从Oracle官网下载安装文件
https://www.oracle.com/java/technologies/javase-downloads.html
解压
tar zxf /home/yangning/Downloads/jdk-15.0.2_linux-x64_bin.tar.gz -C /jdk15/
配置环境变量
sudo gedit /etc/profile
export JAVA15_HOME=/jdk15/jdk-15.0.2
export PATH=$PATH:$JAVA15_HOME/bin
source /etc/profile