While not the strict answer to your question, I do have a suggestion.
Don't try to use JDBC on the Android device directly. You'll save a lot of hassle that way. I wrote about that in more detail on the "JDBC vs Web Service for Android" question.
Write your database logic on a web-accessible application server and talk to that application server via HTTP+JSON, SOAP, XML-RPC, or similar. This will be a lot more bandwidth efficient and you can make your app a lot more tolerant of issues with connectivity that way. It also saves you from having to expose your database server directly to the Internet - not much of a worry with PostgreSQL so long as you use SSL, but still better not to have to do at all.
Using JAX-RS on JBoss AS 7, Tomcat 7, or similar you should be able to put together a web RESTful XML/JSON services API for your app pretty easily. People also seem to put REST/JSON APIs together pretty quickly with PHP.
You can write a JSON/REST web API in pretty much any language you like with varying degrees of ease. Just search for REST server yourlanguagename.
"Kaw" has pointed out in a deleted answer that there are also virtual JDBC drivers that tunnel requests over HTTP. These may be suitable for some applications.
