Mysql报com.mysql.jdbc.exceptions.jdbc4.CommunicationsException: Communications link failure错误

1.尝试登录网站时失败，查看发现出现以下错误：

com.mysql.jdbc.exceptions.jdbc4.CommunicationsException: The last packet successfully received from the server was 259,809,499
 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.

2.根据报错信息可以判断连接池中的连接Connection失效，即超过了有效时间wait_timeout。登录mysql后查看wait_timeout有效时间为28800，即八小时。

show global variables like 'wait_timeout';

3.修改wait_timeout属性，调大数值为31536000（365天，linux最大值为一年）。在my.cnf配置文件中，[mysqlId]下添加wati_timeout、interactive_timeout属性，重启mysql。此时测试发现已经可以连接，基本解决了问题。

(1).编辑my.cnf配置文件

vi /etc/my.cnf

(2).添加wait_timeout属性

[mysqlId]
...
wait_timeout = 31536000
interactive_timeout = 31536000

(3).重启mysql

service mysqld restart

4.为了保证连接池的连接有效，所以修改连接池属性如下：

参考自：http://zeusami.iteye.com/blog/1112827