Re: looking for opinons regarding best practices (jdbc, resultsets, and servlet design)

From:
"javerra" <tnavarra@flipforwardinteractive.com>
Newsgroups:
comp.lang.java.programmer
Date:
7 Feb 2007 07:04:41 -0800
Message-ID:
<1170860681.510774.202180@s48g2000cws.googlegroups.com>
I believe I have been implement an MVC design in the apps I've been
writing. My understanding is that with MVC I would have a "model" of
my data (just a plain javabean), Im using JDBC in a servlet to fill
my bean and do whatever processign logic needs done, this being the
"controller". Im then, stuffing that into a request or session
attribute and sending to a jsp "view". Is my understaning correct? I
guess this still leaves me confused about whether or not I should be
handling my data access form the servlet the way I have been. Thank
you for your thoughts!

On Feb 7, 9:47 am, "dnass" <dnasm...@gmail.com> wrote:

On Feb 7, 2:27 pm, "javerra" <tnava...@flipforwardinteractive.com>
wrote:

Hello all,

Im looking for an opinion regarding best practices. Recently a friend
and I were talking about how we write our code for our web
applications. I tend to keep my jdbc code with my logic in any
servlet I am writing. My friend says that this is bad practice and
that data quries should be broken out into data access objects with
methods that pass back a result set. Is he right? Is this really bad
practice or is it really just a different type of design pattern?
Love to hear everyones thoughts...

Im always doing something like this....

            try {
                Connection Conn = DriverManager.getConnection("jdbc:mysql://
sql.useractive.com/USERNAME?user=USERNAME&password=PASSWORD");

                // Do something with the Connection
                Statement Stmt = Conn.createStatement();
                ResultSet RS = Stmt.executeQuery("SELECT * from SOMETABLE");

                while (RS.next()) {
                    out.println(RS.getString(1));
                }
                // Clean up
                RS.close();
                Stmt.close();
                Conn.close();

            }
            catch (SQLException E) {

}


Hello Javera,

You should have a look at MVC model.

And for the code you've written I would have wrote it this way :
Connection Conn = null;
Statement Stmt = null;
ResultSet RS = null;
        try {
                Conn =
DriverManager.getConnection("jdbc:mysql://
sql.useractive.com/USERNAME?user=USERNAME&password=PASSWORD");

                // Do something with the Connection
                Stmt = Conn.createStatement();
                RS = Stmt.executeQuery("SELECT * from SOMETABLE");

                while (RS.next()) {
                    out.println(RS.getString(1));
                }

            }
            catch (SQLException E) {
                 // handle the exception
            }
            finally{
                // Clean up
               try{
                  RS.close();
               }
               catch(Exception ex){}
               RS = null;
               try{
                  RS.close();
               }
               catch(Exception ex){}
               RS = null;
               try{
                Conn.close();
               }
               catch(Exception ex){}
              Conn= null;

            }
because if you have an exception while executing the query
with your source code you'll never close your connection.

I hope this helps
DNass

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