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Maven - Lifecycles (Build／Clean／Site) - Phases - Goals - Plugins

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Maven defines 4 items of a build process:

Lifecycles

Three built-in lifecycles (aka build lifecycles): default, clean, site. (Lifecycle Reference)

Phases

Each lifecycle is made up of phases, e.g. for the default lifecycle: compile, test, package, install, etc

Plugins

An artifact that provides one or more goals

Based on packaging type (jar, war, etc.) plugins’ goals are bound to phases by default. (Built-in Lifecycle Bindings)

Goals

The task (action) that is executed. A plugin can have one or more goals.

One or more goals need to be specified when configuring a plugin in a POM. Additionally, in case a plugin does not have a default phase defined, the specified goal(s) can be bound to a phase

Maven can be invoked with:

  1. a phase (e.g clean, package)
  2. <plugin-prefix>:<goal> (e.g. dependency:copy-dependencies)
  3. <plugin-group-id>:<plugin-artifact-id>[:<plugin-version>]:<goal> (e.g. org.apache.maven.plugins:maven-compiler-plugin:3.7.0:compile)

with one or more combinations of any or all:

  • mvn clean dependency:copy-dependencies package

More Details

maven contains 3 built-in life cycles:

  • default (build): the main life cycle as it’s responsible for project deployment
  • clean: to clean the project and remove all files generated by the previous build
  • site: to create the project’s site documentation

Each life cycle consists of a sequence of phases:

  • default build life cycle consists of 23 phases as it’s the main build lifecycle
  • clean life cycle consists of 3 phases
  • site lifecycle is made up of 4 phases

A phase represents a stage in the Maven build lifecycle

Here are some of the most important phases in the default build lifecycle:

  • validate: check if all information necessary for the build is available
  • compile: compile the source-code
  • test-compile: compile the test-source-code
  • test: run unit tests
  • package: package compiled source-code into the distributable format (jar, war, …)
  • integration-test: process and deploy the package if needed to run integration tests
  • install: install the package to a local repository
  • deploy: copy the package to the remote repository

For the full list of each lifecycle’s phases, check out the Maven Reference.

commands:

  • Run lifecycle up to phase: mvn $PHASE

Each phase is a sequence of goals

Here are some of the phases and default goals bound to them:

  • compiler:compile – the compile goal from the compiler plugin is bound to the compile phase
  • compiler:testCompile is bound to the test-compile phase
  • surefire:test is bound to test phase
  • install:install is bound to install phase
  • jar:jar and war:war is bound to package phase

commands:

  • List all goals bound to a phase and their plugins: mvn help:describe -Dcmd=$PHASE

A plugin is a group of goals. However, these goals aren’t necessarily all bound to the same phase

commands:

  • list all goals in a specific plugin: mvn $PLUGIN:help
  • run a specific goal, without executing its entire phase (and the preceding phases): mvn $PLUGIN:$GOAL

A plugin is a collection of goals also called MOJO (Maven Old Java Object).

Analogy: Plugin is a class and goals are methods within the class

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