【发布时间】：2014-12-22 21:37:21
【问题描述】：
我从github克隆了JRuby源码，先在控制台通过mvn编译源码（JDK7）。编译成功。
然后我将整个项目加载到 netbeans(8.0) 中，并尝试编译，但它会抛出错误 "exec-maven-plugin:1.2.1:exec (invoker-generator) @ jruby-core"
cd /opt/pro/jrubysrc/jruby/core; JAVA_HOME=/opt/pro/JDK/jdk1.7.0_40 /opt/pro/netbeans-8.0.2/java/maven/bin/mvn -Dfile.encoding=utf-8 clean install
Scanning for projects...
...
--- exec-maven-plugin:1.2.1:exec (invoker-generator) @ jruby-core ---
Exception in thread "main" java.lang.UnsupportedClassVersionError: **org/jruby/anno/InvokerGenerator : Unsupported major.minor version 51.0**
at java.lang.ClassLoader.defineClass1(Native Method)
at java.lang.ClassLoader.defineClass(ClassLoader.java:643)
at java.security.SecureClassLoader.defineClass(SecureClassLoader.java:142)
at java.net.URLClassLoader.defineClass(URLClassLoader.java:277)
at java.net.URLClassLoader.access$000(URLClassLoader.java:73)
at java.net.URLClassLoader$1.run(URLClassLoader.java:212)
at java.security.AccessController.doPrivileged(Native Method)
at java.net.URLClassLoader.findClass(URLClassLoader.java:205)
at java.lang.ClassLoader.loadClass(ClassLoader.java:323)
at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:294)
at java.lang.ClassLoader.loadClass(ClassLoader.java:268)
Could not find the main class: org.jruby.anno.InvokerGenerator. Program will exit.
------------------------------------------------------------------------
Reactor Summary:
JRuby ............................................. SUCCESS [0.948s]
JRuby Core ........................................ FAILURE [1:31.125s]
JRuby Lib Setup ................................... SKIPPED
------------------------------------------------------------------------
BUILD FAILURE
------------------------------------------------------------------------
Total time: 1:32.562s
Finished at: Mon Dec 22 01:08:01 AST 2014
Final Memory: 17M/254M
------------------------------------------------------------------------
Failed to execute goal org.codehaus.mojo:exec-maven-plugin:1.2.1:exec (invoker-generator) on project jruby-core: Command execution failed. Process exited with an error: 1 (Exit value: 1) -> [Help 1]
To see the full stack trace of the errors, re-run Maven with the -e switch.
Re-run Maven using the -X switch to enable full debug logging.
For more information about the errors and possible solutions, please read the following articles:
[Help 1] http://cwiki.apache.org/confluence/display/MAVEN/MojoExecutionException
After correcting the problems, you can resume the build with the command
mvn <goals> -rf :jruby-core
JDK 仍然是 1.7。似乎某些 InvokerGenerator 是由其他非 1.7 javac 编译的。然后我清理了 ruby-core 项目，甚至手动删除了目标目录（选择项目，然后右键单击 => 选择清理和构建）。错误是一样的。
【问题讨论】：