How to make a soap client in Java?

I have gone through many answers on stack overflow on how to make a soap client in Java but i still can't wrap my head around it.

Requirements

1) I have been using loadrunner for making Soap requests but I am gonna discontinue the product and wanted to make a simple Java soap client.

2) I need to automate the soap client to test the web service every day and generate logs. There are gonna be 20-25 soap web services to be tested at a time. How can I achieve it?

3) I have gone through SAAJ and JAX-WS but I found them too complicated and to also couldn't figure out how can I head custom HTTP headers in the requests.

It seems like I am designing Loadrunner again. So my question is what can be the steps to achieve the above requirements.

I have a wsdl file, certificate, URL and some custom HTTP headers to be included in the request.

Also, should I use SOAPUI to generate the request xml first, would that be a better idea?