Uusing Beans to hold Database connection objects

Question

Hi,
I am kind of new to Java. I wanted to create a db connection object and use the same in the rest of the pages within the session.
In the first page I got the connection object and along with other values I created a bean with scope session and stored the connection object using the setProperty method.
In the next page I retrieve the values using the getProperty method and pass the connection object to a method which updates the database.
When I execute this I get a Runtime error pointing to the method invoked. When I execute the method in standlone mode calling from main method it executes fine.
Can anyone tell me if there is a problem when storing and retrieving objects using the setProperty and getProperty methods.
Regards
VM

Answer 1

For application listeners, see http://www.onjava.com/pub/a/onjava/2001/04/12/listeners.html and also JavaDocs at sun.( ServletContextListener class is in javax.servlet package )
You should do the initialization and putting the instance in application scope in public void contextInitialized(...) method of your listener, by for example block of code like,
public void contextInitialized( ServletContextEvent sce ) {
     // Gettin' your servlet context object for current web application
     ServletContext application = sce.getServletContext();
     // instanciate your DB bean
     MyDataPool db = MyDataPool.getInstance();
     // puttin' instance in scope for later use
     application.setAttribute( "db", db );
This causes you when needed, use ServletContext's getAttribute( "db" ) method to retrieve your database.
for now you just need to add to your "web.xml" <listener> element for your listener class.
<listener>
     <listener-class>mypackage.MyServletContextListener</listener-class>
</listener>
i hope these helps ;)