What are Maven goals and phases and what is their difference

Question

What is the difference relation between Maven goals and phases  How they are related to each other

User · Answer

Maven working terminology having phases and goals.

Phase:Maven phase is a set of action which is associated with 2 or 3 goals

exmaple:- if you run mvn clean

this is the phase will execute the goal mvn clean:clean

Goal:Maven goal bounded with the phase

for reference http://books.sonatype.com/mvnref-book/reference/lifecycle-sect-structure.html

User · Answer

Credit to Sandeep Jindal and Premraj  Their explanation help me to understand after confused about this for a while   I created some full code examples  amp  some simple explanations here https   www surasint com maven-life-cycle-phase-and-goal-easy-explained    I think it may help others to understand   In short from the link  You should not try to understand all three at once  first you should understand the relationship in these groups    Life Cycle vs Phase  Plugin vs Goal   1  Life Cycle vs Phase   Life Cycle is a collection of phase in sequence see here Life Cycle References  When you call a phase  it will also call all phase before it   For example  the clean life cycle has 3 phases  pre-clean  clean  post-clean     mvn clean   It will call pre-clean and clean    2  Plugin vs Goal  Goal is like an action in Plugin  So if plugin is a class  goal is a method   you can call a goal like this   mvn clean clean   This means  call the clean goal  in the clean plugin   Nothing relates to the clean phase here  Don t let the word clean  confusing you  they are not the same    3  Now the relation between Phase  amp  Goal   Phase can  pre links to Goal s  For example  normally  the clean phase links to the clean goal  So  when you call this command   mvn clean   It will call the pre-clean phase and the clean phase which links to the clean clean goal   It is almost the same as   mvn pre-clean clean clean   More detail and full examples are in https   www surasint com maven-life-cycle-phase-and-goal-easy-explained

User · Answer

Life cycle is a sequence of named phases    Phases executes sequentially  Executing a phase means executes all previous phases       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     Maven is based around the central concept of a Build Life Cycles   Inside each Build Life Cycles there are Build Phases  and inside each Build Phases there are Build Goals      We can execute either a build phase or build goal  When executing a build phase we execute all build goals within that build phase  Build goals are assigned to one or more build phases  We can also execute a build goal directly     There are three major built-in Build Life Cycles    default clean  site   Each Build Lifecycle is Made Up of Phases     For example the default lifecycle comprises of the following Build Phases     validate - validate the project is correct and all necessary information is available  compile - compile the source code of the project  test - test the compiled source code using a suitable unit testing framework  These tests should not require the code be packaged or deployed  package - take the compiled code and package it in its distributable format  such as a JAR   integration-test - process and deploy the package if necessary into an environment where integration tests can be run  verify - run any checks to verify the package is valid and meets quality criteria  install - install the package into the local repository  for use as a dependency in other projects locally  deploy - done in an integration or release environment  copies the final package to the remote repository for sharing with other developers and projects    So to go through the above phases  we just have to call one command     mvn  lt phase gt    Ex  mvn install     For the above command  starting from the first phase  all the phases are executed sequentially till the    install    phase  mvn can either execute a goal or a phase  or even multiple goals or multiple phases  as follows     mvn clean install plugin goal     However  if you want to customize the prefix used to reference your plugin  you can specify the prefix directly through a configuration parameter on the maven-plugin-plugin in your plugin s POM   A Build Phase is Made Up of Plugin Goals  Most of Maven s functionality is in plugins  A plugin provides a set of goals that can be executed using the following syntax      mvn  plugin-name   goal-name    For example  a Java project can be compiled with the compiler-plugin s compile-goal by running mvn compiler compile      Build lifecycle is a list of named phases that can be used to give order to goal execution   Goals provided by plugins can be associated with different phases of the lifecycle  For example  by default  the goal compiler compile is associated with the compile phase  while the goal surefire test is associated with the test phase  Consider the following command     mvn test   When the preceding command is executed  Maven runs all goals associated with each of the phases up to and including the test phase  In such a case  Maven runs the resources resources goal associated with the process-resources phase  then compiler compile  and so on until it finally runs the surefire test goal   However  even though a build phase is responsible for a specific step in the build lifecycle  the manner in which it carries out those responsibilities may vary  And this is done by declaring the plugin goals bound to those build phases   A plugin goal represents a specific task  finer than a build phase  which contributes to the building and managing of a project  It may be bound to zero or more build phases  A goal not bound to any build phase could be executed outside of the build lifecycle by direct invocation  The order of execution depends on the order in which the goal s  and the build phase s  are invoked  For example  consider the command below  The clean and package arguments are build phases  while the dependency copy-dependencies is a goal  of a plugin    mvn clean dependency copy-dependencies package   If this were to be executed  the clean phase will be executed first  meaning it will run all preceding phases of the clean lifecycle  plus the clean phase itself   and then the dependency copy-dependencies goal  before finally executing the package phase  and all its preceding build phases of the default lifecycle      Moreover  if a goal is bound to one or more build phases  that goal will be called in all those phases     Furthermore  a build phase can also have zero or more goals bound to it  If a build phase has no goals bound to it  that build phase will not execute  But if it has one or more goals bound to it  it will execute all those goals     Built-in Lifecycle Bindings Some phases have goals bound to them by default  And for the default lifecycle  these bindings depend on the packaging value   Maven Architecture       Reference 1 Reference 2  Eclipse sample for Maven Lifecycle Mapping

User · Answer

I believe a good answer is already provided  but I would like to add an easy-to-follow diagram of the different 3 life-cycles  build  clean  and site  and the phases in each     The phases in bold - are the main phases commonly used

User · Answer

The definitions are detailed at the Maven site s page Introduction to the Build Lifecycle  but I have tried to summarize    Maven defines 4 items of a build process    Lifecycle  Three built-in lifecycles  aka build lifecycles   default  clean  site   Lifecycle Reference  Phase  Each lifecycle is made up of phases  e g  for the default lifecycle  compile  test  package  install  etc  Plugin  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  Goal  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    a phase  e g clean  package   lt plugin-prefix gt   lt goal gt   e g  dependency copy-dependencies   lt plugin-group-id gt   lt plugin-artifact-id gt    lt plugin-version gt    lt goal gt   e g  org apache maven plugins maven-compiler-plugin 3 7 0 compile    with one or more combinations of any or all  e g    mvn clean dependency copy-dependencies package

User · Answer

Goals are executed in phases which help determine the order goals get executed in   The best understanding of this is to look at the default Maven lifecycle bindings which shows which goals get run in which phases by default   The compile phase goals will always be executed before the test phase goals  which will always be executed before the package phase goals and so on  Part of the confusion is exacerbated by the fact that when you execute Maven you can specify a goal or a phase   If you specify a phase then Maven will run all phases up to the phase you specified in order  e g  if you specify package it will first run through the compile phase and then the test phase and finally the package phase  and for each phase it will run all goals attached to that phase  When you create a plugin execution in your Maven build file and you only specify the goal then it will bind that goal to a given default phase   For example  the jaxb xjc goal binds by default to the generate-resources phase   However  when you specify the execution you can also explicitly specify the phase for that goal as well  If you specify a goal when you execute Maven then it will run that goal and only that goal   In other words  if you specify the jar jar goal it will only run the jar jar goal to package your code into a jar   If you have not previously run the compile goal or prepared your compiled code in some other way this may very likely fail

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There are following three built-in build lifecycles    default clean site   Lifecycle default -   validate  initialize  generate-sources  process-sources  generate-resources  process-resources  compile  process-classes  generate-test-sources  process-test-sources  generate-test-resources  process-test-resources  test-compile  process-test-classes  test  prepare-package  package  pre-integration-test  integration-test  post-integration-test  verify  install  deploy   Lifecycle clean -   pre-clean  clean  post-clean   Lifecycle site -   pre-site  site  post-site  site-deploy   The flow is sequential  for example  for default lifecycle  it starts with validate  then initialize and so on     You can check the lifecycle by enabling debug mode of mvn i e   mvn -X  lt your goal gt

User · Answer

The chosen answer is great  but still I would like to add something small to the topic  An illustration   It clearly demonstrates how the different phases binded to different plugins and the goals that those plugins expose   So  let s examine a case of running something like mvn compile    It s a phase which execute the compiler plugin with compile goal Compiler plugin got different goals  For mvn compile it s mapped to a specific goal  the compile goal  It s the same as running mvn compiler compile   Therefore  phase is made up of plugin goals      Link to the reference

[maven] What are Maven goals and phases and what is their difference?

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