scala – sbt项目构建中的多个目标目录

.
├── build.sbt
├── project
│?? ├── build.properties
│?? └── plugins.sbt
└── src
    ├── main
    │?? └── java
    │??     └── smcho
    │??         └── App.java
    └── test
        └── java
            └── smcho
                └── AppTest.java

使用sbt包,我有三个目标目录,target2和target3具有相似的结构.

.
├── build.sbt
├── project
│?? ├── build.properties
│?? ├── plugins.sbt
│?? ├── project
│?? │?? └── target <---------- TARGET 1
│?? └── target     <---------- TARGET 2
│??     ├── config-classes
│??     ├── resolution-cache
│??     ├── scala-2.10
│??     └── streams
├── src
│?? ├── main
│?? │?? └── java
│?? └── test
│??     └── java
└── target  <--------------- TARGET 3
    ├── resolution-cache
    │?? ├── com.example
    │?? └── reports
    ├── scala-2.11
    │?? ├── classes
    │?? └── hello_2.11-0.1.0.jar
    └── streams
        ├── $global
        └── compile

为什么这样？有趣的是,sbt clean不会删除目标目录,有没有办法让一个简单的目标,以便我可以轻松删除它们？

这是build.sbt：

lazy val hello = taskKey[Unit]("An example task")
val junit = "junit" % "junit" % "4.11" % "test"

lazy val commonSettings = Seq( 
    organization := "com.example",version := "0.1.0",scalaVersion := "2.11.4"
)

lazy val root = (project in file(".")). 
    settings(
        commonSettings: _*
). 
    settings(
        hello := { println("Hello!") },name := "hello",libraryDependencies += junit
)