问题
I know there is version conflict. Just want someone to tell me how to resolve it. In previous stackoverflow post no one tells the solution.
Versions: Ubuntu: 12.04.1 LTS java: 1.6.0_24 (OpenJDK) javac: 1.7.0_07 (OpenJDK)
haider@haider-desktop:~/Documents/projects/java-projects/mytestapp$ play
[info] Loading project definition from /home/haider/Documents/projects/java-projects/mytestapp/project
[info] Set current project to mytestapp (in build file:/home/haider/Documents/projects/java-projects/mytestapp/)
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play! 2.0.4, http://www.playframework.org
> Type "help play" or "license" for more information.
> Type "exit" or use Ctrl+D to leave this console.
[mytestapp] $ run
--- (Running the application from SBT, auto-reloading is enabled) ---
[info] play - Listening for HTTP on port 9000...
(Server started, use Ctrl+D to stop and go back to the console...)
[info] Compiling 5 Scala sources and 2 Java sources to /home/haider/Documents/projects/libraries/play-2.0.4/samples/java/helloworld/target/scala-2.9.1/classes...
[warn] Problem processing dependencies of source /home/haider/Documents/projects/libraries/play-2.0.4/samples/java/helloworld/target/scala-2.9.1/src_managed/main/controllers/routes.java : java.lang.UnsupportedClassVersionError: controllers/routes : Unsupported major.minor version 51.0
[warn] Problem processing dependencies of source /home/haider/Documents/projects/libraries/play-2.0.4/samples/java/helloworld/target/scala-2.9.1/src_managed/main/controllers/routes.java : java.lang.UnsupportedClassVersionError: controllers/routes$javascript : Unsupported major.minor version 51.0
[warn] Problem processing dependencies of source /home/haider/Documents/projects/libraries/play-2.0.4/samples/java/helloworld/target/scala-2.9.1/src_managed/main/controllers/routes.java : java.lang.UnsupportedClassVersionError: controllers/routes : Unsupported major.minor version 51.0
[warn] Problem processing dependencies of source /home/haider/Documents/projects/libraries/play-2.0.4/samples/java/helloworld/target/scala-2.9.1/src_managed/main/controllers/routes.java : java.lang.UnsupportedClassVersionError: controllers/routes$ref : Unsupported major.minor version 51.0
[warn] Problem processing dependencies of source /home/haider/Documents/projects/libraries/play-2.0.4/samples/java/helloworld/target/scala-2.9.1/src_managed/main/controllers/routes.java : java.lang.UnsupportedClassVersionError: controllers/routes$javascript : Unsupported major.minor version 51.0
[warn] Problem processing dependencies of source /home/haider/Documents/projects/libraries/play-2.0.4/samples/java/helloworld/target/scala-2.9.1/src_managed/main/controllers/routes.java : java.lang.UnsupportedClassVersionError: controllers/routes : Unsupported major.minor version 51.0
[warn] Problem processing dependencies of source /home/haider/Documents/projects/libraries/play-2.0.4/samples/java/helloworld/target/scala-2.9.1/src_managed/main/controllers/routes.java : java.lang.UnsupportedClassVersionError: controllers/routes$ref : Unsupported major.minor version 51.0
[warn] Error reading API from class file : java.lang.UnsupportedClassVersionError: controllers/routes$javascript : Unsupported major.minor version 51.0
[warn] Error reading API from class file : java.lang.UnsupportedClassVersionError: controllers/routes : Unsupported major.minor version 51.0
[warn] Error reading API from class file : java.lang.UnsupportedClassVersionError: controllers/routes$ref : Unsupported major.minor version 51.0
[warn] Problem processing dependencies of source /home/haider/Documents/projects/libraries/play-2.0.4/samples/java/helloworld/app/controllers/Application.java : java.lang.UnsupportedClassVersionError: controllers/Application$Hello : Unsupported major.minor version 51.0
[warn] Problem processing dependencies of source /home/haider/Documents/projects/libraries/play-2.0.4/samples/java/helloworld/app/controllers/Application.java : java.lang.UnsupportedClassVersionError: controllers/Application : Unsupported major.minor version 51.0
[warn] Problem processing dependencies of source /home/haider/Documents/projects/libraries/play-2.0.4/samples/java/helloworld/app/controllers/Application.java : java.lang.UnsupportedClassVersionError: controllers/Application$Hello : Unsupported major.minor version 51.0
[warn] Problem processing dependencies of source /home/haider/Documents/projects/libraries/play-2.0.4/samples/java/helloworld/app/controllers/Application.java : java.lang.UnsupportedClassVersionError: controllers/Application : Unsupported major.minor version 51.0
[warn] Error reading API from class file : java.lang.UnsupportedClassVersionError: controllers/Application$Hello : Unsupported major.minor version 51.0
[warn] Error reading API from class file : java.lang.UnsupportedClassVersionError: controllers/Application : Unsupported major.minor version 51.0
[info] play - Application started (Dev)
回答1:
You are using different JDK versions to compile and run the application. You say that:
java: 1.6.0_24 (OpenJDK)
javac: 1.7.0_07 (OpenJDK)
So your compiler (javac) is a newer release than the java command, which means the second can't run your compiled files. You must use only 1 version of the JDK (same for java and javac)
回答2:
On Ubuntu to change Java version for both compiling and running you need to call:
sudo update-alternatives --config javac
and
sudo update-alternatives --config java
回答3:
A better solution is to change the target version, so you could compile to 1.6 from 1.7 like this: How can I set the javac compile version for Play Framework 2.0 to prevent "Unsupported major.minor version"?
Put this in your Build.scala:
val main = play.Project(appName, appVersion, appDependencies).settings(
// Force compilation in java 1.6
javacOptions in Compile ++= Seq("-source", "1.6", "-target", "1.6")
)
来源：https://stackoverflow.com/questions/12722381/unsupported-major-minor-version-51-0-while-running-play-framework