mysql-使用druid连接池连接数据库，出现了以下问题，忘各位大神解答

com.mysql.jdbc.exceptions.jorg.apache.ibatis.exceptions.PersistenceException:

Error updating database. Cause: com.mysql.jdbc.exceptions.jdbc4.CommunicationsException: 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.

Cause: com.mysql.jdbc.exceptions.jdbc4.CommunicationsException: 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.

请各位大神帮帮小弟我，这是出现什么问题