definately wasteful. try changing your DBConnection object (which should be called DBConnectionFactory) and maintaining DataSource as a class member. Then in yuor constructor for DBConnectionFactory acquire the datasource from JNDI. Ensure you add a finalize() method to nullify your datasource too for good measure. You could also use the DBConnectionFactory as a singleton by adding a static reference to itself and adding a static method called getInstance but that's another topic
ADC > -----Original Message----- > From: Shapira, Yoav [mailto:[EMAIL PROTECTED] > Sent: 13 September 2004 14:03 > To: Tomcat Users List > Subject: RE: [OFF-TOPIC]Yoav --> RE: Some pretty basic Tomcat > ConnectionPooling Questions???? > > > > Hi, > It's inefficient to do the DataSource lookup (an expensive operation) > every time you need a connection. See Luke's approach in the other > message with a similar subject. > > And please don't put my name in subject lines -- there are a ton of > other people here who can give great advice on this basic design issue > ;) > > Yoav Shapira > Millennium Research Informatics > > > >-----Original Message----- > >From: Caroline Jen [mailto:[EMAIL PROTECTED] > >Sent: Saturday, September 11, 2004 12:43 AM > >To: Tomcat Users List; [EMAIL PROTECTED] > >Subject: RE: [OFF-TOPIC]Yoav --> RE: Some pretty basic Tomcat > >ConnectionPooling Questions???? > > > >This is what I do and would like to have feedbacks: > > > >import java.sql.Connection; > >import java.sql.SQLException; > >import javax.naming.InitialContext; > >import javax.naming.NamingException; > >import javax.sql.DataSource; > > > >public class DBConnection > >{ > > public static Connection getDBConnection() throws > >SQLException > > { > > Connection conn = null; > > > > try > > { > > InitialContext ctx = new InitialContext(); > > DataSource ds = ( DataSource ) ctx.lookup( > >"java:comp/env/jdbc/MySQLDB" ); > > > > try > > { > > conn = ds.getConnection(); > > } > > catch( SQLException e ) > > { > > System.out.println( "Open connection > >failure: " + e.getMessage() ); > > } > > } > > catch( NamingException nEx ) > > { > > nEx.printStackTrace(); > > } > > return conn; > > } > >} > > > >--- "Luke (Terry) Vanderfluit" <[EMAIL PROTECTED]> > >wrote: > > > >> Hi Yoav and all, > >> > >> Thanks for your reply, > >> > >> > But you went a bit too far: the DataSource lookup > >> is potentially > >> > expensive. That you can do in the init() method > >> and keep a reference to > >> > the DataSource, because keeping that reference > >> doesn't use a connection > >> > resource. > >> > Then in your servlet methods, get a connection > >> from the DataSource, use > >> > it, and release it. > >> > In your servlet destroy method, null out your > >> DataSource reference. > >> > So the DataSource lookup is done once, the > >> DataSource reference is kept > >> > as a private non-static member variable of the > >> servlet class, and the > >> > Connenctions are used only within methods, they're > >> not class member > >> > variables. > >> > >> So now I have changed my code to: > >> 1. Declaration of private global variables: > >> <code> > >> private Context ctx = null; > >> private DataSource ds = null; > >> private Connection conn; > >> </code> > >> > >> 2. an init() method: > >> <code> > >> // "init" does DataSource lookup > >> public void init(ServletConfig config) throws > >> ServletException { > >> super.init(config); > >> try { > >> ctx = new InitialContext(); > >> if(ctx == null) { > >> throw new Exception("No Context"); > >> } > >> ds = > >> (DataSource)ctx.lookup("java:comp/env/jdbc/mb"); > >> } // end try block > >> catch(Exception e) { > >> e.printStackTrace(); > >> } > >> } // end init() > >> </code> > >> > >> 3. an openConnection() method: > >> <code> > >> private void openConnection() { > >> try { > >> if(ds != null) { > >> conn = ds.getConnection(); > >> if(conn != null) { > >> message = "Got Connection to DB " + > >> conn.toString(); > >> } > >> } > >> } // end try block > >> catch(Exception e) { > >> e.printStackTrace(); > >> } > >> } //end method openConnection() > >> </code> > >> > >> 4. a destroy() method that nulls the DataSource: > >> <code> > >> public void destroy() { > >> ds = null; > >> } > >> </code> > >> > >> <remarks> > >> -the conn.close() is called in the methods that call > >> openConnection(). > >> -I'm thinking of doing an 'include' for the > >> openConnection method, so I > >> don't have the code for the same method sitting in > >> multiple classes. > >> Would that be a good idea? (maintainability, yes but > >> in terms of > >> overhead?) > >> </remarks> > >> > >> Would this be the 'leanest' scenario for a database > >> connection? > >> thanks again, > >> Luke > >> > >> -- > >> ======================== > >> Luke (Terry) Vanderfluit > >> Mobile: 0421 276 282 > >> ======================== > >> > >> > >> > >--------------------------------------------------------------------- > >> To unsubscribe, e-mail: > >> [EMAIL PROTECTED] > >> For additional commands, e-mail: > >> [EMAIL PROTECTED] > >> > >> > > > > > >__________________________________________________ > >Do You Yahoo!? > >Tired of spam? Yahoo! Mail has the best spam protection around > >http://mail.yahoo.com > > > >--------------------------------------------------------------------- > >To unsubscribe, e-mail: [EMAIL PROTECTED] > >For additional commands, e-mail: [EMAIL PROTECTED] > > > > > This e-mail, including any attachments, is a confidential > business communication, and may contain information that is > confidential, proprietary and/or privileged. This e-mail is > intended only for the individual(s) to whom it is addressed, > and may not be saved, copied, printed, disclosed or used by > anyone else. If you are not the(an) intended recipient, > please immediately delete this e-mail from your computer > system and notify the sender. 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