maven

Maven

Maven is an project automation tool. All the routine work can be automated by one maven script: e.g. compiling, project1 and project2, generating websites, run the tests.

Maven can manage Maven-artifacts, which are uniquely identified by: groupId, artifactId, version.
Maven artifacts can depend on other Maven artifacts.
Maven downloads required artifacts, which the local artifacts depend from - all into one local repository:
```
C:\Users\<username>\.m2
```
Maven has an own Project type in Eclipse. Each Maven Project is a Maven artifact.

What	Where
1. General “what is maven” description.	What is maven?
2. Project requred fileds: groupId, artifactId, version	Requred fields
3. Maven Phases, and so the commands	Maven phases
4. Further details about Maven	maven.apache.org

Maven

Useful maven resources

What	Where
Maven variables	Listed here A more complete List is here

Glossary

Lifecycle	There is a predefined lifecycle. Maven executed all phases of this lifecycle http://maven.apache.org/guides/introduction/introduction-to-the-lifecycle.html#Built-in_Lifecycle_Bindings
Phase	Generate-sources, compile, test-compile,…, install, deploy
Goal	Goals are executed in phases. (test, jar, install). Goals are defined by plugins. Each executed plugin binds it's goals to predefined phases.
Mojo	Maven Plain Old Java Object. Each Mojo is a goal in maven

Phases

install - installiert in Lokale Repo
deploy - installiert ins Nexus

Goals and Phases

The Syntax to execute a phase

mvn phasename

Examples:

mvn clean
mvn deploy
mvn install

Achtung: Executing a phase - executes all phases up to the executed phase!
Executing:

mvn clean

does

process-resources
compile
process-test-resources
test-compile
test
package
install

The Syntax to execute a goal

mvn myplugin:myGoal

Examples:

mvn jboss-as:deploy
mvn dependency:copy-dependencies

You can mix up executing phases (e.g. clean or package) with goal-execution of some plugins (e.g. dependency:copy-dependencies)
Examples:

mvn clean dependency:copy-dependencies package

Variables in pom.xml

${project.basedir}	main project directory
${project.parent.basedir}	parent pom's directory
${project.parent.parent.basedir}	grand parent pom's directory

Usage

Merging

Child POMs override parent Pom's nodes on default.
How to change this behaviour is described here: http://blog.sonatype.com/people/2011/01/maven-how-to-merging-plugin-configuration-in-complex-projects/

Settings

java.lang.OutOfMemoryError

To avoid this error during mvn clean install assign more space to Java. Use an environment variable MAVEN_OPTS

set MAVEN_OPTS=-Xmx1024m

Abhängigkeiten visualisieren

Visualize on Console

mvn dependency:tree -Dincludes="this.is.your.gorup.id:this.is.the.artifact.id"

Visualize as PNG

mvn org.fusesource.mvnplugins:maven-graph-plugin:RELEASE:reactor

<settings xmlns="http://maven.apache.org/SETTINGS/1.0.0" 
	xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://maven.apache.org/SETTINGS/1.0.0 http://maven.apache.org/xsd/settings-1.0.0.xsd">

	<profiles>
	
		<profile>
			<repositories>
				<repository>
				  <id>maven2-central-remote</id>
				  <name>maven2-central-remote</name>
				  <url>https://mydomain.com/artifactory/maven2-central-remote</url>
				</repository>
				
				<repository>
					<id>maven2-priv</id>
					<name>maven2-priv</name>
					<url>https://mydomain.com/artifactory/maven2-priv</url>
				</repository>

			</repositories>
			
			<pluginRepositories>
			  <pluginRepository>
				<id>maven2-central-remote</id>
				<url>https://mydomain.com/artifactory/maven2-central-remote</url>
			  </pluginRepository>

			  <pluginRepository>
				<id>center</id>
				<url>https://repo1.maven.org/maven2/</url>
			  </pluginRepository>

			  <pluginRepository>
				<id>jcenter</id>
				<url>https://jcenter.bintray.com</url>
			  </pluginRepository>
			  
			  
			</pluginRepositories>
			
			<id>bt</id>
		</profile>
	</profiles>

	<activeProfiles>
		<activeProfile>bt</activeProfile>
	</activeProfiles>


	<proxies>
		<proxy>
			<active>true</active>
			<host>111.122.3.44</host>
			<port>9400</port>
			<nonProxyHosts>mydomain.com|*.mydomain.com</nonProxyHosts>
		</proxy>
	</proxies>
	
	<servers>
		<server>
			<id>maven2-priv</id>
			<username>username@domain.com</username>
			<!-- encrypted pass or api token from artifactory profile -->
			<password>XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX</password>
		</server>
		<server>
			<id>maven2-priv-snap</id>
			<username>username@domain.com</username>
			<!-- encrypted pass or api token from artifactory profile -->
			<password>XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX</password> <!-- encrypted pass -->
		</server>
	</servers>

</settings>

Now you can add the following to your projects pom.xml

<project ....
  <pluginRepositories>
    <pluginRepository>
      <id>maven2-priv</id>
      <url>https://domain.com/artifactory/maven2-priv/</url>
    </pluginRepository>
  </pluginRepositories>
 
  <distributionManagement>
    <repository>
      <uniqueVersion>false</uniqueVersion>
      <id>maven2-priv</id>
      <name>maven2-priv</name>
      <url>https://domain.com/artifactory/maven2-priv</url>
      <layout>default</layout>
    </repository>
    <snapshotRepository>
      <uniqueVersion>false</uniqueVersion>
      <id>maven2-priv-snap</id>
      <name>maven2-priv</name>
      <url>https://domain.com/artifactory/maven2-priv</url>
      <layout>default</layout>
    </snapshotRepository>
  </distributionManagement>
  ...
</project>

# The following command deploys the artifact to the Artifactory.

 
mvn clean install
mvn clean deploy

Version Vodoo

SNAPSHOT

The Word SNAPSHOT is interpreted by Maven, if it is contained inside the version string.
The Word SNAPSHOT is interpreted during install or deploy phases. Inside the target folder the filename will still contain SNAPSHOT. After deploy it will be replaced.
The Word SNAPSHOT is expanded to a qualifier, e.g. to date and time.

Example:

target: 1.0-SNAPSHOT
deploy: 1.0-20080207-230803-1

qualifier

Frther there is an OSGI Version too. It is called qualifier. It is replaced by a timestamp in maven plugins.

Dependency Management and Scope

Maven manages the dependencies transitively. Here are the rules, about how maven resolves dependencies: https://maven.apache.org/guides/introduction/introduction-to-dependency-mechanism.html#Dependency_Scope

Scope is a concept, which allows to say, that dependency X is only available at runtime, or should not be inherited transitively.

Scopes:

compile	This is the default scope, used if none is specified. Compile dependencies are available in all classpaths of a project. Furthermore, those dependencies are propagated to dependent projects.
provided	This is much like compile, but indicates you expect the JDK or a container to provide the dependency at runtime. For example, when building a web application for the Java Enterprise Edition, you would set the dependency on the Servlet API and related Java EE APIs to scope provided because the web container provides those classes. This scope is only available on the compilation and test classpath, and is not transitive.
runtime	This scope indicates that the dependency is not required for compilation, but is for execution. It is in the runtime and test classpaths, but not the compile classpath.
test	This scope indicates that the dependency is not required for normal use of the application, and is only available for the test compilation and execution phases.
system	This scope is similar to provided except that you have to provide the JAR which contains it explicitly. The artifact is always available and is not looked up in a repository.
import	(only available in Maven 2.0.9 or later)This scope is only used on a dependency of type pom in the <dependencyManagement> section. It indicates that the specified POM should be replaced with the dependencies in that POM's <dependencyManagement> section. Since they are replaced, dependencies with a scope of import do not actually participate in limiting the transitivity of a dependency.

Profiles

Syntax to use the profile jetty

mvn clean install -P jetty

Plugins

If you keep the a part of the xml-structure and insert the structure between the <profile></profile> tags.

Define some plugins which will only be used when profile jetty is enabled

		<!-- profile to start jetty -->
		<profile>
			<id>jetty</id>
			<build>
				<plugins>			
					<plugin>
					...
					</plugin>
				</plugins>
			</build>
		</profile>

Properties

You can use properties to configure the usual build

<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
	xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
	<modelVersion>4.0.0</modelVersion>
	<artifactId>de.updatesite.customplugins.site</artifactId>
	<name>de.updatesite</name>
	<description>updatesite</description>
	<packaging>${package.method}</packaging>

		<!-- profile to start jetty will be packaged as pom -->
		<profile>
			<properties>
				<package.method>pom</package.method>
			</properties>
		</profile>
...

Table of Contents

Maven

Maven

Useful maven resources

Glossary

Phases

Goals and Phases

The Syntax to execute a phase

The Syntax to execute a goal

Variables in pom.xml

Usage

Merging

Settings

java.lang.OutOfMemoryError

Abhängigkeiten visualisieren

Visualize on Console

Visualize as PNG

Version Vodoo

SNAPSHOT

qualifier

Dependency Management and Scope

Profiles

Plugins

Properties