http://www.nabble.com/java.sql.SQLException:-Alrea

http://www.nabble.com/java.sql.SQLException:-Already-closed..strange!-td21195800.html

当偶然出现aleady-closed时,可以尝试在配置连接池时加入
<property name="validationQuery" value="select 1"/>

每次检验是否有空闲的连接.

This causes a very cheap test query to always be run first; if the  
connection has been closed, this gets the failure, and
then a new connection is opened.