journalctl -u rocketmqnamesrv.service     # View error reports

As a result, baidu is a pile, which is not used indiscriminately.

Final solution

Set according to your own Java environment variables

 ln -s /usr/local/java/jdk1.8.0_60/bin/javac /usr/bin/javac
 ln -s  /usr/local/java/jdk1.8.0_60/bin/jar /usr/bin/jar
 ln -s /usr/local/java/jdk1.8.0_60/bin/java /bin/java

Startup succeeded.