个人博客地址：Mac OS JAVA_HOME设置 | 一张假钞的真实世界

在MacOS上使用DMG文件安装了Jdk8 之后，在默认路径下找不到JDK的HOME路径：

$ which java
/usr/bin/java
$ ls -l /usr/bin/java
lrwxr-xr-x  1 root  wheel  74 12  6  2015 /usr/bin/java -> /System/Library/Frameworks/JavaVM.framework/Versions/Current/Commands/java
$ ls -l /System/Library/Frameworks/JavaVM.framework/Versions
total 8
drwxr-xr-x  10 root  wheel  340  5  9 20:45 A
lrwxr-xr-x   1 root  wheel    1 12  6  2015 Current -> A
$ ls -l /System/Library/Frameworks/JavaVM.framework/Versions/A/
total 80
drwxr-xr-x  47 root  wheel    1598 10 18  2015 Commands
drwxr-xr-x   4 root  wheel     136 10 18  2015 Frameworks
drwxr-xr-x  14 root  wheel     476  8  2  2015 Headers
drwxr-xr-x   3 root  wheel     102  8 23  2015 JavaPluginCocoa.bundle
-rwxr-xr-x   1 root  wheel  109488 10 18  2015 JavaVM
drwxr-xr-x   3 root  wheel     102  8  2  2015 Modules
drwxr-xr-x  45 root  wheel    1530 10 18  2015 Resources
drwxr-xr-x   3 root  wheel     102  8 23  2015 _CodeSignature

在MacOS下可以使用/usr/libexec/java_home命令来定位JAVA_HOME：

$ /usr/libexec/java_home
/Library/Java/JavaVirtualMachines/jdk1.8.0_91.jdk/Contents/Home

设置JAVA_HOME：

export JAVA_HOME=`/usr/libexec/java_home`

检查JAVA_HOME：

$ echo $JAVA_HOME
/Library/Java/JavaVirtualMachines/jdk1.8.0_91.jdk/Contents/Home

如果安装了多个版本的JDK，可以使用-V命令选项列出所有版本的JAVA_HOME：

$ /usr/libexec/java_home -V
Matching Java Virtual Machines (1):1.8.0_91, x86_64:	"Java SE 8"	/Library/Java/JavaVirtualMachines/jdk1.8.0_91.jdk/Contents/Home/Library/Java/JavaVirtualMachines/jdk1.8.0_91.jdk/Contents/Home