tomcat连接池,重复多次调用方法出错： Connection is closed
http://topic.csdn.net/u/20090206/23/fcb94d20-c996-4e00-9951-966a509c849d.html
并发时出现的 java.sql.SQLException: 关闭的 Resultset: next
http://topic.csdn.net/u/20100815/16/ecca6662-feb6-4942-8495-6dd67260dc22.html
关于连接池的问题
http://topic.csdn.net/u/20081216/22/ff2d17d9-0722-4c0e-8656-7e8aa3e2ccb2.html