Establishing SSL connection without server's identity verification is not recommended.

WARN: Establishing SSL connection without server’s identity verification is not recommended. According to MySQL 5.5.45+, 5.6.26+ and 5.7.6+ requirements SSL connection must be established by default if explicit option isn’t set. For compliance with existing applications not using SSL the verifyServerCertificate property is set to ‘false’. You need either to explicitly disable SSL by setting useSSL=false, or set useSSL=true and provide truststore for server certificate verification.

只是做一个测试的话，在连接后添加一个useSSL=false即可

jdbc:mysql://localhost:3306/test?useSSL=false

MYSQL:WARN: Establishing SSL connection without server’s identity verification is not recommended.