Mac自带了的JDK6,安装在目录:/System/Library/Java/JavaVirtualMachines/1.6.0.jdk/
下。
JDK7,JDK8则需要自己到Oracle官网下载安装对应的版本。自己安装的JDK默认路径为:/Library/Java/JavaVirtualMachines/jdk1.8.0.jdk
export JAVA_6_HOME=/System/Library/Java/JavaVirtualMachines/1.6.0.jdk/Contents/Home