Maven on MacOS (OSX)

for Java, Jenkins, etc.

Overview

Mated with Java
Default in Jenkins
Install latest
- Install previous version
Configure Path
Change Default Configurations
Using Maven
Mirror
Build Profiles
References
More on OSX

This describes how to install Maven using Homebrew, the configure and use it.

Maven is a task runnner, like Ant, Gradle, Grunt.

Ant was originally created (using Java) to replace the make utility for cross-platform use. With Ant, everything needs to be coded explictly in XML. Its files are difficult to reuse.

Unlike Ant, Maven also provides dependency management, standard project layout, and project management.

Mated with Java

Maven is written in Java, and grew up supporting Java builds by creating from Java source and resources for deployment deliverables like JAR file or WAR files.

Default in Jenkins

Maven is the default build tool in the Jenkins continuous integration tool to perform builds when code is committed.

Unlike shell script procedural code, Maven files enable declarative statements.

Maven adopts the principle of “Convention over configuration”, which means less coding work. However, it operates as a “black box”.

Install latest

PROTIP: Rather than downloading directly from https://maven.apache.org/download.cgi, use a package manager.

To install the latest version on MacOS:

brew install maven

the response I got on Dec 29, 2017:

==> Downloading https://www.apache.org/dyn/closer.cgi?path=maven/maven-3/3.5.2/binaries/apache-maven-3.5.2-bin.tar.gz
==> Best Mirror http://apache.mirrors.lucidnetworks.net/maven/maven-3/3.5.2/binaries/apache-maven-3.5.2-bin.tar.gz
######################################################################## 100.0%
🍺  /usr/local/Cellar/maven/3.5.2: 104 files, 10.1MB, built in 21 seconds

Install previous version

Alternately, to install a previous version:

brew install homebrew/versions/maven30

Then, to switch among versions:

brew unlink maven30 && brew link maven
brew unlink maven && brew link maven30

Configure Path

Verify install:


mvn -version

I got this response:

Apache Maven 3.5.2 (138edd61fd100ec658bfa2d307c43b76940a5d7d; 2017-10-18T03:58:13-04:00)
Maven home: /usr/local/Cellar/maven/3.5.2/libexec
Java version: 1.8.0_25, vendor: Oracle Corporation
Java home: /Library/Java/JavaVirtualMachines/jdk1.8.0_25.jdk/Contents/Home/jre
Default locale: en_US, platform encoding: UTF-8
OS name: "mac os x", version: "10.11.6", arch: "x86_64", family: "mac"

Confirm the path:
```
which mvn
```
response:
```
/usr/local/bin/mvn
```
NOTE: Before OSX Mavericks, Maven was installed by default in:
/usr/share/maven/bin/mvn
Confirm the path. Substitute the version (3.5.2) with the version you just installed:
```
cd /usr/local/Cellar/maven/3.5.2/libexec
cd bin
ls
```
mvn files should be listed:
```
m2.conf     mvn      mvnDebug mvnyjp
```
Open using a text editor, substituting subl (for Sublime) with atom or vim:
```
cd $HOME
subl .bash_profile
```
Add the following to under export PATH=, changing the version (3.5.2) to whatever appears above:
```
export M2_HOME=/usr/local/Cellar/maven/3.5.2/libexec
export M2=$M2_HOME/bin
export PATH=$PATH:$M2_HOME/bin
```
On Windows, define environment variable M2_HOME with a path such as:
```
C:\apache-maven-3.3.3
```
Within environment variable PATH, add:
```
%M2_HOME%\bin;
```
View changed environment variables. On a Mac:
```
echo $M2_HOME
```
The response if installed by Homebrew on Mac:
/usr/local/Cellar/maven/3.5.2/libexec
```
echo $M2
```
The response if installed by Homebrew on Mac:
/usr/local/Cellar/maven/3.5.2/libexec/bin
```
echo $PATH
```
On Windows:
```
echo $M2_HOME
echo $M2
echo $PATH
```

In a Terminal, verify changes:

echo $JAVA_HOME

The reply is, for example:

/Library/Java/JavaVirtualMachines/jdk1.7.0_65.jdk/Contents/Home

Change Default Configurations

Navigate to the hidden folder Maven installed to house packages installed (junit, commons-cli, commons-lang, etc).
```
cd ~/.m2/repository
```
Some prefer to change Maven’s local repository to another location.

See https://maven.apache.org/guides/mini/guide-configuring-maven.html

There is a settings.xml file containing:
```
<localRepository>~//maven/repo/</localRepository>
```

Using Maven

Maven allows use of a central maven repository.

The pom.xml (Project Object Model) file describes project dependencies which Maven resolves by downloading them.

NOTE: Some prefer to install and use the Cargo plugin (from Codehaus) to Maven in order to eliminate use of pom.xml. In a folder that contains a pom.xml:

mvn clean verify org.codehaus.cargo:cargo-maven2-plugin:run

https://codehaus-cargo.atlassian.net/wiki/spaces/CARGO/pages/491622/Maven2+Plugin+Reference+Guide

The vast majority of Maven-built projects can be built with this command:

mvn clean install

The “clean” cleans out results from the prior build before starting with install.

During the first full run, testing jars are installed in your local maven repository.

[INFO] ------------------------------------------------------------------------
[INFO] BUILD SUCCESS
[INFO] ------------------------------------------------------------------------
[INFO] Total time: 26.549 s
[INFO] Finished at: 2018-02-15T09:55:56-05:00
[INFO] Final Memory: 86M/639M
[INFO] ------------------------------------------------------------------------

Maven is said to also act as project management tool because it can generate reports etc.

build.xml

Maven enforces a standard naming convention for artifacts defined using groupId, artifactId, and version.
After the first run, builds can skip tests with this additional parameter:
```
mvn clean install -Dmaven.test.skip=true
```

Maven lifecycle phases

Here are sub-commands for mvn:

Default Lifecycle:

Sub-command	Description
validate	Validate the project is correct and all necessary information is available
initialize	initialize build state, (for example : set properties, create directories,… etc)
generate-sources	generate any source code for inclusion in compilation
process-sources	process the source code (for example : filter any values)
generate-resources	generate resources for inclusion in the package.
process-resources	copy and process the resources into the destination directory, ready for packaging.
compile	compile the source code of the project.
process-classes	post-process the generated files from compilation (for example : to do bytecode enhancement on Java classes)
generate-test-sources	generate any test source code for inclusion in compilation.
process-test-sources	process the test source code (for example : to filter any values)
generate-test-resources	create resources for testing.
process-test-resources	copy and process the resources into the test destination directory.
test-compile	compile the test source code into the test destination directory.
process-test-classes	post-process the generated files from test compilation (for example : to do bytecode enhancement on Java classes)
test	run tests using a suitable unit testing framework. These tests should not require the code be packaged or deployed.
prepare-package	perform any operations necessary to prepare a package before the actual packaging. This often results in an unpacked, processed version of the package.
package	Take the compiled code and package it in its distributable format (for example : jar, war, …etc)
pre-integration-test	perform actions required before integration tests are executed. This may involve things such as setting up the required environment.
integration-test	process and deploy the package if necessary into an environment where integration tests can be run.
post-integration-test	perform actions required after integration tests have been executed. This may including cleaning up the environment.
verify	run any checks to verify the package is valid and meets quality criteria.
install	install the package into the local repository, for use as a dependency in other projects locally.
deploy	done in an integration or release environment, copies the final package to the remote repository for sharing with other developers and projects.

Clean Lifecycle:

Sub-command	Description
pre-clean	Executes processes needed prior to the actual project cleaning
clean	Remove all files generated by the previous build
post-clean	Execute processes needed to finalize the project cleaning

Site Lifecycle:

Sub-command	Description
pre-site	Executes processes needed prior to the actual project site generation.
site	Generates the project’s site documentation.
post-site	Executes processes needed to finalize the site generation, and to prepare for site deployment.
site-deploy	Deploys the generated site documentation to the specified web server.

See

http://maven.apache.org/guides/introduction/introduction-to-the-lifecycle.html#Lifecycle_Reference
http://books.sonatype.com/mvnref-book/reference/lifecycle-sect-common-goals.html

Maven plug-in goals by lifecycle phase

Each unit of execution work in Maven is called a goal.

Maven C/C++ Plugin http://duns.github.io/maven-nar-plugin/

Maven plug-ins by lifecycle phase

The graphic at Empeccableweb includes “Archetype”:

maven2-100156414-orig

Dependencies

http://www.sonatype.com/resources/books/maven-by-example
https://books.sonatype.com/mvnref-book/reference/pom-relationships-sect-pom-best-practice.html
http://www.sonatype.com/resources/books/maven-the-complete-reference

Mirror

See https://maven.apache.org/guides/mini/guide-mirror-settings.html

The Maven Central Repository provides a UI to
the mirror website where Maven pulls files from. In the US it is:

http://repo.maven.apache.org/maven2

The UK mirror supports Europe:

http://uk.maven.org/maven2

Others:
http://repo.maven.apache.org/maven2/.meta/repository-metadata.xml

Build Profiles

http://maven.apache.org/guides/introduction/introduction-to-profiles.html

References

http://www.mkyong.com/tutorials/maven-tutorials/ is a compelling resource.

More on OSX

This is one of a series on Mac OSX:

Wilson Mar