Maven

My 5 minute Maven startup

• Set M2_HOME env varibale and set maven\bin into the path.
• mvn —version
• A simple maven goal: mvn archetype:create -DgroupId=com.mycompany.app -DartifactId=my-app
• In the command "mvn archtype:create", archtype is a plugin and create is a goal. a plugin is a collection of goals with a general common purpose
• artifactId This element indicates the unique base name of the primary artifact being generated by this project. The primary artifact for a project is typically a JAR file. Secondary artifacts like source bundles also use the artifactId as part of their final name. A typical artifact produced by Maven would have the form <artifactId>-<version>.<extension> (for example, myapp-1.0.jar).
• To build a project : mvn package. Package is a phase in the life cycle (validate,compile,test,package,integration-test,verify,install,deploy,clean,site,…). Maven will execute every phase in the sequence up to and including the one defined. Do this inside my-app directory
• Phases are actually mapped to underlying goals
• Running the simple app: java -cp target/my-app-1.0-SNAPSHOT.jar com.mycompany.app.App
• mvn clean dependency:copy-dependencies package : This command will clean the project, copy dependencies, and package the project (executing all phases up to package, of course).
• mvn clean : This will remove the target directory with all the build data before starting so that it is fresh.
• mvn eclipse:eclipse : This can be run on a normal maven project and will make eclipse config files so that you can easily import it to eclipse. Make sure you have M2_REPO defined in your eclipse. Even if you see it as a library prefix but still you need to define it as a classpath variable.
• mvn site : creates a site with project information under /target!
• POM = Project Object Model

Definitions and Points

• two main directory layouts for Maven are /src/main/ and /src/test/
• A goal not bound to any build phase could be executed outside of the build lifecycle by direct invocation. The clean and package arguments are build phases while the dependency:copy-dependencies is a goal: mvn clean dependency:copy-dependencies package
• List of plugins : http://maven.apache.org/plugins/

How to add a library dependency

Look for the library metadata in http://repo1.maven.org/maven2/ and add it as following to your pom:

<dependency>
        <groupId>log4j</groupId>
        <artifactId>log4j</artifactId>
        <version>1.2.12</version>
        <scope>compile</scope>
    </dependency>

Simple web application

mvn archetype:create -DarchetypeGroupId=org.apache.maven.archetypes -DarchetypeArtifactId=maven-archetype-webapp -DgroupId=com.mycompany.app -DartifactId=my-webapp

dependency to another eclipse project

If you need to use another eclipse project in your project it is a form of dependency as well.

<dependency>
      <groupId>com.notes.common</groupId>
      <artifactId>common</artifactId>
      <version>1.0-SNAPSHOT</version>
    </dependency>

Putting this in our pom.xml we are using project "common". In eclipse it will go under required projects in build path.