For the development of a Java Maven plugin, we will use the same tool chain we presented in Chapter 1, Maven and Its Philosophy.
Using Eclipse's utility, we can create a new project with Maven archetype. So, we obtain a skeleton for the new Maven plugin project. This is a good starting point for our project. Perform the following steps:
- First of all, we will create a new Eclipse project as a new Maven project from the menu, as shown in the following screenshot:
- Then, we can choose the location for our project and click on Next:
- Now, we have to select the artifact type for our project. First, we choose Nexus Indexer, then we select
maven-archetype-plugin, as shown in the following screenshot, and then click on Next:
- The last step in the creation procedure is the selection of the project's coordinates, as shown in the following screenshot:
The encouraged naming convention for artifactId is <ourplugin>-maven-plugin.
The archetype we chose during the creation phase created a pom.xml file with some dependencies imported by default:
maven-plugin-api: The articfact generation is set as default version 2.0. This is the basic library containing plugin utility classes.maven-plugin-annotation: This contains the annotation system. More details are available at http://maven.apache.org/plugin-tools/maven-plugin-tools-annotations/.maven-testing-plugin-harness: This is a library developed by Apache, for developing unit tests based on JUnit.junit: This is imported with the scope test for testing purposes.
The POM file generated by our IDE will also contain a build profile that is created for integration tests, named maven-invoker-plugin.
Before you start writing the plugin source code, we have to slightly edit the POM file that has been generated. First, we need to change the plexus-utils default dependency with maven-core. The second and last modification consists of aligning the version of maven-plugin-api with the version we chose for maven-core.
The result of our work is the following 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.example.mojo</groupId>
<artifactId>mantis-maven-plugin</artifactId>
<packaging>maven-plugin</packaging>
<version>0.0.1-SNAPSHOT</version>
<name>mantis-plugin Maven Mojo</name>
<url>http://maven.apache.org</url>
<properties>
<mavenVersion>3.2.1</mavenVersion>
</properties>
<dependencies>
<!-- Maven dependencies -->
<dependency>
<groupId>org.apache.maven</groupId>
<artifactId>maven-plugin-api</artifactId>
<version>${mavenVersion}</version>
</dependency>
<dependency>
<groupId>org.apache.maven</groupId>
<artifactId>maven-core</artifactId>
<version>${mavenVersion}</version>
</dependency>
<dependency>
<groupId>org.apache.maven.plugin-tools</groupId>
<artifactId>maven-plugin-annotations</artifactId>
<version>3.2</version>
<scope>provided</scope>
</dependency>
<!-- MySql driver -->
<dependency>
<groupId>mysql</groupId>
<artifactId>mysql-connector-java</artifactId>
<version>5.1.30</version>
</dependency>
<!-- Test dependencies -->
<!-- Mandatory in order to works with maven-plugin-testing- harness v. 3.1.0 -->
<dependency>
<groupId>org.apache.maven</groupId>
<artifactId>maven-compat</artifactId>
<version>3.2.1</version>
<scope>test</scope>
</dependency>
<dependency>
<groupId>org.apache.maven.plugin-testing</groupId>
<artifactId>maven-plugin-testing-harness</artifactId>
<version>3.1.0</version>
<scope>test</scope>
</dependency>
<dependency>
<groupId>junit</groupId>
<artifactId>junit</artifactId>
<version>3.8.1</version>
<scope>test</scope>
</dependency>
</dependencies>
<build>
<pluginManagement>
<plugins>
<plugin>
<groupId>
org.apache.maven.plugins
</groupId>
<artifactId>maven-plugin-plugin</artifactId>
<version>3.2</version>
<executions>
<execution>
<id>mojo-descriptor</id>
<goals>
<goal>descriptor</goal>
</goals>
</execution>
</executions>
<configuration>
<skipErrorNoDescriptorsFound>
true
<skipErrorNoDescriptorsFound>
</configuration>
</plugin>
</plugins>
</pluginManagement>
</build>
<profiles>
<profile>
<id>integration-tests</id>
<build>
<plugins>
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-invoker-plugin</artifactId>
<version>1.7</version>
<configuration>
<debug>true</debug>
<cloneProjectsTo>
${project.build.directory}/it
</cloneProjectsTo>
<pomIncludes>
<pomInclude>*/pom.xml</pomInclude>
</pomIncludes>
<postBuildHookScript>verify</postBuildHookScript>
<localRepositoryPath>
${project.build.directory}/local-repo
</localRepositoryPath>
<settingsFile>src/it/settings.xml</settingsFile>
<goals>
<goal>clean</goal>
<goal>test-compile</goal>
</goals>
</configuration>
<executions>
<execution>
<id>integration-test</id>
<goals>
<goal>install</goal>
<goal>integration-test</goal>
<goal>verify</goal>
</goals>
</execution>
</executions>
</plugin>
</plugins>
</build>
</profile>
</profiles>Tip
The maven-plugin-annotations dependency has the provided scope. Since annotations are not needed during plugin execution, this dependency can be excluded from the built package.
The maven-compat Version 3.2.1 is mandatory in order to make it possible to us the maven-plugin-testing-harness Version 3.1.0.
Once we perform a Maven update from our IDE, we can start to code the first Mojo.