异常解决：Caused by: com.mysql.jdbc.exceptions.jdbc4.CommunicationsException: Communications link failure
https://www.cnblogs.com/both-eyes/p/11066937.html
https://blog.csdn.net/wd2014610/article/details/81065520
https://www.bbsmax.com/A/mo5kVy24Jw/
https://www.cnblogs.com/both-eyes/p/11066937.html
https://blog.csdn.net/wd2014610/article/details/81065520
https://www.bbsmax.com/A/mo5kVy24Jw/
