更新源
sudo apt-get update
安裝默認JRE/JDK
sudo apt-get install default-jre
sudo apt-get install default-jdk
安裝oracle JDK
sudo apt-get install software-properties-common
sudo add-apt-repository ppa:webupd8team/java
sudo apt-get update
安裝JDK8
sudo apt-get install oracle-java8-installer
java -version