Using Maven2
Free Maven Books
Maven: The Definitive Guide (alpha)www.sonatype.com/book
Better Builds with Mavenwww.mergere.com
The Maven Site
http://maven.apache.org/
What is Maven?
Build lifecycle Dependency management tool Artifact repository Collection of plugins Project reporting tool Set of conventions Distilled experience
What Else is Maven?
Succinct command line tool Designed for Java/Java EE/other Holder/publisher of project documentation Generator of project metrics Customisable: environment, lifecycle, etc Inheritable Declarative Encourager of modularity and reuse Integrated with SCM tools Integrated with IDEs Integrated with Ant System of repositories Project kick starter Release manager Deployer Enabler of portable build knowledge Encourager of best practice Community Not perfect
Quick Start
Download Maven2, unzip, add bin directory to $PATH Configure proxy in ~/.m2/settings.xml if required
$ mvn archetype:create \-DgroupId=com.example \-DartifactId=my-app
Directory StructureConvention
Java sources:src/main/java
Unit tests:src/test/java
pom.xml
pom.xml –The Project Object Model
<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/maven-v4_0_0.xsd"> <modelVersion>4.0.0</modelVersion> <groupId>com.example</groupId> <artifactId>my-app</artifactId> <packaging>jar</packaging> <version>1.0-SNAPSHOT</version> <name>my-app</name> <url>http://maven.apache.org</url> <dependencies> <dependency> <groupId>junit</groupId> <artifactId>junit</artifactId> <version>3.8.1</version> <scope>test</scope> </dependency> </dependencies></project>
Directory Structure Convention
Added: My app sources
Properties file:src/main/resources/ messages.poperties
My unit test
Killer App
package com.example;
public class Hello { public static void main(String[] args){ ResourceBundle messages = ResourceBundle.getBundle("messages"); MessagePrinter mp = new MessagePrinter(); mp.printMessage(messages.getString("message1"), System.out); mp.printMessage("\n", System.out); }}
public class MessagePrinter { public void printMessage(String message, OutputStream os){ PrintWriter pw = new PrintWriter(os); pw.print(message); pw.flush(); }}
My Application POM
<project ...> ... <name>My Application</name> <url>http://localhost:8080/my-app</url> ... <build> <plugins> <plugin> <artifactId>maven-jar-plugin</artifactId> <configuration> <archive> <manifest> <mainClass>com.example.Hello</mainClass> </manifest> </archive> </configuration> </plugin> </plugins> </build></project>
Eclipse Integration
Maven2 plugin for Eclipse; either from project root execute:
$ mvn eclipse:eclipse
and import with Eclipse, or create the project in Eclipse and add the Maven2 project nature
Eclipse Integration
Ready for Take Off
$ mvn package
stdout[INFO] Scanning for projects...[INFO] ----------------------------------------------------------------------------[INFO] Building My Application[INFO] task-segment: [package][INFO] ----------------------------------------------------------------------------[INFO] [resources:resources][INFO] Using default encoding to copy filtered resources.[INFO] [compiler:compile][INFO] Compiling 1 source file to /home/russell/Desktop/maven-presentation/example/my-app/target/classes[INFO] [resources:testResources][INFO] Using default encoding to copy filtered resources.[INFO] [compiler:testCompile][INFO] Compiling 1 source file to /home/russell/Desktop/maven-presentation/example/my-app/target/test-classes[INFO] [surefire:test][INFO] Surefire report directory: /home/russell/Desktop/maven-presentation/example/my-app/target/surefire-reports
------------------------------------------------------- T E S T S-------------------------------------------------------Running com.example.AppTestTests run: 1, Failures: 0, Errors: 0, Skipped: 0, Time elapsed: 0.022 sec
Results :
Tests run: 1, Failures: 0, Errors: 0, Skipped: 0
[INFO] [jar:jar][INFO] Building jar: /home/russell/Desktop/maven-presentation/example/my-app/target/my-app-1.0-SNAPSHOT.jar[INFO] ------------------------------------------------------------------------[INFO] BUILD SUCCESSFUL[INFO] ------------------------------------------------------------------------[INFO] Total time: 3 seconds[INFO] Finished at: Wed Jul 04 11:11:55 NZST 2007[INFO] Final Memory: 4M/11M[INFO] ------------------------------------------------------------------------
The (Almost)Finished Product
Classes and test classes compiled
Resources copied to classes directory
Test reports created Jar file created
$ java -jar my-app-1.0-SNAPSHOT.jarHello World!
Plugins & Goals
A plugin contains one or more goals(Goal a.k.a. Mojo; Maven + Pojo = Mojo ?!@!)
A plugin is a Maven artifact A goal is uniquely referenced/invoked by:
groupId:artifactId:version:goal
e.g: org.apache.maven.plugins:maven-eclipse-plugin:eclipsedefaults shorten this to: eclipse:eclipse
Anatomy of a Maven Command
1. Invoke a specific goal:$ mvn [options] plugin:goal [parameter]...
e.g:$ mvn -e eclipse:eclipse
-> Generate Eclipse configuration, print verbose error messages
2. Invoke goals bound to the lifecycle(s) up to and including a phase:
$ mvn [options] phase... [parameter]...
e.g:$ mvn clean package -Dmaven.test.skip=true
-> Clean target, build package, skip tests
Maven Lifecycles
Three built-in lifecycles: default clean site
You can create your own lifecycle, but only if you have really weird build requirements!
The Default Build Lifecycle
Project Packaging
<project ...> <modelVersion>4.0.0</modelVersion> <groupId>com.example</groupId> <artifactId>my-app</artifactId> <packaging>jar</packaging> <version>1.0-SNAPSHOT</version> ...</project>
Lifecycle Bindings
Build Lifecycle
$ mvn package
stdout[INFO] Scanning for projects...[INFO] ----------------------------------------------------------------------------[INFO] Building My Application[INFO] task-segment: [package][INFO] ----------------------------------------------------------------------------[INFO] [resources:resources][INFO] Using default encoding to copy filtered resources.[INFO] [compiler:compile][INFO] Compiling 1 source file to /home/russell/Desktop/maven-presentation/example/my-app/target/classes[INFO] [resources:testResources][INFO] Using default encoding to copy filtered resources.[INFO] [compiler:testCompile][INFO] Compiling 1 source file to /home/russell/Desktop/maven-presentation/example/my-app/target/test-classes[INFO] [surefire:test][INFO] Surefire report directory: /home/russell/Desktop/maven-presentation/example/my-app/target/surefire-reports
------------------------------------------------------- T E S T S-------------------------------------------------------Running com.example.AppTestTests run: 1, Failures: 0, Errors: 0, Skipped: 0, Time elapsed: 0.022 sec
Results :
Tests run: 1, Failures: 0, Errors: 0, Skipped: 0
[INFO] [jar:jar][INFO] Building jar: /home/russell/Desktop/maven-presentation/example/my-app/target/my-app-1.0-SNAPSHOT.jar[INFO] ------------------------------------------------------------------------[INFO] BUILD SUCCESSFUL[INFO] ------------------------------------------------------------------------[INFO] Total time: 3 seconds[INFO] Finished at: Wed Jul 04 11:11:55 NZST 2007[INFO] Final Memory: 4M/11M[INFO] ------------------------------------------------------------------------
Dependencies
<project ...> ... <dependencies> <dependency> <groupId>junit</groupId> <artifactId>junit</artifactId> <version>3.8.1</version> <scope>test</scope> </dependency> </dependencies></project>
Explicitly declared, including version Resolved by Maven, not required in project
directory / source control repository Scoped: compile, provided, runtime, test SNAPSHOT dependencies updated Transitive Strictly acyclic (a DAG not a tree)
Killer App Reloaded
public class Hello { public static void main(String[] args) { ReloadableResourceBundleMessageSource messages = new ReloadableResourceBundleMessageSource(); messages.setCacheSeconds(1); messages.setBasename("messages"); MessagePrinter mp = new MessagePrinter(); Scanner scanner = new Scanner(System.in); do { String message = messages.getMessage("message1", null, Locale.getDefault()); mp.printMessage(message, System.out); mp.printMessage("\n", System.out); mp.printMessage("Keep playing? [Y/n]\n", System.out); } while (!"n".equals(scanner.nextLine())); }}
Dependencies
<project ...> ... <dependencies> <dependency> <groupId>org.springframework</groupId> <artifactId>spring-context</artifactId> <version>[2.0,)</version> <exclusions> <exclusion> <groupId>org.springframework</groupId> <artifactId>spring-aop</artifactId> </exclusion> ... </project>
Version ranges Use exclusions to trim unwanted
dependencies
Transitive Dependencies
Reloadable Message SourceHello World!Keep playing? [Y/n]yHello Again World!Keep playing? [Y/n]n
Note for anyone trying this at home: there's a bit of classpath config required to get this working nicely. It's easiest to run it on the Eclipse console, and modify the target messages.properties
Configuring Pluginse.g. Ant
<project...> ... <build> <plugins> <plugin> <artifactId>maven-antrun-plugin</artifactId> <executions> <execution> <phase>generate-sources</phase> <configuration> <tasks> <!-- Place any ant task here. You can add anything you can add between <target> and </target> in a build.xml. --> </tasks> </configuration> <goals> <goal>run</goal> </goals> </execution> </executions> </plugin> </plugins> </build></project>
StandardMaven Plugins
cleancompilerdeployinstallresourcessitesurefireverifierearejbjarrarwarchangelog
changescheckstylecloverdoapdocckjavadocjxrpmdproject-info-reportssurefire-reportantantlrantrunarchetype
assemblydependencyenforcergpghelpinvokeronepluginreleaseremote-resourcesrepositoryscmsourceeclipse
ideaCodehaus:build-helpercastorjavaccjdependnativesqltaglistOther:cargojaxmejettyjalopy
Listed at: http://maven.apache.org/plugins/
POM Inheritance
<project> <modelVersion>4.0.0</modelVersion> <groupId>com.example</groupId> <artifactId>my-app</artifactId> <version>1.0-SNAPSHOT</version></project>
No source or target defined in POM, yet this works:
$ mvn compile
Super POM
<project> <build> ... <outputDirectory>target/classes</outputDirectory> ... <sourceDirectory>src/main/java</sourceDirectory> ... <resources> <resource> <directory>src/main/resources</directory> </resource> </resources> ... </build></project>
To fully resolve the POM:$ mvn help:effective-pom | less
POM Inheritance
<project> <parent> <groupId>com.example</groupId> <artifactId>org-pom</artifactId> <version>1</version> </parent> <groupId>com.example</groupId> <artifactId>my-app</artifactId> ...</project>
<project> <groupId>com.example</groupId> <artifactId>org-pom</artifactId> <version>1</version> <!-- configure JDK version, e.g: 1.5 standard reports, etc. --></project>
Maven Repositories
Repositories store artifacts: plugins project dependencies
Central: http://repo1.maven.org/maven2(or mirror)
Local: ~/.m2/repository
The first execution of a plugin, or requirement for a dependency pulls the artifact from central and caches it locally
Maven Repositories
Problems: Reliant on network and
external repository for dependencies and plugins
Can't deploy to Central Maven repository for reuse as dependencies of other projects (though usually wouldn't want to)
Organisation Repository
No longer reliant on network or external repository for dependencies and plugins
Can deploy to organisation repository in order to share artifacts
Multiple repository configurations possible
Multiple repository tools available: Archiva, Proximity, Artifactory
Archiva
Install and Deploy
$ mvn deploy
Install and Deploy
$ mvn deploy
SCM Integration
Fully implemented: Bazaar CVS Mercurial Perforce StarTeam Subversion CM Synergy
Partially implemented: ClearCase File system Visual Source Safe
Configuring SCM
<project> <groupId>com.example</groupId> <artifactId>my-app</artifactId> ... <scm> <connection> scm:svn:http://example.com/svn-read/my-app/trunk </connection> <developerConnection> scm:svn:http://example.com/svn-dev/my-app/trunk </developerConnection> <url> http://example.com/view.cvs </url> </scm></project>
SCM Integration,What For?
Use SCM agnostic commands:$ mvn scm:checkin -Dmessage="to the cause"$ mvn scm:update
Project bootstrapping: $ mvn scm:bootstrap
Available for use by Maven tools, e.g: documented and linked in project website, published in Archiva summary
Continuous Integration, SCM details located in project rather than CI tool
Release management
Cutting a Release
$ mvn release:prepare [-DdryRun=true] Checks SCM for modifications Checks for use of SNAPSHOT dependencies or plugins Runs $ mvn clean integration-test Requests release info:
version numbers Creates new POMs:
pom.xml for tag pom.xml for next version release-pom.xml
Creates tag in SCM$ mvn release:perform Uses release-pom.xml, deploys
project, generates site, etc.
Website / Reports (1)
Project website: Conventions for structuring documentation,
supporting various formats: DocBook simple, FML, XDOC, APT, Twiki
Directory structure conventions, supporting multiple types of documentation, e.g: public, user, developer, etc.
Configurable, skinnable site Project info from POM: contact details: organisation,
developers; SCM details, etc.
Website / Reports (2)
Metrics, checks, and project reports (on website): Javadoc Test results Code coverage (Cobertura) Checkstyle, PMD, JDepend, Clirr Database documentation (Hibernate) Dependency report TODO report (//TODO, FIXME, configurable) Linked and line-numbered HTML sources Release notes and roadmap from issue tracker
Quick Tour
In Brief (1)
Java EE support: WAR, EAR packaging Rapid web app development Integration (in container) testing Deployment to environments
Multi-module projects Enable / encourage reuse between projects Maven inter-module dependency eliminates cycles
between modules Nicely supported in NetBeans Not nicely supported in Eclipse – nested projects
In Brief (2)
Continuous Integration: CruiseControl Continuum
Reuses project information as defined in POM
Profiles Build activity carried out under different conditions,
e.g: personal requirements, dev / test / release, continuous integration
Maven settings
Help
Problems
History: Maven 1, might have left a bad taste Steep learning curve
Once you've got it, the knowledge is portable to other projects built with Maven
Complex needs require complex configuration Alan Kay: Simple things should be simple.
Complex things should be possible Verbose XML config Docs aren't great, but getting better Error messages often do not provide much (or any)
detail (e.g. archetype problem) Ensuring the project is buildable and testable in the
IDE as well as with Maven can be complex Multi-module projects not supported by Eclipse (but
they are in Netbeans)
Stuff to Look at
Buildr – a build system configured in Ruby that reuses parts of Maven: repositories; directory structure conventions;
Rake – a Ruby build tool
Still Interested?
Get reading and enjoy the ride
Questions?
Top Related