Groovy & Gradle: JVM Automation and Build Engineering · レッスン

タスクのプロパティと設定

カスタムタスクへのプロパティの追加と設定方法を学び、インクリメンタルビルドを実現します。

「タスクのプロパティと設定」はCoddyKit上の無料Groovy & Gradle: JVM Automation and Build Engineeringレッスンです。これはレッスン3/4です。下記で完全なレッスンを無料で読むことができます。その後、ブラウザ内の組み込みコードエディタと24時間対応のAIチューターでハンズオン演習できます。これはGroovy & Gradle: JVM Automation and Build Engineering学習パスの一部であり、ウェブとCoddyKitアプリ全体で進捗が同期されます。 Groovy & Gradle: JVM Automation and Build Engineeringコースには全4レッスンが含まれています。

このレッスンの一部はまだ翻訳されておらず、英語で表示されています。

What are Task Properties?

Custom Gradle tasks can be made highly flexible by adding properties. These properties act like variables that allow you to configure a task's behavior from your build.gradle script.

Using properties makes your custom tasks reusable and adaptable to different project needs without having to change their core logic.

Defining Simple Properties

To add a property to a custom task, you simply declare a public field within your task class. For basic types like String, int, or boolean, this is straightforward.

For more advanced scenarios, Gradle also offers dedicated Property types, but we'll start with simple declarations.

Custom Task with a Property

Here's a basic custom task defined directly in build.gradle. It has a message property that will be printed when the task runs. Notice the default value set for the property.

import org.gradle.api.DefaultTask
import org.gradle.api.tasks.TaskAction

class MyMessageTask extends DefaultTask {
    String message = "Default task message"

    @TaskAction
    void printMessage() {
        println "Task says: ${message}"
    }
}

task helloWorld(type: MyMessageTask)

Configuring Task Properties

Once a task property is defined, you can easily set its value from your build.gradle file. This is done within the task's configuration block, which allows you to customize the task instance.

Run the example to see how the default message is overridden.

import org.gradle.api.DefaultTask
import org.gradle.api.tasks.TaskAction

class MyMessageTask extends DefaultTask {
    String message = "Default task message"

    @TaskAction
    void printMessage() {
        println "Task says: ${message}"
    }
}

task helloWorld(type: MyMessageTask) {
    message = "Hello from CoddyKit!"
}

Inputs for Incremental Builds

One of Gradle's most powerful features is incremental builds. This means Gradle can skip tasks if their inputs and outputs haven't changed since the last build, saving a lot of time.

To enable this, you must tell Gradle which properties are considered task inputs. These are properties whose values influence the task's outcome.

Declaring Input Properties

You mark a property as an input using the @Input annotation. Gradle will then track its value. If the value changes between builds, the task will execute. If not, Gradle can mark it as UP-TO-DATE and skip it.

For file or directory inputs, use @InputFile, @InputDirectory, or @InputFiles.

import org.gradle.api.DefaultTask
import org.gradle.api.tasks.Input
import org.gradle.api.tasks.TaskAction

class MyInputTask extends DefaultTask {
    @Input
    String greeting = "Hola!"

    @TaskAction
    void greet() {
        println "Greeting: ${greeting}"
    }
}

task sayHello(type: MyInputTask) {
    greeting = "Bonjour!"
}

Outputs for Incremental Builds

Equally important are outputs. These are the files or directories that your task creates or modifies during its execution. Gradle also tracks these to determine if a task is up-to-date.

If a task's inputs haven't changed AND its declared outputs are present and valid, Gradle knows the task doesn't need to run again.

Declaring Output Properties

You use annotations like @OutputFile for a single result file or @OutputDirectory for a directory containing results. These tell Gradle where the task's generated artifacts will be stored.

The task will ensure the parent directory exists before writing the file.

import org.gradle.api.DefaultTask
import org.gradle.api.tasks.Input
import org.gradle.api.tasks.OutputFile
import org.gradle.api.tasks.TaskAction

class MyOutputFileTask extends DefaultTask {
    @Input
    String content = "Default report content."

    @OutputFile
    File outputFile = project.file("build/reports/output.txt")

    @TaskAction
    void generateFile() {
        outputFile.parentFile.mkdirs()
        outputFile.write(content)
        println "Generated: ${outputFile.name}"
    }
}

task generateReport(type: MyOutputFileTask) {
    content = "Report data for: " + new Date().format("yyyy-MM-dd HH:mm:ss")
}

The Power of Incremental Builds

By correctly declaring both inputs and outputs, you unlock Gradle's powerful incremental build feature. This means your tasks only run when necessary, drastically speeding up build times.

This optimization is crucial for efficient development workflows and robust CI/CD pipelines, ensuring quick feedback and resource savings.

Quick Check on Properties

Imagine you have a custom Gradle task that takes a specific configuration file as an input. Which annotation would you use for the property that defines the path to this single configuration file?

Recap: Task Properties & Incremental Builds

In this lesson, you learned how to add properties to custom tasks, making them configurable and reusable. You also discovered how to mark properties as inputs (e.g., @Input, @InputFile) and outputs (e.g., @OutputFile, @OutputDirectory).

These annotations are key to enabling Gradle's powerful incremental build feature, which significantly speeds up your builds by skipping tasks that are already up-to-date. Keep practicing to master efficient task configuration!

よくある質問

「タスクのプロパティと設定」レッスンは無料ですか？

はい。「タスクのプロパティと設定」の完全なテキストはこのウェブで無料で読めます。インタラクティブに演習し（組み込みコードエディタと24時間対応のAIチューター）、Groovy & Gradle: JVM Automation and Build Engineeringコースの残りをアンロックするには、CoddyKit PROにアップグレードしてください。 Groovy & Gradle: JVM Automation and Build Engineeringコースには全4レッスンが含まれています。

「タスクのプロパティと設定」で何を学びますか？

カスタムタスクへのプロパティの追加と設定方法を学び、インクリメンタルビルドを実現します。ブラウザで直接実行するハンズオンコードでGroovy & Gradle: JVM Automation and Build Engineeringを演習し、24時間対応のAIチューターがレッスンを進める中での質問に答えます。

Groovy & Gradle: JVM Automation and Build Engineeringを始めるのに経験は必要ですか？

事前経験は必要ありません。CoddyKitのGroovy & Gradle: JVM Automation and Build Engineeringは初級者から上級者向けに構成されているため、ここから始めるか最初から始めて、自分のペースで進むことができます。これはレッスン3/4です。

「タスクのプロパティと設定」レッスンにはどのくらい時間がかかりますか？

ほとんどのCoddyKitレッスンは約5～10分かかります。各レッスンはコンパクトでインタラクティブなので、着実に進歩し、ウェブとアプリ全体で正確に前回の場所から再開できます。

このGroovy & Gradle: JVM Automation and Build Engineeringレッスンでコードを書いて実行できますか？

はい。すべてのGroovy & Gradle: JVM Automation and Build Engineeringレッスンに組み込みコードエディタが含まれているため、ブラウザでリアルコードを書いて実行し、即座のAIフィードバックを取得できます。ローカル設定は不要です。

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