1.到java官网下载jdk-9.0.1的linux版
http://www.oracle.com/technetwork/java/javase/downloads/index.html
2.
解压到/usr/lib/jvm/目录下,我的是/usr/lib/jvm/jdk-9.0.1
3.
sudo update-alternatives --install /usr/bin/java java /usr/lib/jvm/jdk-9.0.1/bin/java 1
4.
sudo update-alternatives --install /usr/bin/javac javac /usr/lib/jvm/jdk-9.0.1/bin/javac 1
5.
sudo update-alternatives --config java
选择jdk-9.0.1对应的号码,回车
6.
sudo update-alternatives --config javac
选择jdk-9.0.1对应的号码,回车
7.设置环境变量
echo $JAVA_HOME //查看原先的值
sudo echo export JAVA_HOME="/usr/lib/jvm/jdk-9.0.1/" >> ~/.bashrc //设置环境变量
source ~/.bashrc //使环境变量生效
echo $JAVA_HOME //查看环境变量是否设置成功
8.检查
执行java -version和javac -version
查看是否升级成功