Maven plugin metadata extractor for plugins written in Kotlin.
This project is still a little new, so please help by reporting any issues you find.
The Java5 annotation metadata extractor partially works for Kotlin files. It's able to pull all the information from the annotations; the problem is the descriptions, deprecation messages and since version information, is still extracted from the JavaDoc, and this doesn't work for Kotlin files; the generated web site and the command line help are far less useful without descriptions.
This project provides a Kotlin metadata extractor using the Kotlin compiler to
give the same support for Kotlin files, as the Java5 annotation extractor does
for Java files (including support for descriptions and since version
information from KDoc, and deprecation messages from @kotlin.Deprecated).
Writing a Maven plugin in Kotlin (using this extractor) is much the same as it
normally is in Java; you extend org.apache.maven.plugin.AbstractMojo, annotate
the class and properties, and add descriptions in API code comments. However as
Kotlin has nullability constraints in the type system, you need to declare
whether properties can be null or not; you can use lateinit for the non-null
properties.
It's important that the nullability of the properties matches the value of
the required attribute of the
org.apache.maven.plugins.annotations.Parameter annotation, or you may get
unfriendly errors at runtime.
package com.example
import org.apache.maven.plugin.AbstractMojo
import org.apache.maven.plugins.annotations.Mojo
import org.apache.maven.plugins.annotations.Parameter
/**
* Example description.
*/
@Mojo(name = "example")
class ExampleMojo : AbstractMojo() {
/**
* Optional parameter description.
*/
@Deprecated("Example optional parameter deprecated message.")
@Parameter(name = "optionalParameter")
var optionalParameter: String? = null
/**
* Required parameter description.
*
* @since 1.1
*/
@Parameter(name = "requiredParameter", required = true)
lateinit var requiredParameter: String
override fun execute() {
// Perform plugin action here
}
}Your POM will include the following:
<?xml version="1.0" encoding="UTF-8"?>
<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.example</groupId>
<artifactId>example-maven-plugin</artifactId>
<version>1.0.0-SNAPSHOT</version>
<packaging>maven-plugin</packaging>
<prerequisites>
<maven>${maven.version}</maven>
</prerequisites>
<properties>
<kotlin.version>1.7.10</kotlin.version>
<maven.compiler.source>1.8</maven.compiler.source>
<maven.compiler.target>1.8</maven.compiler.target>
<maven.version>3.6.3</maven.version>
<project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
<project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding>
</properties>
<dependencies>
<dependency>
<groupId>org.apache.maven</groupId>
<artifactId>maven-core</artifactId>
<version>${maven.version}</version>
</dependency>
<dependency>
<groupId>org.apache.maven</groupId>
<artifactId>maven-plugin-api</artifactId>
<version>${maven.version}</version>
</dependency>
<dependency>
<groupId>org.jetbrains.kotlin</groupId>
<artifactId>kotlin-stdlib-jdk8</artifactId>
<version>${kotlin.version}</version>
</dependency>
<dependency>
<groupId>org.apache.maven.plugin-tools</groupId>
<artifactId>maven-plugin-annotations</artifactId>
<version>3.6.4</version>
<scope>provided</scope>
</dependency>
<dependency>
<groupId>org.jetbrains.kotlin</groupId>
<artifactId>kotlin-test-junit</artifactId>
<version>${kotlin.version}</version>
<scope>test</scope>
</dependency>
</dependencies>
<build>
<sourceDirectory>src/main/kotlin</sourceDirectory>
<testSourceDirectory>src/test/kotlin</testSourceDirectory>
<plugins>
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-plugin-plugin</artifactId>
<version>3.6.4</version>
<configuration>
<extractors>
<!--
Use only the Kotlin extractor (also supports annotated Java
sources)
-->
<extractor>kotlin</extractor>
</extractors>
</configuration>
<dependencies>
<dependency>
<!-- Add kotlin-maven-plugin-tools as a dependency to the maven-plugin-plugin -->
<groupId>com.github.gantsign.maven.plugin-tools</groupId>
<artifactId>kotlin-maven-plugin-tools</artifactId>
<!-- Replace @version@ with the latest kotlin-maven-plugin-tools release -->
<version>@version@</version>
</dependency>
</dependencies>
<executions>
<execution>
<id>default-descriptor</id>
<phase>process-classes</phase>
</execution>
<execution>
<id>help-goal</id>
<goals>
<goal>helpmojo</goal>
</goals>
</execution>
</executions>
</plugin>
<plugin>
<groupId>org.jetbrains.kotlin</groupId>
<artifactId>kotlin-maven-plugin</artifactId>
<version>${kotlin.version}</version>
<configuration>
<jvmTarget>1.8</jvmTarget>
</configuration>
<executions>
<execution>
<id>compile</id>
<goals>
<goal>compile</goal>
</goals>
<phase>process-sources</phase>
</execution>
<execution>
<id>test-compile</id>
<goals>
<goal>test-compile</goal>
</goals>
<phase>test-compile</phase>
</execution>
</executions>
</plugin>
</plugins>
</build>
</project>This software is licensed under the terms in the file named "LICENSE" in the root directory of this project. This project has dependencies that are under different licenses.
John Freeman
GantSign Ltd. Company No. 06109112 (registered in England)