Question

我正在尝试使用gradle编写kotlin插件。它应该像这样工作。在提供配置时

apply plugin: 'appenv'

app {
    srcLink ""
    downloadPath ""
}

应该允许从srcLink下载文件并使用任务downloadPath存储在downloadAll

我创建了扩展类

open class ApplicationEnvironmentExtension {
    val project: Any?

    constructor(project: Any?) {
        this.project = project
    }

    var srcLink: String = ""
    var downloadPath: String = ""
}

创建插件类

class ApplicationEnvironmentPlugin : Plugin<Project> {

    override fun apply(project: Project) {
        project.extensions.create("app", ApplicationEnvironmentExtension::class.java)
        project.task(mapOf ("type" to Download::class.java), "downloadAll")
    }
}

这是他的任务

class Download : DefaultTask() {

    @TaskAction
    fun download() {
        val extension = this.project.extensions.getByName("app") as ApplicationEnvironmentExtension
        DownloadUtils.download(extension.srcLink, extension.downloadPath)
    }
}

我构建它并将其作为jar依赖项添加到我的项目中。要检查是否添加了任务，请运行gradle tasks。但在此期间我收到了错误

Could not create an instance of type com.lapots.gradle.plugins.appenv.ApplicationEnvironmentExtension_Decorated.

在stacktrace中我得到了

Caused by: org.gradle.internal.reflect.ObjectInstantiationException: Could not create an instance of type com.lapots.gradle.plugins.appenv.ApplicationEnvironmentExtension_Decorated.
        at org.gradle.internal.reflect.DirectInstantiator.newInstance(DirectInstantiator.java:53)
        at org.gradle.api.internal.ClassGeneratorBackedInstantiator.newInstance(ClassGeneratorBackedInstantiator.java:36)
        at org.gradle.api.internal.plugins.DefaultConvention.create(DefaultConvention.java:106)
        at com.lapots.gradle.plugins.appenv.ApplicationEnvironmentPlugin.apply(ApplicationEnvironmentPlugin.kt:11)
        at com.lapots.gradle.plugins.appenv.ApplicationEnvironmentPlugin.apply(ApplicationEnvironmentPlugin.kt:8)
        at org.gradle.api.internal.plugins.ImperativeOnlyPluginApplicator.applyImperative(ImperativeOnlyPluginApplicator.java:35)
        at org.gradle.api.internal.plugins.RuleBasedPluginApplicator.applyImperative(RuleBasedPluginApplicator.java:43)
        at org.gradle.api.internal.plugins.DefaultPluginManager.doApply(DefaultPluginManager.java:144)
        ... 58 more         
Caused by: java.lang.IllegalArgumentException: Could not find any public constructor for class com.lapots.gradle.plugins.appenv.ApplicationEnvironmentExtension_Decorated which accepts parameters [].
        at org.gradle.internal.reflect.DirectInstantiator.newInstance(DirectInstantiator.java:44)
        ... 65 more

有什么问题？我应该为扩展提供一些附加构造函数吗？

Answer 1

扩展需要一个默认（no-arg）构造函数。如果您确实需要为扩展程序中的值指定字段，则可以使用C = A[~A["fake_index_col"].isin(B["fake_index_col"])] del C["fake_index_col"] print C Name Surname Age 1 Glenn Quagmire 35 2 Joe Swanson 38 3 Cleveland Brown 45并在插件中创建扩展程序后对其进行分配。

在这种情况下，看起来你不需要你的lateinit var字段，所以你可以摆脱它和构造函数。否则，如果您确实需要该字段，仍然会删除构造函数，但是您需要使project变量的默认值为project。

Answer 2

我不确定ApplicationEnvironmentExtension在构建过程中会发生什么，因此我将假定它是Gradle Project的一个实例。试试这个

project.extensions.create("app", ApplicationEnvironmentExtension::class.java, project)

插件在调用Project.create()时需要传递构造函数参数。如果它是Gradle Project的实例，则ApplicationEnvironmentExtension.project的类型应为Project，而不是模糊的类型Any。

无法创建gradle插件扩展的实例

2 个答案: