Communications link failure，The last packet successfully received from the server was *** millisecon

failure，The last packet successfully received from the server was *** millisecon"/>

Communications link failure，The last packet successfully received from the server was *** millisecon

使用Connector/J连接MySQL数据库，程序运行较长时间后就会报以下错误：

Communications link failure，The last packet successfully received from the server was * **millisecond ago.
The last packet successfully sent to the server was * **millisecond ago。

其中错误还会提示你修改wait_timeout或是使用Connector/J的autoReconnect属性避免该错误。

后来查了一些资料，才发现遇到这个问题的人还真不少，大部分都是使用连接池方式时才会出现这个问题，短连接应该很难出现这个问题。这个问题的原因：

1. 按照错误的提示，可以在JDBC URL中使用autoReconnect属性，实际测试时使用了autoReconnect=true&failOverReadOnly=false，不过并未起作用，使用的是5.1版本，可能真像网上所说的只对4之前的版本有效。

2. 没办法，只能修改MySQL的参数了，wait_timeout最大为31536000即1年，在myf中加入：

[mysqld]  wait_timeout=31536000  interactive_timeout=31536000  
1

重启生效，需要同时修改这两个参数。

Caused by: com.mysql.jdbc.exceptions.jdbc4.CommunicationsException: Communications link failure  
[09:49:36.821]  
[09:49:36.821]Last packet sent to the server was 0 ms ago.