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Groovy Eclipse Maven plugin
Groovy-Eclipse provides a compiler plugin for Maven. Using the compiler plugin, it is possible to compile your maven projects using the Groovy-Eclipse compiler.
How to use the compiler plugin - Setting up the POM
Complete POM examples can be found in the groovy-eclipse-compiler-tests project.
Many versions of the compiler plugins are available from Maven Central. To enable retrieval of the newest batch compiler and compiler artifacts, add a plugin repository for Groovy's Maven Bintray:
<pluginRepositories> <pluginRepository> <id>bintray</id> <name>Groovy Bintray</name> <url>https://dl.bintray.com/groovy/maven</url> <releases> <updatePolicy>never</updatePolicy> </releases> <snapshots> <enabled>false</enabled> </snapshots> </pluginRepository> ... </pluginRepositories>
In the build plugin section, 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
<build> ... <plugins> <plugin> <artifactId>maven-compiler-plugin</artifactId> <version>3.8.0</version><!-- 3.1 is the minimum --> <configuration> <compilerId>groovy-eclipse-compiler</compilerId> <compilerArguments> <indy/><!-- optional; supported by batch 2.4.12-04+ --> <configScript>config.groovy</configScript><!-- optional; supported by batch 2.4.13-02+ --> </compilerArguments> </configuration> <dependencies> <dependency> <groupId>org.codehaus.groovy</groupId> <artifactId>groovy-eclipse-compiler</artifactId> <version>3.0.0-01</version> </dependency> <dependency> <groupId>org.codehaus.groovy</groupId> <artifactId>groovy-eclipse-batch</artifactId> <version>2.5.3-01</version> </dependency> </dependencies> </plugin> </plugins> ... </build>
This will allow Groovy files to be compiled. The
groovy-eclipse-compiler recognizes all settings supported by the maven-compiler-plugin.
Remember that you still need to specify a groovy artifact as a build dependency in addition to the
maven-compiler-plugin dependency. The groovy dependency version should match the compiler version. Something like this:
<dependencies> ... <dependency> <groupId>org.codehaus.groovy</groupId> <artifactId>groovy</artifactId> <classifier>indy</classifier> <version>2.5.3</version> </dependency> ... </dependencies>
Setting up the source folders
There are several ways to set up your maven project to recognize Groovy source files
The simplest way to set up your source folders is to do nothing at all: add all of your Groovy files to
src/test/java. This requires absolutely no extra configuration and is easy to implement. However, this is not a standard maven approach to setting up your project. If you require a more standard maven approach, then it is possible to put your Groovy files in
src/test/groovy and you Java files in
src/test/java. There are several ways of doing this.
Do almost nothing
If there is at least one file (Java or not) in
src/main/java, then all files in
src/main/groovy will be found. If, however,
src/main/java is empty, then
src/main/groovy will be ignored. You can get around this by placing an empty file in
src/main/java just so that
src/main/groovy will be recognized. The same is true for
groovy-eclipse-compiler mojo for configuring source folders
(You only need this approach if your project has an empty
If your project has no Java files and you don’t want to add an empty file in
src/main/java, then you can configure source files by referencing the
groovy-eclipse-compiler mojo. Just add this to the
plugins section of your pom:
<build> ... <plugin> <groupId>org.codehaus.groovy</groupId> <artifactId>groovy-eclipse-compiler</artifactId> <version>3.0.0-01</version> <extensions>true</extensions> </plugin> ... </build>
<extensions>true</extensions> section is important because this redefines the default lifecycle of your project so that an extra phase is added. This phase has an extra goal attached to it that adds the two Groovy source folders.
(You only need this approach if your project has an empty
build-helper-maven-plugin allows you to do things like adding extra source folders to your project without needing to redefine the default lifecycle. You need to add this configuration to your build plugin section:
<build> ... <plugin> <groupId>org.codehaus.mojo</groupId> <artifactId>build-helper-maven-plugin</artifactId> <version>1.12</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>
The benefit of using this approach is that you do not need to make any changes to the default lifecycle. The downside is, of course, that you need 31 lines of configuration to do this!
Why another Groovy compiler for Maven? What about GMaven?
GMaven 2.0 and later no longer supports compilation. You can read more about this on the GMaven 2 project page. GMaven 1.x is now deprecated.
GMaven 1.x had limitations over the
groovy-eclipse-compiler and for the following reasons GMaven 2.0 compilation is no longer supported:
- 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.
- The Groovy-Eclipse compiler is the same inside Eclipse and inside Maven, and so configuration across the two platforms can be simplified.
- 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 still some reasons to use GMaven or GMavenPlus:
- GroovyDoc tool is not supported because the compiler plugin does not produce stubs.
- Groovy Mojos are not supported.
- Groovy scripts cannot be executed in your POMs.
InvokeDynamic is not supported.As of 2.4.12-04 indy is supported.
- Groovy Android is not supported.
Configuration scripts are not supported.As of 2.4.13-02 config scripts are supported.
- Interactive shell/console 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 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:
<dependency> <groupId>org.projectlombok</groupId> <artifactId>lombok</artifactId> <version>1.16.20</version> </dependency>
Also, the following configuration needs to be added to the
<configuration> <compilerId>groovy-eclipse-compiler</compilerId> <verbose>true</verbose> <compilerArguments> <!-- consult Lombok docs to confirm agent class name for your version --> <javaAgentClass>lombok.launch.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.
The Groovy-Eclipse configurator for m2eclipse is not compatible with AspectJ or Scala. So you cannot use a joint AspectJ/Scala/Groovy project in Eclipse. These languages must be separated into separate sub-projects.