Following our target, create a XP Software Development Environment, today we add another tol for the box. Maven is a project management tool with the following main features:

• Convention over configuration: it provides many estructural standards for the project in order to make easy the development, and avoid problems with many configuration files:
  • ${basedir}/src/main/java: your code
  • ${basedir}/src/main/resources: configuration resources
  • ${basedir}/src/main/webapp: web, css, html, jsp ... files
  • ${basedir}/src/test: test classes
  • ${basedir}/target/classes: compiled classes
  • ${basedir}/target: jar, war, ear.... for packages
  • ....
• Manage all life cycle steps for the project:
  • Very simple Life Cycle: Compiling --> Test --> Packaging
  • In every life cycle steps you can execute goals. In packaging for example: mvn jar:jar
• Manage the dependencies with other projects, this is the feature that takes my attention:
  • Forget download jar libraries for spring, hibernate, configure them in Java Buil Path,..... bad stuff. Solution: write your dependencies in pom.xml, and it download them and makes the Build path.
  • The Archetypeeeees ¡¡¡¡ They are application skeletons with preconfigured pom.xml to develop projects like grails, seam, roo,... Take a look at Appfuse and this archetypes when you will create a project with maven in eclipse.
• Have a plugin ecosystem to execute goals for all the phases in every kind of project.

Furthermore in my case gives some fundamental features:

• Full Elcipse integration (M2Eclipse).
• Good documentation: Maven the Definitive Guide and m2eclipse Documentation.
• It integrates our projects easy with other XP tools like Continuous Integration, TDD, code analizers,...

Install with the following instructions:

• Download Maven in a folder in your system: c:\dev\frameworks\maven2
• define this folder in PATH as M2_HOME. You can test it: mvn -v
• Eclipse installation Help > Install New Software > Add http://m2eclipse.sonatype.org/update/

For the begining we are going to make an example with Eclipse. Create a new project File > New > Other ... > Maven > Maven Project. Mark "Create a simple project" to avoid archetypes now. Maven makes you fill Group Id, Artifact ID. Create the following example Class:

package com.lebrijo.ejemploMaven;public class Hello {public static void main( String[] args )    {

        System.out.println( "Hello World!" );

    }

}

The command "mvn install" generate the jar that we execute with "java -cp target/simple-1.0-SNAPSHOT.jar com.lebrijo.ejemploMaven.Hello". But in Eclipse you can execute as Java Application. To add a dependency, right button over the project > Maven > Add dependencies:

We could use the Spring dependency injection making the search, and select the concrete version. After thar we update the libraries with right clic over the project > Maven > Update Dependencies. This actiion generates the followin pom.xml file:

  	

  		org.springframework

  		spring-context

  		3.0.0.RELEASE

  	

Take the example project from the following link: Maven2 basic example.