通过自己亲自对各种方案进行测试，目前我认为能解决这个问题的最优办法是（直接贴代码）：

那么如何测试这个方案是否解决了问题？

第一、将MySQL的空闲时间设置短一些。设置方法：找到MySQL安装目录下的my.ini文件，用记事本或UE或notepad++工具打开，在[mysqld]节点中加入以下设置：

interactive_timeout=120
wait_timeout=120

设置为2分钟，网上有些只提出了设置wait_timeout即可，但我在测试时，这个设置无效，仍然是8小时，我就将interactive_timeout也设置为2分钟，我目前不知道为什么，希望有知道能分享一下。设置完毕，重启MySQL服务。

打开MySQL命了窗口，输入show variables like '%timeout%';回车，即可查看是否设置生效，如果未生效，还是28800，则检查是否同时也设置了interactive_timeout。

第二、在C3P0的配置中，我们注释掉上面贴出的配置代码，启动程序，然后打开自己编写的系统或网站等，2分钟后随便做一个与数据库有关的操作，没错，就会出现下面的异常：

com.mysql.jdbc.exceptions.jdbc4.CommunicationsException:

The last packet successfully received from the server was 661,156 milliseconds ago. The last packet sent successfully to the server was 661,157 milliseconds ago. is longer than the server configured value of 'wait_timeout'. You should consider either expiring and/or testing connection validity before use in your application, increasing the server configured values for client timeouts, or using the Connector/J connection property 'autoReconnect=true' to avoid this problem.;

SQL []; The last packet successfully received from the server was 661,156 milliseconds ago. The last packet sent successfully to the server was 661,157 milliseconds ago. is longer than the server configured value of 'wait_timeout'. You should consider either expiring and/or testing connection validity before use in your application, increasing the server configured values for client timeouts, or using the Connector/J connection property 'autoReconnect=true' to avoid this problem.;

nested exception is com.mysql.jdbc.exceptions.jdbc4.CommunicationsException: The last packet successfully received from the server was 661,156 milliseconds ago. The last packet sent successfully to the server was 661,157 milliseconds ago. is longer than the server configured value of 'wait_timeout'. You should consider either expiring and/or testing connection validity before use in your application, increasing the server configured values for client timeouts, or using the Connector/J connection property 'autoReconnect=true' to avoid this problem.

第三、加上上面C3P0的配置，注意，由于设置了MySQL的空闲时间是2分钟，因此我们要将配置文件中idleConnectionTestPeriod的value设置为1分钟，即60，不管设置多长，总之要小于MySQL的空闲时间。最后重启程序，再次测试，OK，问题解决了。

大功告成！！！！文字描述得不是很美，程序猿吧，懂的。

总结：解决问题的关键在于找到原因，只要了解其他连接池的配置，相信也能很快解决这个问题。