HDFS集群启动start-dfs.sh报错

[root@master sbin]# start-dfs.sh
Starting namenodes on [master]
master: Error: JAVA_HOME is not set and could not be found.
The authenticity of host ‘localhost (::1)‘ can‘t be established.
ECDSA key fingerprint is e8:5a:7d:5c:e3:f7:57:4a:96:c2:65:d6:e9:39:d0:7d.
Are you sure you want to continue connecting (yes/no)? yes
localhost: Warning: Permanently added ‘localhost‘ (ECDSA) to the list of known hosts.
localhost: Error: JAVA_HOME is not set and could not be found.
Starting secondary namenodes [0.0.0.0]
The authenticity of host ‘0.0.0.0 (0.0.0.0)‘ can‘t be established.
ECDSA key fingerprint is e8:5a:7d:5c:e3:f7:57:4a:96:c2:65:d6:e9:39:d0:7d.
Are you sure you want to continue connecting (yes/no)? ^C0.0.0.0: Host key verification failed.