oracle 官网下载jre
https://www.java.com/en/download/linux_manual.jsp?locale=en
比如jre1.8.0_251
解压缩
复制到 usr/lib/java下
xed ~/.profile
export JAVA_HOME="/usr/lib/java/jre1.8.0_251"
export CLASSPATH="$JAVA_HOME/lib"
source ~/.profile
sudo update-alternatives --install /usr/bin/java java /usr/lib/java/jre1.8.0_251/bin/java 300
sudo update-alternatives --config java
java -version
