我正在尝试创建一个可重用的 gradle 任务，该任务从顶层访问某些内容。这有效：

val foo = 42

tasks.register("foosimple") {
    println(foo)
}

但是使用来自开发自定义 Gradle 任务类型的修改示例不会：

open class Foo : DefaultTask() {
    @TaskAction
    fun foo() {
        println(foo)
    }
}
tasks.register<Foo>("foo")

失败了：

FAILURE: Build failed with an exception.

* What went wrong:
A problem occurred configuring root project 'keycloak-spi'.
> Could not create task ':foo'.
   > Could not create task of type 'Foo'.
      > The constructor for type Build_gradle.Foo should be annotated with @Inject.

* Try:
Run with --stacktrace option to get the stack trace. Run with --info or --debug option to get more log output. Run with --scan to get full insights.

有人可以阐明我在这里做错了什么吗？如果我foo()用println(42)它替换的内容，当然。但我实际上想从顶层访问一些东西......

更多细节

--stacktrace 对我没有帮助：

* Exception is:
org.gradle.api.ProjectConfigurationException: A problem occurred configuring root project 'keycloak-spi'.
        at org.gradle.execution.TaskNameResolver.getExistingTask(TaskNameResolver.java:116)
        at org.gradle.execution.TaskNameResolver.access$000(TaskNameResolver.java:32)
        at org.gradle.execution.TaskNameResolver$MultiProjectTaskSelectionResult.collect(TaskNameResolver.java:177)
        at org.gradle.execution.TaskNameResolver$MultiProjectTaskSelectionResult.collectTasks(TaskNameResolver.java:169)
        at org.gradle.execution.TaskNameResolver.selectWithName(TaskNameResolver.java:55)
        at org.gradle.execution.TaskSelector.getSelection(TaskSelector.java:104)
        at org.gradle.execution.TaskSelector.getSelection(TaskSelector.java:82)
        at org.gradle.execution.commandline.CommandLineTaskParser.parseTasks(CommandLineTaskParser.java:42)

因此，我尝试@Inject在构造函数上添加一个注释，但显然，就像我一样，gradle 不知道@Inject：

open class Foo @Inject constructor()  : DefaultTask() {
    @TaskAction
    fun foo() {
        println(foo)
    }
}

失败了：

Line 70: class Foo @Inject constructor() {}
                  ^ Unresolved reference: Inject

这是 Intellij 的唯一建议：

open class Foo @javax.inject.Inject constructor()  : DefaultTask() {
    @TaskAction
    fun foo() {
        println(foo)
    }
}

现在它失败了：

FAILURE: Build failed with an exception.

* What went wrong:
A problem occurred configuring root project 'keycloak-spi'.
> Could not create task ':foo'.
   > Could not create task of type 'Foo'.
      > 0

所以现在它接受了@Inject注释，但仍然不起作用。我现在放弃并问你们......

回答

val foo = 42

open class Foo : DefaultTask() {
    @Input
    var fooToPrint: Int = 0

    @TaskAction
    fun foo() {
        println(fooToPrint)
    }
}
tasks.register<Foo>("foo") {
    fooToPrint = foo
}