Communications link failure ，The last packet successfully received from the server was 18,903 millis

今天开发环境出现连接数据报以下错误，错误信息如下：

The last packet successfully received from the server was 18,903 milliseconds ago.  
The last packet sent successfully to the server was 18,901 milliseconds ago.; 
nested exception is com.mysql.jdbc.exceptions.jdbc4.CommunicationsException: Communications link failure


The last packet successfully received from the server was 18,903 milliseconds ago.  The last packet sent successfully to the server was 18,901 milliseconds ago.
  at org.springframework.jdbc.support.SQLExceptionSubclassTranslator.doTranslate(SQLExceptionSubclassTranslator.java:98) ~[spring-jdbc-4.2.7.RELEASE.jar:4.2.7.RELEASE]
  at org.springframework.jdbc.support.AbstractFallbackSQLExceptionTranslator.translate(AbstractFallbackSQLExceptionTranslator.java:73) ~[spring-jdbc-4.2.7.RELEASE.jar:4.2.7.RELEASE]
  at org.springframework.jdbc.support.AbstractFallbackSQLExceptionTranslator.translate(AbstractFallbackSQLExceptionTranslator.java:81) ~[spring-jdbc-4.2.7.RELEASE.jar:4.2.7.RELEASE]
  at org.mybatis.spring.MyBatisExceptionTranslator.translateExceptionIfPossible(MyBatisExceptionTranslator.java:75) ~[mybatis-spring-1.3.0.jar:1.3.0]
  at org.mybatis.spring.SqlSessionTemplate$SqlSessionInterceptor.invoke(SqlSessionTemplate.java:447) ~[mybatis-spring-1.3.0.jar:1.3.0]
  at com.sun.proxy.$Proxy97.selectList(Unknown Source) ~[na:na]
  at org.mybatis.spring.SqlSessionTemplate.selectList(SqlSessionTemplate.java:231) ~[mybatis-spring-1.3.0.jar:1.3.0]
  at org.apache.ibatis.binding.MapperMethod.executeForMany(MapperMethod.java:128) ~[mybatis-3.4.0.jar:3.4.0]
  at org.apache.ibatis.binding.MapperMethod.execute(MapperMethod.java:68) ~[mybatis-3.4.0.jar:3.4.0]
  at org.apache.ibatis.binding.MapperProxy.invoke(MapperProxy.java:53) ~[mybatis-3.4.0.jar:3.4.0]
  at com.sun.proxy.$Proxy117.listOfCirculationOrderBy(Unknown Source) ~[na:na]
  at com.cloud.saas.official.service.impl.CirculationServiceImpl.listOfCirculationOrderBy(CirculationServiceImpl.java:98) ~[classes/:na]
  at com.cloud.saas.official.service.impl.CirculationServiceImpl$$FastClassBySpringCGLIB$$7c31abe8.invoke() ~[classes/:na]
  at org.springframework.cglib.proxy.MethodProxy.invoke(MethodProxy.java:204) ~[spring-core-4.2.7.RELEASE.jar:4.2.7.RELEASE]
  at org.springframework.aop.framework.CglibAopProxy$CglibMethodInvocation.invokeJoinpoint(CglibAopProxy.java:720) ~[spring-aop-4.2.7.RELEASE.jar:4.2.7.RELEASE]
  at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:157) ~[spring-aop-4.2.7.RELEASE.jar:4.2.7.RELEASE]
  at org.springframework.transaction.interceptor.TransactionInterceptor$1.proceedWithInvocation(TransactionInterceptor.java:99) ~[spring-tx-4.2.7.RELEASE.jar:4.2.7.RELEASE]
  at org.springframework.transaction.interceptor.TransactionAspectSupport.invokeWithinTransaction(TransactionAspectSupport.java:281) ~[spring-tx-4.2.7.RELEASE.jar:4.2.7.RELEASE]
  at org.springframework.transaction.interceptor.TransactionInterceptor.invoke(TransactionInterceptor.java:96) ~[spring-tx-4.2.7.RELEASE.jar:4.2.7.RELEASE]
  at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:179) ~[spring-aop-4.2.7.RELEASE.jar:4.2.7.RELEASE]
  at org.springframework.aop.framework.CglibAopProxy$DynamicAdvisedInterceptor.intercept(CglibAopProxy.java:655) ~[spring-aop-4.2.7.RELEASE.jar:4.2.7.RELEASE]
  at com.cloud.saas.official.service.impl.CirculationServiceImpl$$EnhancerBySpringCGLIB$$a6c1c39a.listOfCirculationOrderBy() ~[classes/:na]
  at com.cloud.saas.official.controller.CirculationController.listOfCirculation(CirculationController.java:79) ~[classes/:na]

出现问题还是百度、Google查询，这错误还是比较常见的，出现这错误的原因：

        MySQL服务器默认的“wait_timeout”是28800秒即8小时，意味着如果一个连接的空闲时间超过8个小时，MySQL将自动断开该连接，而连接池却认为该连接还是有效的(因为并未校验连接的有效性)，当应用申请使用该连接时，就会导致上面的报错。
修改MySQL的参数了，wait_timeout最大为31536000即1年，在my.cnf中加入：

[mysqld]
wait_timeout=31536000
interactive_timeout=31536000

重启生效，需要同时修改这两个参数。

我这里是用Docker 起的mysql5.7的，所以可以直接用以下命令加入以上参数：

docker exec mysql bash -c "echo 'wait_timeout=31536000' >> /etc/mysql/mysql.conf.d/mysqld.cnf"
docker exec mysql bash -c "echo 'interactive_timeout=31536000' >> /etc/mysql/mysql.conf.d/mysqld.cnf"

docker restart mysql