>root cause
>com.MysqL.jdbc.exceptions.jdbc4.MysqLNonTransientConnectionException:
No operations allowed after connection closed.
Connection was implicitly closed due to underlying exception/error:
** BEGIN NESTED EXCEPTION **
>com.MysqL.jdbc.exceptions.jdbc4.CommunicationsException
MESSAGE: Communications link failure
>Last packet sent to the server was 43 ms ago.
>STACKTRACE:
>com.MysqL.jdbc.exceptions.jdbc4.CommunicationsException: Communications link failure
很清楚，根本原因是Communications link failure。
尝试ping您的数据库服务器，看看是否能够连接。 否则解决网络问题，然后连接。没有其他选择。
您可以减轻ping数据库服务器的负担，以检查连接可用性。
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