Setting up Maven on Mac OS and Creating Java Project

This post shows how to setup Maven on Mac OS and how to create, build and run a new Maven Java project. Before continuing, make sure that a Java SDK 1.7 or greater is installed and that the Java commands are available in your PATH environment variable. In a terminal window, run the following command to confirm this:

java -version

MacBookPro:opt admin$ java -version
java version "1.8.0_77"
Java(TM) SE Runtime Environment (build 1.8.0_77-b03)
Java HotSpot(TM) 64-Bit Server VM (build 25.77-b03, mixed mode)
MacBookPro:opt admin$
 
  • For a related post on installing a Java SDK and setting up a Java EE development environment refer to the below post on this site:

Summary

  1. Installing and Configuring Maven on Mac OS
  2. Creating a Maven Java Project from an Archetype
  3. Adding Project Dependencies in the POM File

1  Installing and Configuring Maven on Mac OS

  • In this example, Maven 3.5 is used. It can be downloaded as a binary distribution from the Apache Maven Website. The operating system version used here is Mac OS Sierra (10.12.6).

Download Maven Binary Distribution from Apache Website to Install Maven on Mac OS

  • Unzip the Maven 3.5 files into some folder on the local disk. In this example, the Maven files are unzipped into the ${maven.home} folder at:
/opt/apache-maven-3.5.0

Maven Home Folder Contents

  • For instructions on how to add the Maven commands from the ${maven.home}\bin folder to the PATH environment variable on macOS see:
  • Open a terminal window and verify that maven is installed properly by executing the below command to view the Maven version:
mvn -version
  • The output should look like the example below, showing the Java version and Java home folder:

Last login: Wed Oct 11 01:07:07 on ttys000
MacBookPro:~ admin$ /opt/apache-maven-3.5.0/bin/mvn -version
Apache Maven 3.5.0 (ff8f5e7444045639af65f6095c62210b5713f426; 2017-04-03T15:39:06-04:00)
Maven home: /opt/apache-maven-3.5.0
Java version: 1.8.0_77, vendor: Oracle Corporation
Java home: /Library/Java/JavaVirtualMachines/jdk1.8.0_77.jdk/Contents/Home/jre
Default locale: en_US, platform encoding: UTF-8
OS name: "mac os x", version: "10.12.5", arch: "x86_64", family: "mac"
MacBookPro:~ admin$

  • If a proxy is needed to connect to the Internet, edit ${maven.home}/.m2/conf/settings.xml:
  <!-- proxies
   | This is a list of proxies which can be used on this machine to connect to the network.
   | Unless otherwise specified (by system property or command-line switch), the first proxy
   | specification in this list marked as active will be used.
   |-->
  <proxies>
    <!-- proxy
     | Specification for one proxy, to be used in connecting to the network.
     |-->
    <proxy>
      <id>optional</id>
      <active>true</active>
      <protocol>http</protocol>
      <username>domain\username</username>
      <password>password</password>
      <host>proxy.host.com</host>
      <port>80</port>
      <nonProxyHosts>local.net|some.host.com</nonProxyHosts>
    </proxy>
  </proxies>
  • When a Maven project is built, Maven will download all dependent artifacts (JAR files) from a remote repository to a local repository. By default, Maven will create the local repository in:
${user.home}/.m2/repository
  • The Maven local repository contains all downloaded artifacts and looks like the example below:

Default Maven Local Repository Location on macOS

  • To change the location of the local repository, edit ${maven.home}/.m2/conf/settings.xml:
  <!-- localRepository
   | The path to the local repository maven will use to store artifacts.
   | Default: ${user.home}/.m2/repository
   |-->
  <localRepository>/my/local/repository</localRepository>

2  Creating a Maven Java Project from an Archetype

  • To create a Maven Java project with JUnit support, using the archetype maven-archetype-quickstart, execute the command:
mvn archetype:generate -DgroupId=com.company.app -DartifactId=my-app 
    -DarchetypeArtifactId=maven-archetype-quickstart -DinteractiveMode=false
  • When Maven first downloads required dependencies to the local repository, the build may take a while.
  • The output should look like below and result in a BUILD SUCCESS message.
Downloading: https://repo.maven.apache.org/maven2/org/apache/maven/archetype/maven-archetype-parent/1/maven-archetype-parent-1.pom
Downloaded: https://repo.maven.apache.org/maven2/org/apache/maven/archetype/maven-archetype-parent/1/maven-archetype-parent-1.pom (1.3 kB at 8.7 kB/s)
Downloading: https://repo.maven.apache.org/maven2/org/apache/maven/maven-parent/4/maven-parent-4.pom
Downloaded: https://repo.maven.apache.org/maven2/org/apache/maven/maven-parent/4/maven-parent-4.pom (10.0 kB at 54 kB/s)
Downloading: https://repo.maven.apache.org/maven2/org/apache/maven/archetypes/maven-archetype-quickstart/1.0/maven-archetype-quickstart-1.0.jar
Downloaded: https://repo.maven.apache.org/maven2/org/apache/maven/archetypes/maven-archetype-quickstart/1.0/maven-archetype-quickstart-1.0.jar (4.3 kB at 28 kB/s)
[INFO] ----------------------------------------------------------------------------
[INFO] Using following parameters for creating project from Old (1.x) Archetype: maven-archetype-quickstart:1.0
[INFO] ----------------------------------------------------------------------------
[INFO] Parameter: basedir, Value: /Users/admin/Desktop/MyProjects/pegaxchange.com/posts/3506
[INFO] Parameter: package, Value: com.company.app
[INFO] Parameter: groupId, Value: com.company.app
[INFO] Parameter: artifactId, Value: my-app
[INFO] Parameter: packageName, Value: com.company.app
[INFO] Parameter: version, Value: 1.0-SNAPSHOT
[INFO] project created from Old (1.x) Archetype in dir: /Users/admin/Desktop/MyProjects/pegaxchange.com/posts/3506/my-app
[INFO] ------------------------------------------------------------------------
[INFO] BUILD SUCCESS
[INFO] ------------------------------------------------------------------------
[INFO] Total time: 2.639 s
[INFO] Finished at: 2017-10-18T18:07:10-04:00
[INFO] Final Memory: 19M/308M
[INFO] ------------------------------------------------------------------------
MacBookPro:3506 admin$ 
  • Maven will create a folder using the artifactId and create the standard project structure based on the groupId:
my-app
|-- pom.xml
`-- src
    |-- main
    |   `-- java
    |       `-- com
    |           `-- company
    |               `-- app
    |                   `-- App.java
    `-- test
        `-- java
            `-- com
                `-- company
                    `-- app
                        `-- AppTest.java
  • The root folder of the Maven project contains a POM file (Project Object Model). Here, the file contains:
<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/maven-v4_0_0.xsd">

    <modelVersion>4.0.0</modelVersion>
    <groupId>com.company.app</groupId>
    <artifactId>my-app</artifactId>
    <packaging>jar</packaging>
    <version>1.0-SNAPSHOT</version>
    <name>my-app</name>

    <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>
  • To compile and package the Java project, execute in the project root folder (containing the pom.xml file):
mvn clean compile package
[INFO] Compiling 1 source file to /Users/admin/my-app/target/test-classes
[INFO] 
[INFO] --- maven-surefire-plugin:2.12.4:test (default-test) @ my-app ---
[INFO] Surefire report directory: /Users/admin/my-app/target/surefire-reports

-------------------------------------------------------
 T E S T S
-------------------------------------------------------
Running com.company.app.AppTest
Tests run: 1, Failures: 0, Errors: 0, Skipped: 0, Time elapsed: 0.005 sec

Results :

Tests run: 1, Failures: 0, Errors: 0, Skipped: 0

[INFO] 
[INFO] --- maven-jar-plugin:2.4:jar (default-jar) @ my-app ---
[INFO] Building jar: /Users/admin/my-app/target/my-app-1.0-SNAPSHOT.jar
[INFO] ------------------------------------------------------------------------
[INFO] BUILD SUCCESS
[INFO] ------------------------------------------------------------------------
[INFO] Total time: 2.568 s
[INFO] Finished at: 2017-10-18T19:12:04-04:00
[INFO] Final Memory: 16M/186M
[INFO] ------------------------------------------------------------------------
MacBookPro:my-app admin$
  • The resulting JAR file is located in the target folder of the project:

Maven Java Standard Project Structure

  • It can be executed from the project folder with the java command:
java -cp target/my-app-1.0-SNAPSHOT.jar com.company.app.App
  • Which will produce the below output:
MacBookPro:my-app admin$ java -cp target/my-app-1.0-SNAPSHOT.jar com.company.app.App
Hello World!
MacBookPro:my-app admin$ 
  • As per the App.java source file:
package com.company.app;

public class App {

    public static void main( String[] args ) {
        System.out.println( "Hello World!" );
    }
}

3  Adding Project Dependencies in the POM File

  • The Maven Central Repository is used to find and add dependencies to a project’s POM file.
  • For example, to add support for JSON processing to the project, Google’s GSON API can be used.
  • Search for "GSON" in the Maven Central Repository to find the Maven dependency information.

Maven Central Repository - Search for Artifact

  • Click on the version link, here 2.8.2, to view the dependency information:

Maven Central Repository - GSON 2.8.2 Artifact Details

  • Copy and paste the dependency information from the Apache Maven section into the project’s 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/maven-v4_0_0.xsd">

    <modelVersion>4.0.0</modelVersion>
    <groupId>com.company.app</groupId>
    <artifactId>my-app</artifactId>
    <packaging>jar</packaging>
    <version>1.0-SNAPSHOT</version>
    <name>my-app</name>

    <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>
        <!-- Support for JSON Processing -->
        <dependency>
            <groupId>com.google.code.gson</groupId>
            <artifactId>gson</artifactId>
            <version>2.8.2</version>
        </dependency>
    </dependencies>
</project>
  • The scope of the new dependency is not specified. It is compile by default. See Dependency Scope for more information.
  • The GSON API can now be used in the App.java source file to serialize Java objects:
package com.company.app;

import com.google.gson.Gson;

public class App {

    public static void main( String[] args ) {
        Car car = new App().new Car();
        car.setMake("BMW");
        car.setModel("335i");

        System.out.println(new Gson().toJson(car));
    }

    class Car {

        private String make;
        private String model;

        public String getMake() {
            return make;
        }

        public void setMake(String make) {
            this.make = make;
        }

        public void setModel(String model) {
            this.model = model;
        }

        public String getModel() {
            return model;
        }
    }
}

4  Execute the Java Application with the Maven exec Plugin

  • Maven can be used to compile and then execute the App class using the exec plugin:
mvn compile exec:java -Dexec.mainClass="com.company.app.App"
  • The output will be a JSON representation of the Car object:
[INFO] --- maven-compiler-plugin:3.1:compile (default-compile) @ my-app ---
[INFO] Changes detected - recompiling the module!
[INFO] Compiling 1 source file to /Users/admin/my-app/target/classes
[INFO] 
[INFO] --- exec-maven-plugin:1.6.0:java (default-cli) @ my-app ---
{"make":"BMW","model":"335i"}
[INFO] ------------------------------------------------------------------------
[INFO] BUILD SUCCESS
[INFO] ------------------------------------------------------------------------
[INFO] Total time: 1.421 s
[INFO] Finished at: 2017-10-19T12:52:29-04:00
[INFO] Final Memory: 18M/301M
[INFO] ------------------------------------------------------------------------
{"make":"BMW","model":"335i"}

Leave a Reply