solution:
Database settings: utf8mb4 (which is most of the online solutions)
But if the set is not successful, check the version of the database connection
<dependency>
<groupId> MySQL </ groupId>
<artifactId> MySQL-Connector-the Java </ artifactId>
<Version> 8.0.16 </ Version>
<scope> Runtime </ scope>
</ dependency>
Local database version before the author 8.0, did not find problems, but the online database version 5.7,
you need to modify the database connection version can be resolved