Maven Concepts: Difference between revisions
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==Classifier== | ==Classifier== | ||
You may occasionally find a fifth element on the coordinate, and that is the classifier. We will visit the classifier later, but for now it suffices to know that those kinds of projects are displayed as . | |||
=POM= | =POM= | ||
Revision as of 16:50, 4 November 2016
Internal
Maven Coordinates
groupId:artifactId:version is the minimum amount of information to fully and unequivocally identify an artifact, and constitute an address and a timestamp. This information is referred to as maven coordinates. More details about each component below.
Group ID
The group ID is an unique identifier (ideally, globally) for a project. It is specified as <groupId> at the top of the POM file.
Conventionally uses a dot notation, but it does not have to. When it does use the dot notation, the groupId does NOT have to correspond to the package structure of the project it designates; it is, though, a good practice to follow. When stored within a repository, the dots are replaced by OS specific directory separators, which becomes a relative directory structure from the base repository.
Artifact ID
The artifact ID is generally the name that the project is known by. It is specified as < artifactId> at the top of the POM file. The artifact ID, along with the group ID, create a key that ideally separates this project from every other project in the world.
Version
The version represents a timestamp for a specific incarnation of the project's artifact, in the history of the project. The information is used within an artifact's repository to separate versions from each other. It is specified as <version> at the top of the POM file.
Packaging
The packaging represents the project's artifact type. It is specified as <packaging> at the top of the POM file.
When no packaging is declared, Maven assumes the artifact is, by default, a "jar". The valid types are Plexus role-hints of the component role org.apache.maven.lifecycle.mapping.LifecycleMapping. The current core packaging values are: "pom", "jar", "maven-plugin", "ejb", "war", "ear", "rar" and "par". These define the default list of goals which execute to each corresponding build lifecycle stage for a particular package structure.
If you need to specify packaging in the Maven coordinates of a project, it is specified after artifact ID: groupId:artifactId:packaging:version.
Classifier
You may occasionally find a fifth element on the coordinate, and that is the classifier. We will visit the classifier later, but for now it suffices to know that those kinds of projects are displayed as .
POM
Profile
Lifecycle
System Properties
System properties can be declared and exposed to the build in the <properties> section of pom.xml. See: