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
> ========================
>
>
>
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