### Error querying database. Cause: com.mysql.jdbc.exceptions.jdbc4.MySQLNonTransientConnectionException: No operations allowed after connection closed.
网上查了下，由于使用了默认配置，空闲超过8小时，自动断开该连接
我使用的是mybatis的默认连接池，于是把该配的，都配置上。datasource的属性，可参考mybatis官方文档
<environment id="env_stg">
<transactionManager type="JDBC" />
<dataSource type="POOLED">
<property name="driver" value="${driver}" />
<property name="url" value="${url_stg}" />
<property name="username" value="${username}" />
<property name="password" value="${password}" />
<property name="poolMaximumActiveConnections" value="20"/>
<property name="poolMaximumIdleConnections" value="5"/>
<!-- MySQLNonTransientConnectionException: No operations allowed after connection closed -->
<property name="poolPingQuery" value="select 1"/>
<property name="poolPingEnabled" value="true"/>
<!-- 对于空闲的连接一个小时检查一次 -->
<property name="poolPingConnectionsNotUsedFor" value="3600000"/>
</dataSource>
</environment>
