Re: Database helper class with PreparedStatements

From:

Lew <lew@lewscanon.com>

Newsgroups:

comp.lang.java.programmer

Date:

Mon, 12 Nov 2007 09:24:23 -0500

Message-ID:

<aqydnTsBat2K_6XanZ2dnUVZ_gednZ2d@comcast.com>

Are Nybakk wrote:

Arne VajhQj wrote:

Are Nybakk wrote:

I started replying to this post, but I gave it up. I don't quite get
what you want answered here. I'll give you some tips on how to
organize things.

Make a class that takes care of the database connection:

public class DatabaseConnector {

   private Connection con;

   public DatabaseConnector(user, pass, ...) {
      con = ...;
   }

   public Connection getConnection() {
      return con;
   }

   public void close() {
      con.close();
   }

   //...

}

What does that class provide that Connection does not ?

I see your point. The idea is to isolate what has got to do with the
actual initialization and maintainance of the server connection. Only
this class needs to know about JDBC driver and such. That way it can
also be reused.

And a database handler class:

public class DatabaseHandler {

   private DatabaseConnector dbCon;
   private Connection con;
   private PreparedStatement stmt1 = new PreparedStatement("...");

   public DatabaseHandler(user, pass, ...) {
      dbCon = new DatabaseConnector(user, pass, ...);
      con = dbCon.getConnection();
   }

   public void insertSomeObject(SomeObject obj) {
      stmt.setXxx(...);
      //...

      stmt.executeXxx();
   }

   /...

   public void closeConnection() {
      dbCon.close();
   }

}

That DatabaseConnector is not needed is emphasized by the fact
that you have both the DatabaseConnector wrapper and the underlying
Connection as fields here.

Alright let me revise. I guess I wrote this in a hurry.

(Error catching left out)

public class DatabaseConnector {

private String serverURL = "...";

If you're going to hard-code these values, make them static final Strings (and
therefore use all upper case in their names).

   private String driverName = "...";
   private Connection con;
   private PreparedStatement stmt1 = new PreparedStatement("...");
   //...

   public DatabaseConnector(user, pass) {
      Class.forName(driverName);
      con = DriverManager.getConnection(serverURL, user, pass);
   }

You don't need to load the driver class but once, not every time you make an
object. You could do it in a static initializer for the class (assuming you
followed my advice to make the driver name a static variable, too).

--
Lew