在macOS 上添加 JAVA_HOME 环境变量

If you are planing to develop Java Apps on your Mac, you may have to set $JAVA_HOME environment variable.

Install the latest Java Virtual Machine

Go to How to install JDK on Mac OS X to install a new Java Virtual Machine. Download the latest Java JDK package from Oracle.

Check Java Virtual Machines

List directories in the following root -> /Library/Java/JavaVirtualMachines

$ ls -l /Library/Java/JavaVirtualMachines
drwxr-xr-x  3 root  wheel  102 23 dic 20:36 jdk1.8.0_66.jdk
drwxr-xr-x  3 root  wheel  102 21 mar 14:20 jdk1.8.0_74.jdk

And the version for java will be the latest.

$ java -version
java version "1.8.0_74"
Java(TM) SE Runtime Environment (build 1.8.0_74-b02)
Java HotSpot(TM) 64-Bit Server VM (build 25.74-b02, mixed mode)

Set JAVA_HOME environment variable

Open your terminal, and create .bash_profile file if it does not exist.

vim .bash_profile

And write the following:

export JAVA_HOME=$(/usr/libexec/java_home)

Refresh the environment variables by running the following command, and check the $JAVA_HOME value:

$ source .bash_profile
$ echo $JAVA_HOME
/Library/Java/JavaVirtualMachines/jdk1.8.0_74.jdk/Contents/Home

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简单的说就是先安装JDK，然后找到 .bash_Profile (因为我不会用vim)。
在最后一行添加

export JAVA_HOME=$(/usr/libexec/java_home)

然后在命令行里输入 
source .bash_profile

然后查看结果： 

echo $JAVA_HOME