Groovy-Eclipse compiler plugin for Maven

How to use the compiler plugin---Setting up the POM

In your plugin section,you must change the compiler used by the maven-compiler-plugin. Like the javac ant task,the maven-compiler-plugin does not actually compile,but rather delegates the compilation to a different artifact (in our case,the groovy-eclipse-batch artifact):

t;build>
...
<plugins>
  <plugin>
    <artifactId>maven-compiler-plugin</artifactId>
    <version>2.3.2</version>
    <configuration>
      <compilerId>groovy-eclipse-compiler</compilerId>
      <verbose>true</verbose>
    </configuration>
    <dependencies>
      <dependency>
        <groupId>org.codehaus.groovy</groupId>
        <artifactId>groovy-eclipse-compiler</artifactId>
        <version>2.6.0-01</version>
      </dependency>
    </dependencies>
  </plugin>
  ...
</plugins>
</build>

By default,this will use Groovy 1.8.4 to compile your code. If you would prefer to use 1.7.10,then add another dependency to the maven-compiler-plugin:

t;dependency>
  <groupId>org.codehaus.groovy</groupId>
  <artifactId>groovy-eclipse-batch</artifactId>
  <version>1.7.10-06</version>
</dependency>

This will allow Groovy files to be compiled. The groovy-eclipse-compiler recognizes all settings supported by the maven-compiler-plugin.

Note that the groovy-eclipse-compiler and groovy-eclipse-batch artifacts are available in Maven-central,so there is no need to explicitly declare any extra repositories.

Setting up the source folders

There are several ways to set up your maven project to recognize Groovy source files

t;build>
  ...
  <plugin>
    <groupId>org.codehaus.groovy</groupId>
    <artifactId>groovy-eclipse-compiler</artifactId>
    <version>2.6.0-01-SNAPSHOT</version>
    <extensions>true</extensions>
  </plugin>
  ...
</build>

t;build>
  ...
  <plugin>
    <groupId>org.codehaus.mojo</groupId>
    <artifactId>build-helper-maven-plugin</artifactId>
    <version>1.5</version>
    <executions>
      <execution>
        <id>add-source</id>
        <phase>generate-sources</phase>
        <goals>
          <goal>add-source</goal>
        </goals>
        <configuration>
          <sources>
            <source>src/main/groovy</source>
          </sources> 
        </configuration>
      </execution>
      <execution>
        <id>add-test-source</id>
        <phase>generate-test-sources</phase>
        <goals>
          <goal>add-test-source</goal>
        </goals>
        <configuration>
          <sources>
            <source>src/test/groovy</source>
          </sources>
        </configuration>
      </execution>    
    </executions>
  </plugin>
  ...
</build>

Sample project and source code

There is an archetype available for this project. You can use it through a command like this:

n archetype:generate 
    -DarchetypeGroupId=org.codehaus.groovy 
    -DarchetypeArtifactId=groovy-eclipse-quickstart 
    -DarchetypeVersion=2.5.2-01 
    -DgroupId=foo 
    -DartifactId=bar 
    -Dversion=1 
    -DinteractiveMode=false 
    -DarchetypeRepository=https://nexus.codehaus.org/content/repositories/snapshots/

A sample project using the compiler plugin as well as the source code for the plugin itself are available from the Codehaus.org subversion repository:

The sample project and archetype is not maintained as well as we would like. Some community help with this would be greatly appreciated. Please see GRECLIPSE-1285.

Why another Groovy compiler for Maven? What about GMaven?

There are several benefits that the compiler plugin provides over GMaven,but at the same time it has a few limitations. First,the benefits:

1. The compiler plugin does not require the creation of Java stubs so that your Groovy files can compile against Java files. This will prevent some arcane compile errors from appearing.
2. The Groovy-Eclipse compiler is the same inside Eclipse and inside Maven,and so configuration across the two platforms can be simplified.
3. The compiler plugin is a standard compiler plugin for Maven. It therefore follows all allows all the same standard configuration that the Javac compiler plugin uses. This makes it simpler to introduce Groovy into an existing Maven project. All you need to do is change the compiler plugin that the pom references.

There are some limitations:

1. GroovyDoc tool is not supported because the compiler plugin does not produce stubs.
2. Groovy Mojos are not supported.
3. Groovy scripts cannot be executed in your poms.
4. Groovy compiler options are not passed through to the compiler.
5. The defaultScriptExtension compiler option is not supported.

Whether or not the Groovy-Eclipse compiler plugin for Maven is appropriate for your project will depend on your requirements.

Project Lombok

Project Lombok is compatible with the groovy-eclipse-compiler.? There is some extra configuration that you need to do.? The lombok jar needs to be added to both the build and compile dependencies sections:

t;dependency>
  <groupId>org.projectlombok</groupId>
  <artifactId>lombok</artifactId>
  <version>0.10.4</version>
</dependency>

Also,the following configuration needs to be added to the maven-compiler-plugin configuration:

t;configuration>
  <compilerId>groovy-eclipse-compiler</compilerId>
  <verbose>true</verbose>
  <compilerArguments>
    <javaAgentClass>lombok.core.Agent</javaAgentClass>
  </compilerArguments>
  <fork>true</fork>
</configuration>

Groovy-Eclipse configurator for m2Eclipse

If you are going to be working with your maven project inside of Eclipse,it is strongly recommended that you use m2eclipse. And to use your Groovy projects with m2eclipse,you will need to install the Groovy-Eclipse configurator for m2eclipse. This feature is available any of the Groovy-Eclipse update sites (e.g.,nightly,milestone,or release). Just go to your Eclipse update manager and add the Groovy-Eclipse update sites (if you haven't done so already). Select the Groovy-Eclipse M2E integration.

Release update site for Eclipse 3.7:

http://dist.springsource.org/release/GRECLIPSE/e3.7/

and 3.6:

http://dist.springsource.org/release/GRECLIPSE/e3.6/

Nightly update site for Eclipse 3.7:

http://dist.codehaus.org/groovy/distributions/greclipse/snapshot/e3.7/

and 3.6:

http://dist.codehaus.org/groovy/distributions/greclipse/snapshot/e3.6/