sbt - 重複したクラスをsbtアセンブリから除外するにはどうすればよいですか?

Question

2 つの依存関係がまったく同じクラスを持つ状況があります (依存関係の 1 つがそれをコピーし、独自のソースに含めたため)。

これによりsbt assembly、重複排除チェックが失敗します。

特定の jar からクラスを除外するにはどうすればよいですか?

Answer 1

You need a mergeStrategy, which will take one of the files.

mergeStrategy in assembly := {
    case PathList("path", "to", "your", "DuplicatedClass.class") => MergeStrategy.first
    case x => (mergeStrategy in assembly).value(x)
}

Update

If you want to handle the file depending on the JAR which it came from, I don't think you can with the merge strategies that assembly plugin defines. What you could do you could define your own strategy.

I would invert your condition though. I think the question should be "How can I include a class from a particular JAR?". The reason is that there can be more than two JARs having the same class, and you can only include one in the end.

You can tell from where the file comes by using AssemblyUtils.sourceOfFileForMerge.

project/IncludeFromJar.scala

import sbtassembly._
import java.io.File
import sbtassembly.Plugin.MergeStrategy

class IncludeFromJar(val jarName: String) extends MergeStrategy {

  val name = "includeFromJar"

  def apply(args: (File, String, Seq[File])): Either[String, Seq[(File, String)]] = {
    val (tmp, path, files) = args
    val includedFiles = files.flatMap { f =>
      val (source, _, _, isFromJar) = sbtassembly.AssemblyUtils.sourceOfFileForMerge(tmp, f)
      if(isFromJar && source.getName == jarName) Some(f -> path) else None
    }
    Right(includedFiles)
  }

}

build.sbt

mergeStrategy in assembly := {
    case PathList("path", "to", "your", "DuplicatedClass.class") => new IncludeFromJar("jarname.jar")
    case x => (mergeStrategy in assembly).value(x)
}