What is the point of JavaBeans?

Question

I have put together Web apps without using JavaBeans -- just servlets, JSPs, and regular Java classes. But I keep reading about JavaBeans. All the servlet books seems to emphasize that you should use them, and the new JSTL has a lot built in JavaBean facilities. I'm having a hard time figuring out how and why I should use them. I don't see how they fit in with what I'm doing.
For example, I'm using a connection pool class that could conceivably be turned into a JavaBean. However, this class takes a number of parameters in it's constructor -- driver name, user name, password, database URL, and so on. If it's a JavaBean, it has to have a zero-argument constructor, and that's the constructor that gets called from a JSP when you use <jsp:useBean />. So how would that work? How would it know what database to connect to or what driver to use? Say I declare that it's a JavaBean, give it a dummy zero-argument constructor that I never really call, then instantiate it from a servlet like a regular class, giving it the necessary params. Then it isn't really a JavaBean is it? And I might as well forget the whole bean thing altogether.
That's just one example. I guess one of the main things I don't understand about JavaBeans is: if they have to have a zero-argument constructor, then how can you make use of them in cases where you need a class to be instantiated with specific parameters?
I feel like the only guy on the block who doesn't use JavaBeans. I want to be hip. I would be very grateful for any enlightenment on this subject.
Thank you.
Ethan

Answer 1

I don't think that a Connection Pool class would be an ideal candidate for becoming a JavaBean. One of the most prevalent use of a JavaBean class it to use it as a data object to collect data from your presentation layer (viz. HTML form) and transfer it to your business layer. If the request parameter names match the Bean's property names, a bean can automatically get these values and initialize itself even though it has a zero argument ctor. Then a Bean could call methods in the business layer to do some processing, to persist itself etc.