JuneLeo's Blog
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构建编译JavaGradlePlugin

发表于 更新于

https://docs.gradle.org/current/userguide/java_gradle_plugin.html#sec:gradle_plugin_dev_usage

  • gradleApi()依赖项添加到配置中，并在任务执行api期间执行插件元数据的验证
  • 集成TestKit
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apply plugin: 'java-gradle-plugin'
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gradlePlugin {
    plugins {
        simplePlugin {
            id = 'org.gradle.sample.simple-plugin'
            implementationClass = 'org.gradle.sample.SimplePlugin'
        }
    }
}

jar在文件META-INF目录中生成插件描述符。

image.png

gradle-api 中 JavaGradlePluginPlugin

核心代码

这里只关注properties的生成

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private void configureDescriptorGeneration(Project project, GradlePluginDevelopmentExtension extension) {
    // 创建一个task
    TaskProvider<GeneratePluginDescriptors> generatePluginDescriptors = project.getTasks().register("pluginDescriptors", GeneratePluginDescriptors.class, (task) -> {
        task.setGroup("Plugin development");
        task.setDescription("Generates plugin descriptors from plugin declarations.");
        // 设置plugins数据
        task.getDeclarations().set(extension.getPlugins());
        // 设置输出目录
        task.getOutputDirectory().set(project.getLayout().getBuildDirectory().dir(task.getName()));
    });
    // 复制 生成的properties
    project.getTasks().named("processResources", Copy.class, (task) -> {
        CopySpec copyPluginDescriptors = task.getRootSpec().addChild();
        copyPluginDescriptors.into("META-INF/gradle-plugins");
        copyPluginDescriptors.from(new Object[]{generatePluginDescriptors});
    });
}
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public class GeneratePluginDescriptors extends DefaultTask {
    private final ListProperty<PluginDeclaration> declarations;
    private final DirectoryProperty outputDirectory;

    public GeneratePluginDescriptors() {
        ObjectFactory objectFactory = this.getProject().getObjects();
        this.declarations = objectFactory.listProperty(PluginDeclaration.class);
        this.outputDirectory = objectFactory.directoryProperty();
    }

    @Input
    public ListProperty<PluginDeclaration> getDeclarations() {
        return this.declarations;
    }

    @OutputDirectory
    public DirectoryProperty getOutputDirectory() {
        return this.outputDirectory;
    }

    @TaskAction   // task执行入口
    public void generatePluginDescriptors() {
        // 输出目录
        File outputDir = ((Directory)this.outputDirectory.get()).getAsFile();
        this.clearOutputDirectory(outputDir);
        // plugins
        Iterator var2 = ((List)this.getDeclarations().get()).iterator();

        while(var2.hasNext()) {
            PluginDeclaration declaration = (PluginDeclaration)var2.next();
            //注意这里的命名(plugin-id).properties
            File descriptorFile = new File(outputDir, declaration.getId() + ".properties");
            Properties properties = new Properties();
            // implementation-class=class路径
            properties.setProperty("implementation-class", declaration.getImplementationClass());
            // 写入文件中
            this.writePropertiesTo(properties, descriptorFile);
        }

    }

    @Inject
    protected Deleter getDeleter() {
        throw new UnsupportedOperationException("Decorator takes care of injection");
    }

    private void clearOutputDirectory(File directoryToClear) {
        try {
            this.getDeleter().ensureEmptyDirectory(directoryToClear);
        } catch (IOException var3) {
            throw new UncheckedIOException(var3);
        }
    }

    private void writePropertiesTo(Properties properties, File descriptorFile) {
        try {
            PropertiesUtils.store(properties, descriptorFile);
        } catch (IOException var4) {
            throw new UncheckedIOException(var4);
        }
    }
}