generate a version class

Author: hauner

build.gradle

@@ -55,6 +55,17 @@ repositories {
     }
 }
 
+sourceSets {
+  main {
+    java {
+        srcDirs += "${buildDir}/version/java/main"
+    }
+  }
+}
+
+compileJava.dependsOn "generateVersion"
+
+
 test {
     useJUnitPlatform()
 }
@@ -156,4 +167,5 @@ dokka {
     outputDirectory = "$buildDir/docs/kotlin"
 }
 
+apply plugin: VersionPlugin
 apply from: "${rootProject.rootDir}/gradle/publishing.gradle"

buildSrc/src/main/groovy/VersionPlugin.groovy

@@ -0,0 +1,44 @@
+import org.gradle.api.Action
+import org.gradle.api.Plugin
+import org.gradle.api.Project
+
+/**
+ * provides a "generateVersion" task to a create a simple Version.java class:
+ *
+ * <pre>{@code
+ * package io.openapiprocessor.spring;
+ *
+ * public class Version {
+ *     public static final String version = "${project.version}";
+ * }
+ * }</pre>
+ *
+ *
+ * The io/openapiprocessor/spring/Version.java file is generated to:
+ *
+ * $(project.buildDir}/main/java
+ *
+ * Add it as a source directory to include it in compilation.
+ */
+class VersionPlugin implements Plugin<Project> {
+
+    void apply(Project project) {
+        project.afterEvaluate (new Action<Project> () {
+
+            @Override
+            void execute (Project prj) {
+                prj.tasks.register ('generateVersion', VersionTask , new Action<VersionTask>() {
+
+                    @Override
+                    void execute (VersionTask task) {
+                        task.targetDir = prj.buildDir
+                        task.version = prj.version
+                    }
+
+                })
+            }
+
+        })
+    }
+
+}

buildSrc/src/main/groovy/VersionTask.groovy

@@ -0,0 +1,54 @@
+import org.gradle.api.DefaultTask
+import org.gradle.api.tasks.Internal
+import org.gradle.api.tasks.OutputDirectory
+import org.gradle.api.tasks.TaskAction
+
+import java.nio.file.Files
+import java.nio.file.Path
+import java.time.Instant
+
+/**
+ * simple task to create a Version class.
+ */
+class VersionTask extends DefaultTask {
+
+    /**
+     * Target directory for the generated version class.
+     *
+     * Used by gradle for the up-to-date check.
+     */
+    @OutputDirectory
+    String targetDir
+
+    @Internal
+    String version
+
+    /**
+     * generate the version class.
+     */
+    @TaskAction
+    void generateVersion () {
+        def path = Path.of (
+            targetDir, "version", "main", "java", "io", "openapiprocessor", "spring")
+
+        Files.createDirectories(path)
+
+        def target = path.resolve ("Version.java")
+
+        target.text = """\
+/*
+ * DO NOT MODIFY - this file was auto generated by buildSrc/src/main/groovy/VersionPlugin.groovy
+ *
+ * ${Instant.now ().toString ()}
+ */
+
+package io.openapiprocessor.spring;
+ 
+public class Version {
+    public static final String version = "${version}"; 
+}
+ 
+"""
+    }
+
+}