How can I have multiple SSL certificates for a Java server

I have an in-house HTTP server written in Java; full source code at my disposal. The HTTP server can configure any number of web sites, each of which will have a separate listen socket created with:

skt=SSLServerSocketFactory.getDefault().createServerSocket(prt,bcklog,adr);

Using a standard key store created with the Java keytool, I cannot for the life of me work out how to get different certificates associated with different listen sockets so that each configured web site has it's own certificate.

I'm in a time pinch for this now, so some code samples that illustrate would be most appreciated. But as much I would appreciate any good overview on how JSSE hangs together in this regard (I have searched Sun's JSSE doco until my brain hurts (literally; though it might be as much caffeine withdrawal)).

Edit

Is there no simple way to use the alias to associate the server certificates in a key store with the listen sockets? So that:

• The customer has one key store to manage for all certificates, and
• There is no need to fiddle around with multiple key stores, etc.

I was getting the impression (earlier this afternoon) that I could write a simple KeyManager, with only chooseServerAlias(...) returning non-null, that being the name of the alias I wanted - anyone have any thoughts on that line of reasoning?

Solution

The solution I used, built from slyvarking's answer was to create a temporary key store and populate it with the desired key/cert extracted from the singular external key store. Code follows for any who are interested (svrctfals is my "server certificate alias" value):

    SSLServerSocketFactory              ssf;                                    // server socket factory
    SSLServerSocket                     skt;