An Introduction

To Maven

Deven Phillips

Senior Software Engineer

Sungard Availability Services

What Is Maven?

A build automation tool used primarily for Java projects. The word maven means 'accumulator of knowledge' in Yiddish. Maven addresses two aspects of building software: First, it describes how software is built, and second, it describes its dependencies.

- Wikipedia

Compiling Java Projects

Classpath Hell
Applying Compiler Plugins
Managing Dependencies/JARs
Project Validation
Running Tests
Validation
Reporting
Continuous Integration

Makefiles

Not Designed For Java
Difficult To Maintain
Doesn't Do Dependency Management
No Artifact Publishing

Apache Ant

Doesn't Do Dependency Management
Requires Lots Of Manual Integration
Still Leads To Classpath Problems
No Artifact Publishing

Apache Ivy

Just Ant With Dependency Management
Has Artifact Publishing

Why Maven?

Simple To Use
Widespread IDE Support
Extensible With Hundreds Of Plugins
Manages Dependencies Simply
Handles Nested Child Projects

How Do I Use Maven?

Install Maven from https://maven.apache.org

Create a new Maven project

mvn archetype:create 
  -DgroupId=[your project's group id]
  -DartifactId=[your project's artifact id]
  -DarchetypeArtifactId=maven-archetype-quickstart

A Simple Maven Project

<project root>/pom.xml
              /src
                  /main
                       /java/<package>/*.java
                       /resources/
              /target/<package>/*.class

Basic Maven Commands

```
mvn compile
```
```
mvn site
```
```
mvn clean
```
```
mvn package
```
```
mvn publish
```
```
mvn test
```

The POM File

<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/xsd/maven-4.0.0.xsd">
  <modelVersion>4.0.0</modelVersion>

  <groupId>com.zanclus</groupId>
  <artifactId>my-app</artifactId>
  <version>1.0-SNAPSHOT</version>
  <packaging>jar</packaging>

  <name>my-app</name>
  <url>http://maven.apache.org</url>

  <properties>
    <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
  </properties>

  <dependencies>
    <dependency>
      <groupId>junit</groupId>
      <artifactId>junit</artifactId>
      <version>3.8.1</version>
      <scope>test</scope>
    </dependency>
  </dependencies>
</project>

Adding Dependencies

  <dependencies>
    <dependency>
      <groupId>org.eclipse.jetty</groupId>
      <artifactId>jetty-servlet</artifactId>
      <version>9.3.2.v20150730</version>
      <scope>compile</scope>
    </dependency>

    <dependency>
      <groupId>junit</groupId>
      <artifactId>junit</artifactId>
      <version>3.8.1</version>
      <scope>test</scope>
    </dependency>
  </dependencies>

Controlling The Build

<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/xsd/maven-4.0.0.xsd">
  <modelVersion>4.0.0</modelVersion>

... 

  <build>
    <plugins>
      <plugin>
        <groupId>org.apache.maven.plugins</groupId>
        <artifactId>maven-compiler-plugin</artifactId>
        <version>3.3</version>
        <configuration>
          <source>1.8</source>
          <target>1.8</target>
        </configuration>
      </plugin>
    </plugins>
  </build>

...
  
</project>

MojoHaus (Formerly CodeHaus)

Useful Plugins

SureFire - Run And Report On Unit Tests
PMD - Static Code Analysis
Eclipse - Generate Eclipse .project from POM
Jetty - Run a web application from an embedded Jetty server
Cobertura - Code Coverage Reports
findbugs - More Static Code Analysis
license - Inserts/Verifies License Headers & Files
exec - Execute Commands/Java Applications

Let's Use It!

Code will be available at:

https://github.com/JUGGL/intro-to-maven