org.apache.ibatis.exceptions.PersistenceException: ### Error querying database. Cause: com.mysql.cj.jdbc.exceptions.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. ### The error may exist in data/article.xml ### The error may involve com.xialxl.service.Article_Query ### The error occurred while executing a query ### Cause: com.mysql.cj.jdbc.exceptions.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.