maven lifecycle

Maven, a widely used build automation and project management tool, can seem a bit overwhelming at first glance. One of the key concepts you need to grasp to make the most of Maven is its build lifecycle. In this guide, we’ll delve deep into the Maven build lifecycle, breaking it down into its standard phases. Understanding these phases is essential for efficiently managing your projects and ensuring smooth and reliable builds.

What is the Maven Build Lifecycle?

In Maven, a build lifecycle is a well-defined series of phases that define the sequence in which different goals are executed. Each phase represents a specific step in the build process, and you can hook your own goals into these phases to customize the build according to your project’s needs.

Maven’s Standard Lifecycle Phases

1

Clean

This initial phase ensures a clean slate by removing any previously generated build artifacts. It’s a helpful step when you want to start fresh.

During the clean phase, Maven performs several critical actions:

• Deletes the target directory: This directory holds all the build output from previous runs, including compiled code, JARs, and other generated files. Removing it ensures you’re working with a clean project directory.

• Cleans up any resources generated during the previous build, such as temporary files or cached data.

• Prepares the project for a fresh build, erasing any remnants of previous builds.

Executing this phase:

Clean

mvn clean

Keep in mind that after running clean, you’ll need to rebuild your project using subsequent phases like validate, compile, and package.

2

Validate

Before diving into the build, Maven validates your project’s structure and configuration. This phase helps you catch early mistakes in your project setup.

During the validate phase, Maven performs various checks, including:

• Verifying that your project’s pom.xml file is valid and well-formed XML.

• Ensuring that the project’s dependencies are available and correctly specified.

• Validating any custom configuration or settings you’ve added to your project.

To run the validate phase:

Validate

mvn validate

3

Compile

In the compile phase, your source code is compiled into bytecode. This is where your Java code gets transformed into .class files, making it ready for further processing.

During compilation, Maven leverages the Java Compiler (javac) to translate your human-readable source code into bytecode that the Java Virtual Machine (JVM) can execute. This bytecode is then packaged into JAR files or other formats during later phases.

To run the compile phase:

Compile

mvn compile

4

Test

The test phase is where Maven runs your unit tests. These tests validate that your code behaves as expected, helping you catch bugs early in development. Maven uses testing frameworks like JUnit to execute these tests.

During this phase, Maven:

• Compiles your test source code and application source code (which was already compiled in the previous phase).

• Executes the tests, capturing and reporting test results.

• Stops the build if any tests fail, ensuring that your code meets the defined quality standards.

To run the test phase:

Test

mvn test

5

Package

After successful compilation and testing, Maven packages your code into a distributable format. The output could be a JAR, WAR, or any other format based on your project’s configuration. This phase creates the deployable artifact for your application.

Depending on your project type, the resulting artifact might be a standalone executable JAR, a web application archive (WAR), or a different format tailored to your project’s needs.

To run the package phase:

Package

mvn package

6

Verify

In the verify phase, Maven checks that the package created in the previous phase meets quality criteria. This can include code quality checks, code coverage analysis, and more. Plugins like SonarQube or JaCoCo are often used for these checks.

During this phase, Maven typically performs the following verifications:

• Code quality checks using tools like SonarQube or Checkstyle.

• Code coverage analysis to determine how much of your codebase is covered by tests.

• Ensuring that your project adheres to defined quality standards and best practices.

To run the verify phase:

Verify

mvn verify

7

Install

Once your code has passed all previous phases, it’s time to install it locally. Maven places the built artifact into your local repository, making it available for other projects on your local machine. This allows you to use your project as a dependency in other projects.

The install phase is useful for creating a local repository of artifacts that can be reused in other Maven projects on the same machine. It ensures that your project’s built artifacts are easily accessible to other projects without needing to deploy them to a remote repository.

To run the install phase:

Install

mvn install

8

Deploy

Finally, if your project is ready for release, the deploy phase comes into play. This phase deploys the artifact to a remote repository, making it accessible to other developers and projects. Remote repositories could be internal company repositories or public repositories like Maven Central.

The deployment phase typically involves:

• Uploading your project’s artifacts to a remote repository.

• Making these artifacts available to other developers and projects.

• Ensuring that the artifacts are properly versioned and can be easily referenced by other projects as dependencies.

To run the deploy phase:

Deploy

mvn deploy

Conclusion

Maven may have a learning curve, but with practice and a solid understanding of its build lifecycle, you’ll find it to be a valuable tool for managing your Java projects. So go ahead, experiment with different phases, and take control of your project builds with Maven.

For more tips on Maven CLI, check out: https://spkcli.com/blog/20-essential-tips-for-proficiency-in-maven's-command-line-interface