Apache Maven

Apache Maven
Developer	Apache Software Foundation
Latest release	2.0.8 / November 27, 2007
OS	Cross-platform
Genre	Build Tool
License	Apache 2.0 licence
Website	maven.apache.org

For other uses of the word Maven see: Maven (disambiguation)

Maven is a software tool for Java programming language project management and automation created by Jason van Zyl in 2002. It is similar in functionality to the Apache Ant tool (and to a lesser extent, PHP's PEAR and Perl's CPAN), but has a simpler build configuration model, based on an XML format. Maven is hosted by the Apache Software Foundation, where it was formerly part of the Jakarta Project. Maven uses a construct known as a Project Object Model (POM) to describe the software project being built, its dependencies on other external modules and components, and the build order. It comes with pre-defined targets for performing certain well defined tasks such as compilation of code and its packaging. A key feature of Maven is that it is network-ready. The core engine can dynamically download plug-ins from a repository, the same repository that provides access to many versions of different Open Source Java projects, from Apache and other organisations and developers. This repository and its reorganized successor, the Maven 2 repository, strives to be the de facto distribution mechanism for Java applications, but its adoption has been slow. Maven provides built in support not just for retrieving files from this repository, but to upload artifacts at the end of the build. A local cache of downloaded artifacts acts as the primary means of synchronizing the output of projects on a local system.

Contents 1 Theory 1.1 Reuse 1.2 Life cycle 1.3 The POM 1.4 Assembly descriptor 2 Commands 2.1 Project creation 2.1.1 Component creation 2.1.2 Module (Multi module project) 2.2 Compilation 2.3 Testing 2.3.1 Running JUnit 3.8 test 2.3.2 Running JUnit 4 tests 2.4 Jar creation 2.5 Local installation 2.6 Creating an assembly 2.7 Project Information 2.8 Maven Plugins Configuration 2.8.1 javadoc 2.8.1.1 Adding overview file 2.8.1.2 Adding images 2.9 Java 5 compliance 3 See also 4 External links

Theory

Reuse

The whole idea of Maven is reuse - reuse of build logic. The general idea is that we build our projects the same way all the time, so why shouldn't we reuse the way we build them? The main idea is not to reuse the code or functionality (like Apache Ant), but to simply change the configuration of already written code. That's the main difference between Apache Ant and Apache Maven: one is a library of good and useful utilities and functions, while the other is a configurable and highly pluggable framework. Maven is a highly configurable framework, but the main idea is to change as little as possible, to stay with the defaults, so everything will work out of the box.

Life cycle

The parts of the main Maven project life cycle are: compile, test, package, install, deploy The idea is that, for any goal, all previous goals have already been successfully accomplished. For example, when you run mvn install Maven will check if mvn package has successfully been run (the jar exists in target/), in which case it will not be run again. Also, there are some goals that are outside the life cycle that can be called, but Maven assumes that these goals are not part of the default life-cycle (don't have to be always performed). These goals are: assembly:assembly, site, site-deploy, etc. But these goals can be added to the default life cycle through the project's POM.

The POM

• Introduction
• Simple examples and Super POM
• Schema
• Schema explanation
• POM Reference

Assembly descriptor

• Assembly descriptor

Commands

Project creation

Component creation

In order to create a maven project all one has to do is mvn archetype:create -DgroupId="com.your.company" -DartifactId="your-project" -Dversion="0.0.1"

• Plugins-site

Module (Multi module project)

You do the same thing as with the component, but you do it in the directory of the father POM and you change the father's POM <packaging>jar</packaging> to <packaging>pom</packaging>

Compilation

In order to compile the source files (default in src/main/java/*) mvn compile The files are compiled and put to target/classes.

Testing

Running JUnit 3.8 test

In order to run unit tests (default in src/test/java/*). mvn test The unit tests are compiled , put to target/test-classes, the unit tests are run and the test reports put in target/surefire-reports/ .

Running JUnit 4 tests

For now you must add:

<build>
  <plugins>
    <plugin>
      <artifactId>maven-surefire-plugin</artifactId>
      <version>2.3</version>
    </plugin>
  </plugins>
</build>

Jar creation

Creates a jar (default name ${artifactId}-${version}.jar) mvn package and puts it in target/

Local installation

Puts the created jar in local ~/.m2/repository/${groupId}/${artifactId}/${version} so different projects on the same computer can use it. mvn install

Creating an assembly

Assembly is a package given to a customer/QC engineer, configured through the assembly descriptor Creates an assembly and puts it in target mvn assembly:assembly

Project Information

In order to check exactly what definitions you use: mvn projecthelp:effective-pom mvn projecthelp:effective-settings

Maven Plugins Configuration

javadoc

Adding overview file

Add this to the POM:

 
 <reporting>
   <plugins>
     <plugin>
       <groupId>org.apache.maven.plugins</groupId>
       <artifactId>maven-javadoc-plugin</artifactId>
       <configuration>
         <overview>${basedir}/src/main/javadoc/overview.html</overview>
       </configuration>
     </plugin>
   </plugins>
 </reporting>
 

Adding images

In order to add images , for example in your overview file , you must put them in ${basedir}/src/main/javadoc/doc-files and put them in the HTML using relative path: <img src=doc-files/my-image.jpg />

Java 5 compliance

In order to have your project working on Java 5 - source and binary compliance add the following to your POM:

 <build>
    <plugins>
       <plugin>
          <groupId>org.apache.maven.plugins</groupId>
          <artifactId>maven-compiler-plugin</artifactId>
          <configuration>
             <source>1.5</source>
             <target>1.5</target>
        </configuration>
     </plugin>
   </plugins>
  </build>

See also

• Apache Continuum, a continuous integration server which integrates tightly with Maven

External links

• Maven 1.x Home Page
• Maven 2 Home Page
• Maven plugins
• Maven 2 codehaus tutorial
• Maven 2 tutorial on java.net
• Free Maven2 Book
• Free Maven2 Book
• Maven Training from Sonatype

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License: Apache License · Website: http://apache.org/