Maven Lifecycle and Goals
The previous section covered plugin goals and how to run goals from command line. In very few situations we invoke plugin goals directly and more often than not, lifecycle phases are preferred. In this chapter, we describe the link between Maven Lifecycle and Goals.
Lifecycle Phases and Plugin Goals
When a lifecycle phase is run, depending on project type and packaging type, Maven binds plugin goals to lifecycle phases.
When we run
mvn package in a Java Project, Maven binds plugin goals to
lifecycle phases as shown in the next figure.
To process-resources phase, Maven binds resources goal of maven-resources-plugin and to test phase, it binds test goal of maven-surefire-plugin and so on.
What’s happens at package phase is bit interesting. In a Java Project, Maven binds jar goal of maven-jar-plugin. However, when we run the same command in a webapp project, up to test phase Maven binds same goals, but to the package phase Maven binds war goal of maven-war-plugin the war:war instead of jar:jar.
mvn help:describe -Dcmd=<phase> is a very useful command
not only to list the lifecycle phases but also to know the binded goal
and plugin version. Run the following command from the project directory
that contains the pom.xml.
$ mvn help:describe -Dcmd=clean
[INFO] ’clean’ is a lifecycle with the following phases:
* pre-clean: Not defined
* clean: org.apache.maven.plugins:maven-clean-plugin:2.5:clean
* post-clean: Not defined
We pass lifecycle phase
clean with argument
help:describe validates the pom.xml and based on project type outputs
the sequence of lifecycle phases that will be executed for the lifecycle
and plugin goals bounded to each phase. As we can see in the screenshot,
no goals are bounded to pre-clean and post-clean phases and they are
indicated as not defined and for clean phase, clean:clean goal of
maven-clean-plugin (version 2.5) is attached.
The following command outputs the sequence of phases and goals for default lifecycle The phase deploy belongs to default lifecycle so command output details of default lifecycle.
$ mvn help:describe -Dcmd=deploy
It is a part of the lifecycle for the POM packaging
jar. This lifecycle includes the following phases:
* validate: Not defined
* initialize: Not defined
* generate-sources: Not defined
* process-sources: Not defined
* generate-resources: Not defined
* process-resources: org.apache.maven.plugins:maven-resources-plugin:2.6:resources
* compile: org.apache.maven.plugins:maven-compiler-plugin:3.1:compile
* process-classes: Not defined
* generate-test-sources: Not defined
* process-test-sources: Not defined
* generate-test-resources: Not defined
* process-test-resources: org.apache.maven.plugins:maven-resources-plugin:2.6:testResources
* test-compile: org.apache.maven.plugins:maven-compiler-plugin:3.1:testCompile
* process-test-classes: Not defined
* test: org.apache.maven.plugins:maven-surefire-plugin:2.12.4:test
* prepare-package: Not defined
* package: org.apache.maven.plugins:maven-jar-plugin:2.4:jar
* pre-integration-test: Not defined
* integration-test: Not defined
* post-integration-test: Not defined
* verify: Not defined
* install: org.apache.maven.plugins:maven-install-plugin:2.4:install
* deploy: org.apache.maven.plugins:maven-deploy-plugin:2.7:deploy
Lifecycles, Lifecycle Phases, Plugins and Plugin Goals are the core of Maven and lets’ go through the concepts learned so far:
Maven comes with three lifecycles - default, clean and site.
each lifecycle is made up of lifecycle phases and in all, there are 28 phases - default 21, clean 3 and site 4.
when a lifecycle phase is invoked using mvn command, all preceding phases are executed sequentially one after another.
lifecycle phases by themselves doesn’t have any capabilities to accomplish some task and they rely on plugins to carryout the task.
depending on project and packaging type, Maven binds various plugin goals to lifecycle phases and goals carryout the task entrusted to them.
So far, we depended upon the out-of-the-box functionality of Maven, but we can accomplish much more through the pom.xml (POM). In the next tutorial, we cover the plugin configuration.