connection pooling with servlets

I am a novice, but thought it would make more sense to post this here. I'm trying to write a basic webstore app for a school project and I'm having trouble getting more than one servlet to access the database connection. I tried the method described on the PostgreSQL site - as I understood it. That entailed opening a connection in one servlet and then having code like this in other servlets that need connections:

Connection grabConnection(HttpSession userSession){
ds = (Jdbc3PoolingDataSource) userSession.getAttribute("dSource");
Connection con = null;

try {
con = ds.getConnection();
// use connection
} catch(SQLException e) {
// log error
} finally {
if(con != null) {
try {con.close();}catch(SQLException e) {}
}
}
return con;
}

The trouble is (I'm sure you see it already) that passing a dataSource object in a session doesn't seem to work. If I don't have a dataSource, then I can't make a connection and if I try to create a new connection, I get the error that is something like "Connection with that name already exists". Any help and I'd be gratefull. Thanks.

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