在 sbt 中驱逐特定的传递依赖

Question

假设一个小型测试项目（sbt 0.13.8，完整项目为gist）：

name := "test"

organization := "org.example"

version := "0.1.0-SNAPSHOT"

scalaVersion := "2.11.6"

libraryDependencies ++= Seq (
  "com.lowagie"              %  "itext"         % "4.2.1",
  "com.github.wookietreiber" %% "scala-chart"   % "0.4.2"
)

依赖树如下：

dependencyTree
[info] org.example:test_2.11:0.1.0-SNAPSHOT [S]
[info]   +-com.github.wookietreiber:scala-chart_2.11:0.4.2 [S]
[info]   | +-org.jfree:jfreechart:1.0.17
[info]   | | +-org.jfree:jcommon:1.0.21
[info]   | | +-xml-apis:xml-apis:1.3.04
[info]   | | 
[info]   | +-org.scala-lang.modules:scala-swing_2.11:1.0.1 [S]
[info]   | 
[info]   +-com.lowagie:itext:4.2.1
[info]     +-bouncycastle:bctsp-jdk14:138
[info]     | +-org.bouncycastle:bctsp-jdk14:1.38
[info]     |   +-org.bouncycastle:bcmail-jdk14:1.38
[info]     |   | +-org.bouncycastle:bcprov-jdk14:1.38
[info]     |   | 
[info]     |   +-org.bouncycastle:bcprov-jdk14:1.38
[info]     |   
[info]     +-dom4j:dom4j:1.6.1
[info]     | +-xml-apis:xml-apis:1.0.b2 (evicted by: 1.3.04)
[info]     | +-xml-apis:xml-apis:1.3.04
[info]     | 
[info]     +-jfree:jfreechart:1.0.12
[info]     | +-jfree:jcommon:1.0.15
[info]     | 
[info]     +-org.swinglabs:pdf-renderer:1.0.5
[info]     
[success] Total time: 0 s, completed Jun 2, 2015 12:16:14 PM

问题是依赖jfreechart 被scala-chart 和itext 引入（jcommon 也是如此，但我将专注于jfreechart）。但是，itext 引入的稍旧版本使用另一个组织名称（jfree 与 org.jfree）。

通常，如果它们使用相同的组织，那么旧的组织会被驱逐（就像 xml-apis 的示例中所做的那样），只要存在二进制兼容性，就不会有冲突。

现在真正的冲突是依赖jfree:jfreechart 和org.jfree:jfreechart 都在类路径上并提供相同的类。编译工作正常，sbt 甚至没有抱怨。举个例子下面的例子App：

package org.example

import scalax.chart.api._

object Main extends App {
  val data = for {
    i <- 1 to 5
    category = i.toString
    date = new org.jfree.data.time.Day(i, 2, 1998)
    value = i * 2
  } yield category -> Map(date -> value)

  val chart = XYAreaChart.stacked(data.toTimeTable)

  chart.saveAsPDF("/tmp/my-chart.pdf")
}

这编译得很好！我不知道 sbt 如何选择使用哪个依赖项。如果您尝试实际运行它，一切都会爆炸：

sbt @ test $ compile
[info] Updating {file:/home/wookietreiber/projects/scala/jfree-itext-test/}jfree-itext-test...
[info] Resolving jline#jline;2.12.1 ...
[info] Done updating.
[info] Compiling 1 Scala source to /tmp/sbt/test/scala-2.11/classes...
[success] Total time: 1 s, completed Jun 2, 2015 1:18:36 PM
sbt @ test $ run
[info] Running org.example.Main 
[error] (run-main-1) java.lang.NoSuchMethodError: org.jfree.data.time.TimeTableXYDataset.add(Lorg/jfree/data/time/TimePeriod;Ljava/lang/Number;Ljava/lang/Comparable;Z)V
java.lang.NoSuchMethodError: org.jfree.data.time.TimeTableXYDataset.add(Lorg/jfree/data/time/TimePeriod;Ljava/lang/Number;Ljava/lang/Comparable;Z)V
        at scalax.chart.module.RichChartingCollections$RichCategorizedTuple2s$$anonfun$toTimeTable$1$$anonfun$apply$4.apply(RichChartingCollections.scala:300)
...

为了解决这个问题，我需要专门从依赖列表/类路径中逐出/删除旧的jfree:jfreechart 和jfree:jcommon 版本。这可能吗？如果可以，怎么办？

---

我发现的另一个问题是 sbt-assembly 出现如下错误（对于每个重复文件）：

[error] deduplicate: different file contents found in the following:
[error] /home/wookietreiber/.ivy2/cache/jfree/jfreechart/jars/jfreechart-1.0.12.jar:org/jfree/data/KeyedValues2D.class
[error] /home/wookietreiber/.ivy2/cache/org.jfree/jfreechart/jars/jfreechart-1.0.17.jar:org/jfree/data/KeyedValues2D.class

Answer 1

您需要在 *.sbt 或 *.scala 项目定义中定义 mergeStragey in assembly 才能使用 sbt-assembly 命令。下面是一个示例。

mergeStrategy in assembly <<= (mergeStrategy in assembly) { (old) =>
  {
    case PathList("javax", "servlet", xs @ _*) => MergeStrategy.last
    case PathList("javax", "activation", xs @ _*) => MergeStrategy.last
    case PathList("org", "apache", xs @ _*) => MergeStrategy.last
    case PathList("com", "google", xs @ _*) => MergeStrategy.last
    case PathList("com", "esotericsoftware", xs @ _*) => MergeStrategy.last
    case PathList("com", "codahale", xs @ _*) => MergeStrategy.last
    case PathList("com", "yammer", xs @ _*) => MergeStrategy.last
    case "about.html" => MergeStrategy.rename
    case "META-INF/ECLIPSEF.RSA" => MergeStrategy.last
    case "META-INF/mailcap" => MergeStrategy.last
    case "META-INF/mimetypes.default" => MergeStrategy.last
    case "plugin.properties" => MergeStrategy.last
    case "log4j.properties" => MergeStrategy.last
    case x => old(x)
  }
}

如果您清楚导致问题的传递 jar 是什么，您可以将其排除在您的 libraryDependencies 中。例如，我从对 play 2.3.6 的直接依赖中排除了 httpclient jar，它依赖于更高版本的 httpclient，这不是我想要的。

 "com.typesafe.play" %% "play" % "2.3.6" exclude("org.apache.httpcomponents", "httpclient") 

在您的情况下，您可以对引入这个旧 jar 的直接依赖项执行 exclude("jfree", "jfreechart")。