo;

@Mojo(name = "say-hello")
public class MyMojo extends AbstractMojo {

    public void execute() throws MojoExecutionException {
        getLog().info("Hello, World!");
    }
}

This Mojo, named "say-hello," simply prints "Hello, World!" to the console when executed.

3. Building the Plugin:

Build the plugin project using the following command:

mvn clean install

This command compiles the plugin, packages it as a JAR, and installs it to the local Maven repository.

4. Using the Plugin in a Project:

Create a new Maven project or use an existing one. Open the project's "pom.xml" file and add the following plugin configuration inside the <plugins> element in the <build> section:

<plugin>
    <groupId>com.example</groupId>
    <artifactId>my-maven-plugin</artifactId>
    <version>1.0-SNAPSHOT</version>
    <executions>
        <execution>
            <goals>
                <goal>say-hello</goal>
            </goals>
        </execution>
    </executions>
</plugin>

This configuration adds the custom "my-maven-plugin" plugin and binds the "say-hello" goal to the default build lifecycle.

5. Running the Plugin:

Navigate to the project's directory and run the following command:

mvn compile

As the plugin is bound to the default build lifecycle, the "say-hello" goal is executed automatically, and you should see the "Hello, World!" message in the console output.

Alternatively, you can run the plugin directly using the following command:

mvn com.example:my-maven-plugin:1.0-SNAPSHOT:say-hello

This command explicitly calls the "say-hello" goal of the custom plugin.

In summary, this tutorial demonstrated how to create a custom Maven plugin, implement a Mojo, and use the plugin in a Maven project. This allows you to extend Maven's functionality and tailor the build process to your specific requirements.