ERROR org.hibernate.util.JDBCExceptionReport Communications link failure【解决方法】

今天爱分享给大家带来ERROR org.hibernate.util.JDBCExceptionReport Communications link failure【解决方法】，希望能够帮助到大家。
原项目用的是mysql 5.7，后调整为mysql 8.0后，数据库驱动有问题，可按需调整pom文件。

        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
            <version>8.0.20</version>
        </dependency>

但调整驱动后，发现java.net.ConnectException: Connection timed out: connect，以及 ERROR (org.hibernate.util.JDBCExceptionReporter:101)- Communications link failure

具体报错如下：

The last packet sent successfully to the server was 0 milliseconds ago. The driver has not received any packets from the server.
    at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
    at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:62)
    at sun.reflect.DelegatingConstructorAccessorImpl.__newInstance(DelegatingConstructorAccessorImpl.java:45)
    at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45009)
    at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45012)
    at java.lang.reflect.Constructor.newInstance(Constructor.java:423)
    at com.mysql.cj.exceptions.ExceptionFactory.createException(ExceptionFactory.java:61)
    at com.mysql.cj.exceptions.ExceptionFactory.createException(ExceptionFactory.java:105)
    at com.mysql.cj.exceptions.ExceptionFactory.createException(ExceptionFactory.java:151)
    at com.mysql.cj.exceptions.ExceptionFactory.createCommunicationsException(ExceptionFactory.java:167)
    at com.mysql.cj.protocol.a.NativeSocketConnection.connect(NativeSocketConnection.java:91)
    at com.mysql.cj.NativeSession.connect(NativeSession.java:144)
    at com.mysql.cj.jdbc.ConnectionImpl.connectOneTryOnly(ConnectionImpl.java:956)
    at com.mysql.cj.jdbc.ConnectionImpl.createNewIO(ConnectionImpl.java:826)
    ... 9 more
Caused by: java.net.ConnectException: Connection timed out: connect
    at java.net.DualStackPlainSocketImpl.connect0(Native Method)
    at java.net.DualStackPlainSocketImpl.socketConnect(DualStackPlainSocketImpl.java:79)
    at java.net.AbstractPlainSocketImpl.doConnect(AbstractPlainSocketImpl.java:350)
    at java.net.AbstractPlainSocketImpl.connectToAddress(AbstractPlainSocketImpl.java:206)
    at java.net.AbstractPlainSocketImpl.connect(AbstractPlainSocketImpl.java:188)
    at java.net.PlainSocketImpl.connect(PlainSocketImpl.java:172)
    at java.net.SocksSocketImpl.connect(SocksSocketImpl.java:392)
    at java.net.Socket.connect(Socket.java:589)
    at com.mysql.cj.protocol.StandardSocketFactory.connect(StandardSocketFactory.java:155)
    at com.mysql.cj.protocol.a.NativeSocketConnection.connect(NativeSocketConnection.java:65)
    ... 12 more
[2020-12-25 20:18:18.403] [] [] [] [] [--]-[] WARN (org.hibernate.util.JDBCExceptionReporter:100)- SQL Error: 0, SQLState: 08S01
[2020-12-25 20:18:18.404] [] [] [] [] [--]-[] ERROR (org.hibernate.util.JDBCExceptionReporter:101)- 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.
[2020-12-25 20:18:18.405] [] [] [] [] [--]-[] WARN (org.hibernate.util.JDBCExceptionReporter:100)- SQL Error: 0, SQLState: 08S01
[2020-12-25 20:18:18.406] [] [] [] [] [--]-[] ERROR (org.hibernate.util.JDBCExceptionReporter:101)- 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.

原因分析：

mysql存在一项属性“wait_timeout”,默认值为28800秒(8小时)，
其意思为mysql的一个connection空闲时间超过8小时，mysql会自动断开该连接。
由于dbcp没有检验该connection是否有效，所以用其进行数据操作便会出现异常。

解决办法为：

调整/etc/my.cnf 数据库配置文件，增加以下配置：

interactive_timeout = 31536000
wait_timeout = 31536000

然后重启mysql。

service restart mysql

我用的是docker ，重启命令为：

docker restart mysql