为什么closure-maven-plugin没有选择正确的Java版本？

Question

我试图编译Storm Starter与JDK 7

$ echo $JAVA_HOME                         [master] 
/opt/jdk1.7.0_80 

$ mvn -version 
Apache Maven 3.0.5 
Maven home: /usr/share/maven 
Java version: 1.7.0_80, vendor: Oracle Corporation 
Java home: /opt/jdk1.7.0_80/jre 
Default locale: en_US, platform encoding: UTF-8 
OS name: "linux", version: "3.13.0-65-generic", arch: "amd64", family: "unix" 

$ mvn clean install -DskipTests=true 
       ... 
[INFO] --- clojure-maven-plugin:1.7.1:compile (compile-clojure) @ storm-core --- 
Compiling backtype.storm.LocalDRPC to /home/incubator-storm/storm-core/target/classes 

Exception in thread "main" java.lang.UnsupportedClassVersionError: backtype/storm/ILocalDRPC : Unsupported major.minor version 51.0, compiling:(backtype/storm/LocalDRPC.clj:17:1) 
Caused by: java.lang.UnsupportedClassVersionError: backtype/storm/ILocalDRPC : Unsupported major.minor version 51.0 

据this线程，我使用的Java版本错误，我应该使用Java 7，但我的Java版本是 7.所以我的直觉是，编译时，closure-maven-plugin没有选择正确的Java版本。怎样才能让这个项目编译？

Answer 1

您需要确保$JAVA_HOME/bin（或至少1.7 java可执行文件）首先在您的PATH中，因为它是插件所使用的。

使用指向JDK 1.7的JAVA_HOME，我可以通过在我的PATH中首先将路径设置为java（JDK 1.6目录）来复制此问题。该clojure-maven-plugin代码试图确定这条道路和回落在当前环境中使用刚刚java/PATH：

private String getJavaExecutable() throws MojoExecutionException { 

    Toolchain tc = toolchainManager.getToolchainFromBuildContext("jdk", //NOI18N 
                   session); 
    if (tc != null) { 
     getLog().info("Toolchain in clojure-maven-plugin: " + tc); 
     String foundExecutable = tc.findTool("java"); 
     if (foundExecutable != null) { 
     return foundExecutable; 
     } else { 
     throw new MojoExecutionException("Unable to find 'java' executable for toolchain: " + tc); 
     } 
    } 

    return "java"; 
    }