为什么每次重新部署时都需要刷新连接池?

I have successfully made a connection to a remote MySQL server through Glassfish, however each time I make a change to the code or XHTML files, I need to open the administrator panel of Glassfish and flush the connection pool, otherwise I get the following error when I just refresh the page. Has anybody experienced this? I can post code or other information if it is needed. I have successfully made a connection to a remo