Dynamically loading and registering JDBC driver from an archive (zip - jar)

Question

I'm programming an JDBC driver tester.
I have to load dynamically any driver from an archive (jar or zip) after the user uploaded it.
I think i did it well with my ClassLoader, i can get an instance of the driver and use any method like (getMinorVersion()) but when i registering it fail.
There is no error but the driver is not registered.
I rode the DriverManager log (with his logwriter) and he says :
skipping: driver[className=oracle.jdbc.driver.OracleDriver,oracle.jdbc.driver.OracleDriver@5439fe]
skipping: driver[className=oracle.jdbc.driver.OracleDriver,oracle.jdbc.driver.OracleDriver@2b7db1]
(two times, it looks curious isn't it ?)
This is a part of my code :
Driver pilote = (Driver)Class.forName(driverClass.getName(), true,this).newInstance();
System.out.println("Minor Version = "+ pilote.getMinorVersion());
PrintWriter printwriter = new PrintWriter(new OutputStreamWriter(System.out));
DriverManager.setLogWriter(printwriter);
DriverManager.registerDriver(pilote);
System.out.println("Driver registered\n");

Answer 1

I have made a simple test :
public static void main(String[] param)
System.out.println("Loading Driver from JAR ...");
try
File jar = new File("c://mbm//drivers//oracle.jar");
URL aurl[] = {jar.toURL()};
URLClassLoader urlclassloader = new URLClassLoader(aurl, ClassLoader.getSystemClassLoader());
Class.forName("oracle.jdbc.driver.OracleDriver", true, urlclassloader);
PrintWriter printwriter = new PrintWriter(new OutputStreamWriter(System.out));
DriverManager.setLogWriter(printwriter);
Enumeration listDriver = DriverManager.getDrivers();
System.out.println("[---------Drivers-----------]");
while (listDriver.hasMoreElements())
Driver driver = (Driver) listDriver.nextElement();
System.out.println("->> "+driver.getClass().getName());
catch (MalformedURLException e)
e.printStackTrace();
catch (ClassNotFoundException e)
e.printStackTrace();
This displays that :
Loading Driver from JAR ...
skipping: driver[className=oracle.jdbc.driver.OracleDriver,oracle.jdbc.driver.OracleDriver@9ec21d67]
[---------Drivers-----------]
D:\www\tomcat\webapps\mbm\WEB-INF\classes>
I think there is in this case only one instance