How to create Helper class?

Question

The code I am working on right now is related to get a Connection and it needs to support with and without app server.
For that purpose I have an interface
public interface ConnectionManager {
  public Connection getConnection() throws CannotGetConnectionException;
  public void closeConnection( Connection connection ) throws CannotCloseConnectionException;
}Then I have a "DriverManager" and a "DataSource" implementation of it:
public class DriverManagerConnectionManager implements ConnectionManager {...}
public class DatasourceConnectionManager implements ConnectionManager {...}Then I have a Factory class to give ConnectionManager
public final class ConnectionManagerFactory {
  public static final int DRIVERMANAGER = 1;
  public static final int DATASOURCE = 2;
  public static ConnectionManager getConnectionManager( int connectionManagerType ) {
    ConnectionManager connectionManager = null;
    switch ( connectionManagerType ) {
      case DRIVERMANAGER:
        connectionManager = new DriverManagerConnectionManager();
        break;
      case DATASOURCE:
        connectionManager = new DatasourceConnectionManager();
        break;
      default:
        connectionManager = null;
    return connectionManager;
  }So the steps for a unit-of-work (which are defined in Stateless Session Beans) are :
1) get ConnectionManager from ConnectionManagerFactory (the standalone web application will use DriverManager; others will use DataSource)
2) get Connection from ConnectionManager
3) complete your work with that Connection
4) close that Connection through ConnectionManager
I have tested it and it is working good. Now I am thinking that above Steps 1), 2) and 4) are common for all units-of-work. Right now I am repeating them in each of Stateless Session Beans. Is there any better way to handle it ? What is a purpose of Helper class?
Thanks

Answer 1

(damn it... finish a thought....)
Anyway, the point is you still have to get the
ConnectionManager, call getConnection and call
closeConnection in your class. You can't encapsulate
everything into 1 method call all the time.what if i create a class :
public class ConnectionHelper {
  ConnectionManager connectionManager = null;
  public static Connection getConnection(int connectionManagerType) throws CannotGetConnectionException {
    connectionManager = ConnectionManagerFactory.getConnectionManager( connectionManagerType);
    if (connectionManager == null)
      throw new CannotGetConnectionException("Failed to establish Connection Manager");
    else
      return connectionManager.getConnection();
  public static void closeConnection() throws CannotCloseConnectionException {
    if (connectionManager == null)
      throw new CannotCloseConnectionException("Connection Manager is not established");
    else
      connectionManager.closeConnection();
}Then in my SSB code for example :
ConnectionHelper ch = new ConnectionHelper();
boolean getConnection = false;
try {
  ch.getConnection();
  getConnection = true;
} catch(CannotGetConnectionException cgce){
} finally {
  if (getConnection) {
    try {
      ch.closeConnection();
    } catch(CannotCloseConnectionException ccce) {
}Does it make sense?