Maven Lifecycle And Basic Maven Commands (2021)

Introduction

Maven is a widely used project object model-POM used in managing and building projects that are Java-based for Maven lifecycle management. This power-tool for Maven lifecycle phases and goals in project management is typically used for projects documentation, dependency and build, making the life of Java developer’s day-to-day work easy and manageable. The open-source tool for enterprise- build takes the burden out of the build process, making it easy to maintain and reduce the time involved in script builds. Besides, it promotes standards for development that is company-wide.

The acronym MAVEN is drawn from Mars Atmosphere and Volatile Evolution, which was used by NASA with a Maven lifecycle to provide character to the Martian atmosphere, reconstruct how and why Mars lost its water and use the data collected to reconstruct Martian climate history.

Maven Lifecycle
Maven Commands

1. Maven Lifecycle

The Maven build lifecycle has 8-stages by default. These are in a particular Maven lifecycle order, as mentioned below.

Validation
Compilation
Testing
Packaging
Integration testing
Verification
Installation
Deployment.

In any Java project, the 8-phases of the Maven build life cycle and what they accomplish are discussed below.

Validation Phase: Here, one ensures that the correct Maven lifecycle project structure is validated. Ex: In this step, the local repository is checked to ensure all dependencies are available and downloaded.
Compilation Phase: In this phase, Maven is used with the source code for compilation wherein the java .files are converted to .class files and then stored in the classes/ target folder as classes.
Testing Phase: Here, Maven runs all project unit tests for a Maven lifecycle.
Packaging Phase: In this phase, the code is compiled into formats like WAR, JAR etc., ensuring a distributable compiled code formatting.
Integration Testing Phase: Maven is responsible for this phase to run the project’s integration tests.
Verification Phase: This phase ensures that the Maven lifecycle project meets the required quality levels and that the project has been validated.
Installation Phase: The local repository of a Maven lifecycle is then subject to the installation of the packaged code.
Deployment Phase: In this phase, the packaged code is copied and deployed to other remote repositories where developers can share the compiled code.

Note that, Maven always follows a sequential order of Maven lifecycle steps. This means if one runs the step-n commands, then all preceding steps of the Maven lifecycle from 1 to n-1 also get executed. Thus if one commands the lifecycle mapping Maven code to install, it will automatically run all the preceding phases and go ahead with validation, compilation, packaging, project verification with the running unit and run all integration testing steps before it moves into the installation of the package to the local Maven repository.

2. Maven Commands

Maven interview questions which are a favourite with interviewers looking to quiz developers on knowledge of Maven, are questions about the Maven commands discussed below.

mvn compile: This command is used to compile the project’s source code.
mvn clean: Here, the project is cleaned to remove all previous-build files generated.
mvn test: With this command, one can run project testing steps.
mvn test-compile: This command is used to compile the code from the test source.
mvn install: This command helps deploys the packaged WAR/JAR files storing them as classes in the local repository.
mvn package: With this Maven lifecycle command, one packages or creates a project WAR or JAR file to be able to use a distributable format.
mvn deploy: The deploy command occurs after compilation, running project tests and project building. Here the packaged WAR/JAR files are copied to the remote repository for use by other developers.

Typically, the Maven clean command is added to the folder targeted to ensure all previous-build files are removed before the running of the new build. On integrating the 2 steps, the command is a clean-step with an install-step and reads mvn clean install command. Similarly, one can add the debug mode to the Maven installation steps by adding –X to the install command, which then reads mvn -X install.

Just in case one decides not to run the tests in the Maven package command for packaging or installation steps of the Java project, one can use the -DskipTests with the install, package or other commands. The command to run the skip mvn test while installing would then read mvn install –DskipTests.

Conclusion

The tool MAVEN is used in the Maven lifecycle management of Java scripted tool project object models. It not only simplifies the ANT build process but meets the Java developer’s needs for a time-saving tool for scriptwriting and maintenance, project dependency, documentation and builds. It is critical to the Maven lifecycle and a potent tool in the understanding of any project that is Java-based. Its ability to create war, jar, etc. Adding new dependencies, easy starts in various environments, enabling processes like processing, build and injection etc., make it the go-to for Java developers. The resource Introduction to Apache Maven is excellent to learn more about the applications, working and installation of MAVEN.

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