报错：Exception in thread "main" com.mysql.cj.jdbc.exceptions.CommunicationsException: Communications link failure
更换 mysql-connector-java-8.0.11.jar 为 mysql-connector-java-8.0.16.jar，
下载位置：https://mvnrepository.com/artifact/mysql/mysql-connector-java/8.0.16
可能是 mysql-connector-java-8.0.11.jar 存在BUG，新版本8.0.16中被解决。
Java连接MySQL报错：CommunicationsException: Communications link failure
原文：https://www.cnblogs.com/jtzhang163/p/10891569.html