我试过这个命令：
keytool -keypasswd -keystore mykeystore.jks -alias key0
我得到了这个：
keytool error: java.lang.UnsupportedOperationException: -keypasswd commands not supported if -storetype is PKCS12
然而输出：
keytool -list -keystore mykeystore.jks -v
如下：
Enter keystore password:
Keystore type: JKS
Keystore provider: SUN
Your keystore contains 1 entry
Alias name: key0
Creation date: 21 Dec 2017
Entry type: PrivateKeyEntry
Certificate chain length: 1
Certificate[1]:
...