Intermediate MavenIntermediate MavenMichael Youngstrom

Notes

• This is a training NOT a presentation• Please ask questions• Prerequisites– Introduction to Maven– Basic Java and XML skillz

• Review Introduction to Maven• Plugins• Properties• Profiles

Review

• Maven is a build tool• Maven project Structure• Maven has a build lifecycle• A maven artifact is identified with GAV• Maven dependencies are glorious!

Maven Plugins

• Plugins extend Maven• Plugins are identified with GAV• Two ways to execute a plugin– Hook into build lifecycle– Invoke standalone

Hooking into build lifecycle

• Allows plugin to execute as part of maven build• Three items to configure a plugin:– Phase– Goal– Configuration

Plugin Example<project> ... <build> <plugins> <plugin> <groupId>org.apache.maven.plugins</groupId> <artifactId>maven-enforcer-plugin</artifactId> <version>1.0</version> <configuration> ... </configuration> <executions> <execution> <id>execute</id> <phase>validate</phase> <goals><goal>enforce</goal></goals> <configuration> ... </configuration> </execution> </executions> </plugin> </plugins> </build></project>

Plugin Documentation

• Use Plugin reference documentation!

Full Name

Default Phase

Configuration

Plugin Configuration

• Configuration parameters go in the configuration element.<project> ... <plugin> ... <configuration> <fail>false</fail> </configuration> <executions> <execution> ... <configuration> <failFast>true</failFast> </configuration> </execution> </executions> </plugin></project>

PluginManagement

• PluginManagement configures a plugin without executing it– Version– Configuration– Executions

• To execute use:– Regular Plugin entry– Plugin command

Plugin Mangement Example

<project> <build> <pluginManagement> <plugins> <plugin> <groupId>org.apache.maven.plugins</groupId> <artifactId>maven-enforcer-plugin</artifactId> <version>1.0</version> <configuration> ... <ignoreCache>true</ignoreCache> </configuration> </plugin> </plugins> </pluginManagement> <plugins> <plugin> <groupId>org.apache.maven.plugins</groupId> <artifactId>maven-enforcer-plugin</artifactId> </plugin> </plugins> </build></project>

Plugin Inheritance

• This is a complex world!• Configuration– Plugin Inherits PluginManagement configuration– First level configuration elements are inherited– Execution configuration extend base configuration

How to Mange POM Complexity

• Effective POM– Flattens POM configuration– Dependency and DependencyMangement is resolved– Plugin and PluginManagement is resolved– Executions are Resolved– Properties are Resolved (more on this later)– Profiles are Resolved (more on this later)

• To use:– Select the “Effective POM” tab in pom editor in Eclipse– Invoke mvn help:effective-pom on command line

Invoking Plugins Standalone

• Plugins can also be invoked adhoc from command line– GroupId:ArtifactId:Version:Goal– Will use Plugin Management configuration

• Can be shortened

• Must be configured in pom plugin or in settings.xml

mvn org.apache.maven.plugins:maven-enforcer-plugin:1.0:enforce

mvn enforcer:enforce

Plugin Documentation Helps

• Plugin reference documentation is your friend!Short Name

Full Name

Setting Configuration Standalone

• Expression: shows the key to this parameter

Expression Key

mvn enforcer:enforce –Denforcer.fail=false

Lab 1: Maven Plugins

https://tech.lds.org/wiki/Intermediate_Maven#Lab_1_Maven_Plugins

Maven Properties

• Properties are the glue that tie configuration together• Properties can come from many places:– <properties/> element in pom– System Properties– Project Object Model– Inherited from parent

• Properties can be used as a value just about anywhere– Plugin Configuration– Resource Filtering

• Properties can only be simple primitive values• Properties follow the syntax ${someProperty}

Maven Property Example

<project> ... <properties> <skipEnforcer>true</skipEnforcer> </properties> <build> <plugins> <plugin> <groupId>org.apache.maven.plugins</groupId> <artifactId>maven-enforcer-plugin</artifactId> <version>1.0</version> <configuration> <skip>${skipEnforcer}</skip> </configuration> </plugin> </plugins> </build></project>

POM Properties Element

• Properties can be nested

<project> ... <properties> <skipTests>true</skipTests> <skipEnforcer>${skipTests}</skipEnforcer> </properties></project>

• System Properties override POM properties

System Properties

• Supplied to the command line using “-D”– mvn install –DskipEnforcer=true

• Supplied in the IDE using parameters dialog• System Properties override POM properties

Project Object Model Properties

• Properties can be derived from POM structure• POM elements = property keys– Expression: ${project.version}

• Element: <project><version/></project>– Expression: ${project.artifactId}

• Element: <project><artifactId/></project>– Expression: ${project.build.sourceDirectory

• <project><build><sourceDirectory/></build></project>• Special properties:– ${basedir}: Directory of current project– ${maven.build.timestamp} : Start of build.

Inherited Properties

• Properties can be inherit and overridden

<project> ... <properties> <skipTests>true</skipTests> <skipEnforcer>${skipTests}</skipEnforcer> </properties></project>

<project> <parent> ... </parent> <properties> <skipTests>false</skipTests> </properties></project>

Resource Filtering

• Project resources can use properties• Resources filtered in process-resources phase• Filtering can be turned off on a per resource

directory basis

Some Text File in /src/main/resources:${someProperty}

Some Text File in /src/main/resources:SomeValue

<project> ... <properties> <someProperty>SomeValue</someProperty> </properties></project>

Properties and Plugin Expression

• Properties can also override plugin expression defaults

Expression Key

Skip Enforcer Example #1

<project> ... <plugin> <groupId>org.apache.maven.plugins</groupId> <artifactId>maven-enforcer-plugin</artifactId> <version>1.0</version> <configuration> <skip>true</skip> </configuration> </plugin></project>

Skip Enforcer Example #2

<project> <properties> <enforcer.skip>true</enforcer.skip> </properties> <build> <plugin> <groupId>org.apache.maven.plugins</groupId> <artifactId>maven-enforcer-plugin</artifactId> <version>1.0</version> </plugin> </build></project>

Skip Enforcer Example #3

<project> <build> <plugin> <groupId>org.apache.maven.plugins</groupId> <artifactId>maven-enforcer-plugin</artifactId> <version>1.0</version> </plugin> </build></project>

mvn clean install –Denforcer.skip=true

Lab 2: Maven Properties

https://tech.lds.org/wiki/Intermediate_Maven#Lab_2_Maven_Properties

Maven Profile

• Allows activating a set of alternative configurations

• Works for:– Properties– Dependencies– Plugins– etc.

• Inherits and extends non-profile configuration

Profile Example

<project> ... <profiles> <profile> <id>enforcer</id> <activation/> <properties> <enforcer.skip>false</enforcer.skip> </properties> </profile> </profiles></project>

Profile Activation

• Can be Activated:– By Default– Explicitly by name– Based on a Property– Based on operation system– Existence of a file

Activation from Command Line

• Activates a profile explicitly• Multiple profile ids are comma delimited

mvn clean install –P enforcer

Activation in IDE Build

• Can be set in build command configuration

Activation in IDE Development

• Can be set in project’s Maven config• Usually used to change development mode

Lab 3: Maven Profiles

https://tech.lds.org/wiki/Intermediate_Maven#Lab_3_Maven_Profiles

Summary

• Plugins extend Maven’s capabilities• Properties are the glue in Maven configuration• Profiles enable alternate configurations• Next training understanding Stack Starter’s

Maven Configuration