hive实例化schema报错： Failed to get schema version._org.apache.hadoop.hive.metastore.hivemetaexception

具体报错：

Metastore connection URL:     jdbc:mysql://hm02:3306/hive?createDatabaseIfNotExist=true
Metastore Connection Driver :     com.mysql.cj.jdbc.Driver
Metastore connection User:     hive
org.apache.hadoop.hive.metastore.HiveMetaException: Failed to get schema version.
Underlying cause: com.mysql.cj.jdbc.exceptions.CommunicationsException : Communications link failure
 
The last packet sent successfully to the server was 0 milliseconds ago. The driver has not received any packets from the server.
SQL Error code: 0
Use --verbose for detailed stacktrace.
*** schemaTool failed ***

原因及解决方案： 

说来惭愧，自己都想打自己（这个问题困扰了我一整天）&#