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.

通信异常：通信链路故障

最后一个成功发送到服务器的数据包是0毫秒前。驱动程序尚未从服务器接收到任何数据包。

2023-11-08 11:08:46.788 ERROR 326746 --- [LogReportHelper] com.zaxxer.hikari.pool.HikariPool        : HikariPool-1 - Exception during
 pool initialization.

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.
   at com.mysql.cj.jdbc.exceptions.SQLError.createCommunicationsException(SQLError.java:174) ~[mysql-connector-java-8.0.17.jar!/:8.0.
17]
   at com.mysql.cj.jdbc.exceptions.SQLExceptionsMapping.translateException(SQLExceptionsMapping.java:64) ~[mysql-connector-java-8.0.1
7.jar!/:8.0.17]
   at com.mysql.cj.jdbc.ConnectionImpl.createNewIO(ConnectionImpl.java:827) ~[mysql-connector-java-8.0.17.jar!/:8.0.17]
   at com.mysql.cj.jdbc.ConnectionImpl.<init>(ConnectionImpl.java:447) ~[mysql-connector-java-8.0.17.jar!/:8.0.17]
   at com.mysql.cj.jdbc.ConnectionImpl.getInstance(ConnectionImpl.java:237) ~[mysql-connector-java-8.0.17.jar!/:8.0.17]
   at com.mysql.cj.jdbc.NonRegisteringDriver.connect(NonRegisteringDriver.java:199) ~[mysql-connector-java-8.0.17.jar!/:8.0.17]
   at com.zaxxer.hikari.util.DriverDataSource.getConnection(DriverDataSource.java:136) ~[HikariCP-3.2.0.jar!/:na]
   at com.zaxxer.hikari.pool.PoolBase.newConnection(PoolBase.java:369) ~[HikariCP-3.2.0.jar!/:na]
   at com.zaxxer.hikari.pool.PoolBase.newPoolEntry(PoolBase.java:198) ~[HikariCP-3.2.0.jar!/:na]
   at com.zaxxer.hikari.pool.HikariPool.createPoolEntry(HikariPool.java:467) [HikariCP-3.2.0.jar!/:na]
   at com.zaxxer.hikari.pool.HikariPool.checkFailFast(HikariPool.java:541) [HikariCP-3.2.0.jar!/:na]
   at com.zaxxer.hikari.pool.HikariPool.<init>(HikariPool.java:115) [HikariCP-3.2.0.jar!/:na]
   at com.zaxxer.hikari.HikariDataSource.getConnection(HikariDataSource.java:112) [HikariCP-3.2.0.jar!/:na]
   at com.zaxxer.hikari.HikariDataSource$$FastClassBySpringCGLIB$$eeb1ae86.invoke(<generated>) [HikariCP-3.2.0.jar!/:na]
   at org.springframework.cglib.proxy.MethodProxy.invoke(MethodProxy.java:218) [spring-core-5.1.14.RELEASE.jar!/:5.1.14.RELEASE]
   at org.springframework.aop.framework.CglibAopProxy$CglibMethodInvocation.invokeJoinpoint(CglibAopProxy.java:750) [spring-aop-5.1.1
4.RELEASE.jar!/:5.1.14.RELEASE]
   at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:163) [spring-aop-5.1.14.RE
LEASE.jar!/:5.1.14.RELEASE]
   at org.springframework.aop.support.DelegatingIntroductionInterceptor.doProceed(DelegatingIntroductionInterceptor.java:136) [spring
-aop-5.1.14.RELEASE.jar!/:5.1.14.RELEASE]
   at org.springframework.aop.support.DelegatingIntroductionInterceptor.invoke(DelegatingIntroductionInterceptor.java:124) [spring-ao
p-5.1.14.RELEASE.jar!/:5.1.14.RELEASE]
   at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:186) [spring-aop-5.1.14.RE
LEASE.jar!/:5.1.14.RELEASE]
   at org.springframework.aop.framework.CglibAopProxy$DynamicAdvisedInterceptor.intercept(CglibAopProxy.java:689) [spring-aop-5.1.14.
RELEASE.jar!/:5.1.14.RELEASE]
   at com.zaxxer.hikari.HikariDataSource$$EnhancerBySpringCGLIB$$27355ba9.getConnection(<generated>) [HikariCP-3.2.0.jar!/:na]
   at org.springframework.jdbc.datasource.DataSourceUtils.fetchConnection(DataSourceUtils.java:158) [spring-jdbc-5.1.14.RELEASE.jar!/
:5.1.14.RELEASE]
   at org.springframework.jdbc.datasource.DataSourceUtils.doGetConnection(DataSourceUtils.java:116) [spring-jdbc-5.1.14.RELEASE.jar!/
:5.1.14.RELEASE]
   at org.springframework.jdbc.datasource.DataSourceUtils.getConnection(DataSourceUtils.java:79) [spring-jdbc-5.1.14.RELEASE.jar!/:5.
1.14.RELEASE]
   at org.mybatis.spring.transaction.SpringManagedTransaction.openConnection(SpringManagedTransaction.java:80) [mybatis-spring-2.0.3.
jar!/:2.0.3]
   at org.mybatis.spring.transaction.SpringManagedTransaction.getConnection(SpringManagedTransaction.java:67) [mybatis-spring-2.0.3.j
ar!/:2.0.3]
   at org.apache.ibatis.executor.BaseExecutor.getConnection(BaseExecutor.java:336) [mybatis-3.5.3.jar!/:3.5.3]
   at org.apache.ibatis.executor.SimpleExecutor.prepareStatement(SimpleExecutor.java:86) [mybatis-3.5.3.jar!/:3.5.3]
   at org.apache.ibatis.executor.SimpleExecutor.doQuery(SimpleExecutor.java:62) [mybatis-3.5.3.jar!/:3.5.3]
   at org.apache.ibatis.executor.BaseExecutor.queryFromDatabase(BaseExecutor.java:324) [mybatis-3.5.3.jar!/:3.5.3]
   at org.apache.ibatis.executor.BaseExecutor.query(BaseExecutor.java:156) [mybatis-3.5.3.jar!/:3.5.3]
   at org.apache.ibatis.executor.CachingExecutor.query(CachingExecutor.java:109) [mybatis-3.5.3.jar!/:3.5.3]
   at org.apache.ibatis.executor.CachingExecutor.query(CachingExecutor.java:83) [mybatis-3.5.3.jar!/:3.5.3]
   at org.apache.ibatis.session.defaults.DefaultSqlSession.selectList(DefaultSqlSession.java:147) [mybatis-3.5.3.jar!/:3.5.3]
   at org.apache.ibatis.session.defaults.DefaultSqlSession.selectList(DefaultSqlSession.java:140) [mybatis-3.5.3.jar!/:3.5.3]
   at org.apache.ibatis.session.defaults.DefaultSqlSession.selectOne(DefaultSqlSession.java:76) [mybatis-3.5.3.jar!/:3.5.3]
   at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[na:1.8.0_342]
   at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) ~[na:1.8.0_342]
   at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) ~[na:1.8.0_342]
   at java.lang.reflect.Method.invoke(Method.java:498) ~[na:1.8.0_342]
   at org.mybatis.spring.SqlSessionTemplate$SqlSessionInterceptor.invoke(SqlSessionTemplate.java:426) [mybatis-spring-2.0.3.jar!/:2.0
.3]

网络问题?

可能是网络问题 ,导致连接不上，ping一下MySQL所在主机的IP

没有问题！

端口问题？

依然没有问题！

数据设置wait_timeout时间

数据设置wait_timeout时间，在默认配置不改变的情况下，如果连续8小时内都没有访问数据库的操作，再次访问mysql数据库的时候，mysql数据库会拒绝访问。

查看一下

show global variables like 'wait_timeout';

show global variables like 'interactive_timeout';

把时间设置长点

设置7天

set global wait_timeout=604800;
set global interactive_timeout=604800;

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