来自build.sbt的参考Scala文件

如果我理解正确，你的项目看起来像

root
  project
    build.properties
    build.sbt
  subproject1
    src
      main
        scala
          com.example.package1
            App.scala
  subproject2
    src
      main
        scala
          com.example.package2
  build.sbt

在project/build.sbt我可以写

Compile / unmanagedSourceDirectories += baseDirectory.value / ".." / "subproject1" / "src" / "main" / "scala"

假设subproject1/src/main/scala/com/example/package1/App.scala是

package com.example.package1

object App {
  def foo(): Unit = println("foo")
}

然后build.sbt我可以在根目录下调用foo

name := "sbtdemo"

version := "0.1"

ThisBuild / scalaVersion := "2.13.4"

lazy val sampleUnitTask = taskKey[Unit]("A sample unit task.")

lazy val rootSettings: Seq[Setting[_]] = Seq(
  sampleUnitTask := {
    com.example.package1.App.foo()
  }
)

lazy val root = project
  .in(file("."))
  .dependsOn(subproject1, subproject2)
  .settings(rootSettings)

lazy val subproject1 = project
  .in(file("subproject1"))

lazy val subproject2 = project
  .in(file("subproject2"))

如果在sbt shell中运行，root/sampleUnitTask它将打印foo。

我使用创建了Play项目sbt new playframework/play-scala-seed.g8。一切似乎都正常。我添加project/build.sbt和subproject1/src/main/scala/com/example/package1/App.scala如上所述。然后用下面的根build.sbt

name := """playframeworkdemo"""
organization := "com.example"

version := "1.0-SNAPSHOT"

lazy val sampleUnitTask = taskKey[Unit]("A sample unit task.")

lazy val rootSettings: Seq[Setting[_]] = Seq(
  sampleUnitTask := {
    com.example.package1.App.foo()
  }
)

lazy val root = (project in file(".")).enablePlugins(PlayScala)
  .dependsOn(subproject1, subproject2)
  .settings(rootSettings)

ThisBuild / scalaVersion := "2.13.3"

libraryDependencies += guice
libraryDependencies += "org.scalatestplus.play" %% "scalatestplus-play" % "5.0.0" % Test

// Adds additional packages into Twirl
//TwirlKeys.templateImports += "com.example.controllers._"

// Adds additional packages into conf/routes
// play.sbt.routes.RoutesKeys.routesImport += "com.example.binders._"

lazy val subproject1 = project
  .in(file("subproject1"))

lazy val subproject2 = project
  .in(file("subproject2"))

root/sampleUnitTask在sbt shell打印文件中执行foo。