ProGuard 使用 sbt-proguard 说 Unsupported class version number [52.0] (maximum 51.0, Java 1.7) [英] ProGuard says Unsupported class version number [52.0] (maximum 51.0, Java 1.7) with sbt-proguard

问题描述

我使用的是 Mac OS X 10.9.2 和 sbt 0.13.3-SNAPSHOT(根据源代码构建)，Java 8和 sbt-proguard 0.2.2 插件.

I'm on Mac OS X 10.9.2 and sbt 0.13.3-SNAPSHOT (built from the sources), Java 8 and sbt-proguard 0.2.2 plugin.

sbt 0.13.3-SNAPSHOT

[jacek]> sbtVersion
[info] 0.13.3-SNAPSHOT

Java 8

$ /Library/Java/JavaVirtualMachines/jdk1.8.0.jdk/Contents/Home/bin/java -version
java version "1.8.0"
Java(TM) SE Runtime Environment (build 1.8.0-b132)
Java HotSpot(TM) 64-Bit Server VM (build 25.0-b70, mixed mode)

project/plugins.sbt

addSbtPlugin("com.typesafe.sbt" % "sbt-proguard" % "0.2.2")

当我在 sbt shell 中运行 proguard:proguard 时，它发生了以下异常:

When I ran proguard:proguard in sbt shell it blew up with the following exception:

[sbt-updates]> show proguard:proguard
[info] ProGuard, version 4.9
[info] Reading program directory [/Users/jacek/oss/sbt-updates/target/scala-2.10/sbt-0.13/classes] (filtered)
[info] Reading program jar [/Users/jacek/.ivy2/cache/org.scalaz/scalaz-concurrent_2.10/bundles/scalaz-concurrent_2.10-7.1.0-M6.jar] (filtered)
[info] Reading program jar [/Users/jacek/.sbt/boot/scala-2.10.3/lib/scala-library.jar] (filtered)
[info] Reading program jar [/Users/jacek/.ivy2/cache/org.scalaz/scalaz-core_2.10/bundles/scalaz-core_2.10-7.1.0-M6.jar] (filtered)
[info] Reading program jar [/Users/jacek/.ivy2/cache/org.scalaz/scalaz-effect_2.10/bundles/scalaz-effect_2.10-7.1.0-M6.jar] (filtered)
[info] Reading library jar [/Library/Java/JavaVirtualMachines/jdk1.8.0.jdk/Contents/Home/jre/lib/rt.jar]
[error] Error: Can't read [/Library/Java/JavaVirtualMachines/jdk1.8.0.jdk/Contents/Home/jre/lib/rt.jar] (Can't process class [apple/applescript/AppleScriptEngine.class] (Unsupported class version number [52.0] (maximum 51.0, Java 1.7)))
[trace] Stack trace suppressed: run last proguard:proguard for the full output.
[error] (proguard:proguard) Proguard failed with exit code [1]
[error] Total time: 16 s, completed Apr 19, 2014 2:27:56 PM

为什么会是错误的原因?

Why could be the reason for the error?

推荐答案

ProGuard 和 sbt-proguard 似乎还不支持 Java 8 并更改脚本中使用的 Java 版本启动 sbt 有帮助.

It appears that ProGuard and hence sbt-proguard don't support Java 8 yet and changing the version of Java used in the script to launch sbt helped.

[sbt-updates]> show proguard:proguard
[info] Compiling 8 Scala sources to /Users/jacek/oss/sbt-updates/target/scala-2.10/sbt-0.13/classes...
[warn] there were 6 feature warning(s); re-run with -feature for details
[warn] one warning found
[info] ProGuard, version 4.9
[info] Reading program directory [/Users/jacek/oss/sbt-updates/target/scala-2.10/sbt-0.13/classes] (filtered)
[info] Reading program jar [/Users/jacek/.ivy2/cache/org.scalaz/scalaz-concurrent_2.10/bundles/scalaz-concurrent_2.10-7.1.0-M6.jar] (filtered)
...

这适用于以下版本的 Java 7:

This is with the following version of Java 7:

$ /Library/Java/JavaVirtualMachines/jdk1.7.0_51.jdk/Contents/Home/bin/java -version
java version "1.7.0_51"
Java(TM) SE Runtime Environment (build 1.7.0_51-b13)
Java HotSpot(TM) 64-Bit Server VM (build 24.51-b03, mixed mode)

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