1.download dmg
2.double click
3.java -version
4.get path
/usr/libexec/java_home -V
command+c
/Library/Java/JavaVirtualMachines/jdk1.8.0_151.jdk/Contents/Home
5.environment
sudo vim /etc/profile
JAVA_HOME="/Library/Java/JavaVirtualMachines/jdk1.8.0_151.jdk/Contents/Home"
export JAVA_HOME
CLASS_PATH="$JAVA_HOME/lib"
PATH=".$PATH:$JAVA_HOME/bin”
6.source /etc/profile