How do I get my XML button to connect to my file download servlet with a mobile android device?

I apologize if this seems a little rudimentary however I'm at a loss trying to find an example of what I'm trying to do.

I have my file download servlet already set up and it works on my regular web app, however I'm using GWT with that so I know the mobile implementation is going to be different. When a button is selected, it takes the current record parameters and returns with a download screen with the appropriate PDF file.

I'm trying to emulate the same behavior in a mobile version of the same app. I should be able to hit the same servlet, feeding it the same parameters from my web app and trigger the same download. I have the required parameters for the servlet on my mobile device already and I already have my web.xml and my fildownload servlet class setup on my server. Both the client and server are ready to talk, I just do not know how to get them both talking. I have the button created in XML. When OnPress occurs, I want it to send the parameters to the servlet and get the file download back.

I'm new to Android and still learning. I feel like I'm very close. Has anyone done this and if so, could you direct me to an example of it being done or a book/site that goes over this specifically? I really want to learn how to do this.

Any help is appreciated.