转自 http://ningandjiao.iteye.com/blog/2045955?utm_source=tuicool&utm_medium=referral

1.首先安装所有的JDk： 
* 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 
2. 在用户目录下的bash配置文件.bashrc中配置JAVA_HOME的路径： 

export JAVA_6_HOME=/System/Library/Java/JavaVirtualMachines/1.6.0.jdk/Contents/Home
export JAVA_7_HOME=/Library/Java/JavaVirtualMachines/jdk1.7.0.jdk/Contents/Home
export JAVA_8_HOME=/Library/Java/JavaVirtualMachines/jdk1.8.0.jdk/Contents/Home
export JAVA_HOME=$JAVA_7_HOME

3.创建alias命令动态切换JAVA_HOME的配置 

alias jdk8=‘export JAVA_HOME=$JAVA_8_HOME‘
alias jdk7=‘export JAVA_HOME=$JAVA_7_HOME‘
alias jdk6=‘export JAVA_HOME=$JAVA_6_HOME‘

*验证* source .bash_profile 

CNxnliu:Versions xnliu$ java -version
java version "1.6.0_65"
Java(TM) SE Runtime Environment (build 1.6.0_65-b14-462-11M4609)
Java HotSpot(TM) 64-Bit Server VM (build 20.65-b04-462, mixed mode)
CNxnliu:Versions xnliu$ jdk8
CNxnliu:Versions xnliu$ java -version
java version "1.8.0"
Java(TM) SE Runtime Environment (build 1.8.0-b132)
Java HotSpot(TM) 64-Bit Server VM (build 25.0-b70, mixed mode)
CNxnliu:Versions xnliu$