如果用bash，修改~/.bash_profile 或 ~/.profile；
如果用zsh，修改～/.zshrc
修改这些文件之后，重修打开terminal，配置不会丢
首先确保已经安装了jdk：
## check the present running java
which java ## check java version
java -version 以zsh为例：
## check all the available jdk
2 /usr/libexec/java_home -V
3
4 ## check the top jdk
5 /usr/libexec/java_home
6
7 ## check some jdk (eg. version 1.7)
8 /usr/libexec/java_home -v 1.7
9
10 ## edit .zshrc to set java_home variable
11 vim ~/.zshrc
12
13 ## add the following line into the file
14 export JAVA_HOME=$(/usr/libexec/java_home)
15
16 ## you can also use the following line to set the variable, which is not recommended, only for older mac os.
17 ## export JAVA_HOME=/System/Library/Java/JavaVirtualMachines/1.6.0.jdk/Contents/Home
18
19 ##let the configuration in .zshrc take effect
20 source ~/.zshrc
21
22 ## check if configure succeed
23 echo $JAVA_HOME