Default Implementation For an Interface

[Kevin]

I was implementing a framework and I found that I wanted two things.
  - A strong set of interfaces so that I can get what I want from a 
variety of sources.
  - Some basic implementations of these interfaces.

For example, say I was writing a database class.  I could either name 
the interface Database and call the class DatabaseImplementation or 
something but that is ugly.  If I call the interface IDatabase, the 
Database class looks nice but I need to convince users to write 
functions that take IDatabases not Databases.

I was wondering if there was any way to implement a default 
implementation.  This way, I could create my Database interface and 
classes could implement that but if you called `new Database()` you 
would still get a basic database.

I thought about doing it in different modules but it just gets messier 
as you have to fully qualify all of the names so both look ugly.  I 
though about overloading the new operator for the interface but it would 
have to be final and that would mess everything up.  I though about a 
meathod like `Database.newDefault()` but that is messy and has no 
meaning in a derived class.

I couldn't find anything about this so I was wondering what you would 
recommend.  Should I just pick a naming scheme?