# whereis java java: /usr/bin/java /usr/share/man/man1/java.1第二步：ls -lrt /usr/bin/java
# ls -lrt /usr/bin/java lrwxrwxrwx 1 root root 22 4月 2 2020 /usr/bin/java -> /etc/alternatives/java第三步：ls -lrt /etc/alternatives/java
# ls -lrt /etc/alternatives/java lrwxrwxrwx 1 root root 41 4月 2 2020 /etc/alternatives/java -> /usr/java/jdk1.8.0_231-amd64/jre/bin/java
定位到jdk安装地址为：/usr/java/jdk1.8.0_231-amd64
