无法获得未知 属性 'android'

Could not get unknown property 'android'

我一直在阅读本教程以了解如何为 Unity 创建 Android 服务: http://eppz.eu/blog/unity-android-plugin-tutorial-2/

那里显示了一个 Gradle 构建脚本片段,所以我复制了它并稍作修改,以便它可以正确部署到我的 Unity 项目中。

但是当我 运行 / 同步 Gradle 脚本时,它似乎抱怨其中的 'android' 变量/关键字(或其他任何内容)。我不认为这是由我的修改引起的,因为 android.libraryVariants.all { ... } 部分在教程开头:

(编辑:我将整个 build.gradle 文件放在这里,以防我遗漏任何明显的东西)

// Top-level build file where you can add configuration options common to all sub-projects/modules.

buildscript {
    repositories {
        jcenter()
    }
    dependencies {
        classpath 'com.android.tools.build:gradle:2.2.2'

        // NOTE: Do not place your application dependencies here; they belong
        // in the individual module build.gradle files
    }
}

allprojects {
    repositories {
        jcenter()
    }
}

task clean(type: Delete) {
    delete rootProject.buildDir
}

android.libraryVariants.all { variant ->
    // Task names.
    String pluginName = "DemoPlugin";
    String variantName = "${variant.name.capitalize()}"; // Like 'Debug'
    String deployTaskGroup = "plugin";
    String deployTaskName = "deploy${variantName}PluginArchive"; // Like 'deployDebugPluginArchive'
    String dependencyTaskName = "assemble${variantName}"; // Like 'assembleDebug'
    // Source.
    String sourceAARFolder = "${buildDir.getPath()}/release-jars/";
    String sourceAARName = "${project.name}-${variant.name}.jar";

    // Pierre: Unity project directory
    String targetProjDir = System.env.UNITY_PROJECT;

    // Target.
    String targetAssetFolder = "Assets/Plugins/${pluginName}";
    String targetAARFolder = "${targetProjDir}/${targetAssetFolder}"; // Navigate into 'Assets'
    String targetAARName = "${pluginName}.jar"; // The form you ship your plugin
    // Create task.
    task(deployTaskName, dependsOn: dependencyTaskName, type: Copy) {
        from(sourceAARFolder)
        into(targetAARFolder)
        include(sourceAARName)
        rename(sourceAARName, targetAARName)
    }.group = deployTaskGroup;
}

知道是什么导致了这个错误吗?

Error:(25, 1) A problem occurred evaluating root project 'DemoService'. Could not get unknown property 'android' for root project 'DemoService' of type org.gradle.api.Project.

将代码粘贴到模块的构建文件中,而不是顶层文件中。