public static void main(String[] args) {
// this program needs a persistence framework
// at runtime an implementor is chosen between file system
// implementation and
// database implememtor , depending on existence of databse drivers
PersistenceImplementor implementor = null;
if (databaseDriverExists()) {
implementor = new DabatasePersistenceImplementor();
} else {
implementor = new FileSystemPersistenceImplementor();
}
Persistence persistenceAPI = new PersistenceImp(implementor);
Object o = persistenceAPI.findById("12343755");
// do changes to the object
// then persist
persistenceAPI.persist(o);
// can also change implementor
persistenceAPI = new PersistenceImp(new DabatasePersistenceImplementor());
persistenceAPI.deleteById("2323");
}
