Re: Database helper class with PreparedStatements

From:
=?ISO-8859-1?Q?Arne_Vajh=F8j?= <arne@vajhoej.dk>
Newsgroups:
comp.lang.java.programmer
Date:
Thu, 08 Nov 2007 19:38:45 -0500
Message-ID:
<4733ac16$0$90275$14726298@news.sunsite.dk>
teser3@hotmail.com wrote:

I have a JDBC working with Oracle 9i where database is inserted/
updated maybe 10 times at most during a week with very little usage in
my Tomcat 4.1.3 Container.

The Database classes I have used for the past year are working great
but I wonder if I should be closing my connection in my database
helper class with Prepared statements:

public class DbInsert
{
    private PreparedStatement stat;
    private Connection connection;

    public DbInsert(Connection connection)
    {
         this.connection = connection;
    }

    public void cityInserter(FormBean city) throws SQLException
    {
        stat = connection.prepareStatement("Insert into City (street,
school) values (?,?)");
        stat.setString(1, city.getStreet());
        stat.setString(2, city.getSchool());
       stat.executeUpdate();
    }

    //more Methods with preparedstatements here....
}

....

public class DbWork
{

    private Connection connection = new
ConnectionMgr().getConnection();

   public dbMethod(FormBean city)
   {
        try
       {
               new DbInsert(connection).cityInserter(city);
       }
       catch(SQLException ex)
       {
              System.out.println(ex);
       }
       finally
       {
             connection.close();
       }
   }

   //more db methods using prepared statements here

.....
}

When I experiment and put a close statement in the [b]DbInsert[/b]
class method then my database insert wont work because it would be
closed when it is called in the [b]DbWork[/b] class?


I am surprised that it even work with a connection.close in dbMethod.

For very small single desktop apps you can consider a single
permanent open database connection.

For a complex app or any web app, then you should use a connection
pool and only keep the connection open when you need it.

Something like:

      public void cityInserter(FormBean city) throws SQLException
      {
          Connection connection = new ConnectionMgr().getConnection();
          PreparedStatement stat = connection.prepareStatement("Insert
into City (street, school) values (?,?)");
          stat.setString(1, city.getStreet());
          stat.setString(2, city.getSchool());
          stat.executeUpdate();
          connection.close();
      }

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