报错信息：

1，The last packet successfully received from the server was 59,002 milliseconds ago. 
	 The last packet sent successfully to the server was 1 milliseconds ago.
2，Caused by: java.io.EOFException: Can not read response from server. Expected to read 4 bytes,
	 read 0 bytes before connection was unexpectedly lost.	
3，ERROR [com.alibaba.druid.pool.DruidDataSource] - discard connection com.mysql.jdbc.exceptions.jdbc4.CommunicationsException: Communications link failure

数据库连接池配置：

	<bean id="emp_dataSource" class="com.alibaba.druid.pool.DruidDataSource" init-method="init" destroy-method="close">
		<property name="url" value="jdbc:mysql://192.168.2.111:3306/test?useUnicode=true&amp;characterEncoding=UTF-8&autoReconnect=true" />
		<property name="username" value="root" />
		<property name="password" value="root" />
		<property name="initialSize" value="1" />
		<property name="minIdle" value="1" />
		<property name="maxActive" value="20" />
		<property name="maxWait" value="60000" />
		<property name="timeBetweenEvictionRunsMillis" value="60000" />
		<property name="minEvictableIdleTimeMillis" value="300000" />
		<property name="testWhileIdle" value="true" />
		<property name="testOnBorrow" value="true" />
		<property name="testOnReturn" value="false" />
		<property name="poolPreparedStatements" value="true" />
		<property name="maxPoolPreparedStatementPerConnectionSize"
			value="20" />
	</bean>

报错原因：

mysql 连接闲置一定时间后，mysql数据库就会自动断开连接，spring 的 jdcp 连接池中的connection是无效的，导致报错（使用数据库连接工具同样也会报错）

解决方法：

修改连接等待时间，默认是28800，8小时，

1，不重启mysql数据库：

SET GLOBAL interactive_timeout = 31536000;
FLUSH PRIVILEGES;

SET GLOBAL wait_timeout = 31536000;
FLUSH PRIVILEGES;

2，修改配置文件my.cnf，添加下面两个参数，重启mysql数据库：

[mysqld]
interactive_timeout = 31536000
wait_timeout = 31536000