[MySql]当虚拟机的IP地址自动更换后，JDBC使用原来的配置连不上MySql数据库时所报的异常。

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.Exception in thread "main" java.lang.NullPointerException
at com.hy.ColumnSeeker.fetchAllColumns(ColumnSeeker.java:81)
at com.hy.ColumnSeeker.main(ColumnSeeker.java:139)

--END-- 2019年11月3日08:40:00