yes thats what i have in my mind. I have identified that
1) to get a javax.sql.DataSource connection, I need:
1.1) a JNDI name

2) to ge a java.sql.DriverManager connection, I need:
2.1) Driver Name
2.2) Database URL
2.3) Database User Id
2.4) Database Password

Now I can create one class which has 2 methods:
public class ConnectionUtil {
 // used by the app using JBoss
 public Connection getDataSourceConnection( String jndiName ) {...}

 // used by the app not using JBoss
 public Connection getDriverManagerConnection( String driverName, String
databaseUrl, String databaseUserId, String databasePassword) {...}
}

Another option i can think of which is cleaner is to have a Connection
interface:
public interface ConnectionI {
 public Connection getConnection(Properties props);
}

Then 2 seperate classes one for DataSource and one for DriverManager which
implements the interface
public class DataSourceConnection implements ConnectionI {
 private String jndiName;

 // props contains JNDI Name
 public Connection getConnection(Properties props) {...}
}

public class DriverManagerConnection implements ConnectionI {
 private String driverName;
 private String databaseUrl;
 private String databaseUserId;
 private String databasePassword;

 // props contains Driver Name, Database Url, Database User Id, Database
Password
 public Connection getConnection(Properties props) {...}
}

Then a factory:
public class ConnectionFactory {
 public static final int DATASOURCE = 1;
 public static final int DRIVERMANAGER = 2;

 public ConnectionI getConnectionI( int connType, Properties props ) {
   switch(connType)
     case DRIVERMANAGER:
       return new DriverManagerConnection( props );
     case DATASOURCE:
       return new DataSourceConnection( props);
     default:
       return null;
 }
}

So the test code to get a DataSource Connection would be:
Properties props = new Properties();
prop.put("JNDINAME", "MSSQLDS");
ConnectionI connectionI = ConnectionFactory.getConnectionI(1, props);
java.sql.Connection conn = connectionI.getConnection();

And the test code to get a DriverManager Connection would be:
Properties props = new Properties();
prop.put("DRIVERNAME", "sun.jdbc.odbc.JdbcOdbcDriver");
prop.put("DATABASEURL", "jdbc:odbc:database_odbc");
prop.put("DATABASEUSERID", "sa");
prop.put("DATABASEPASSWORD", "password");
ConnectionI connectionI = ConnectionFactory.getConnectionI(2, props);
java.sql.Connection conn = connectionI.getConnection();

What do you think which solution is more gneric and more maintainable?