Okay, thank you very much.
Now I started with apache dbcp, but I don't understand completely.
I have a singleton class wich gets properties from a property file and uses them to open connections and store them in the connectionpool.
Like this (snipped code)
Then I have this method "checkout" wich should give a connection to the user, this is being called whenever a user loads a page.
But with my previous way of connecting, I closed the connection everytime the requested page was done loading.
I used a method "checkIn()", I don't understand how i could return the method in the connection pool...