Hello Gabriel,
You wont find a one stop shop guide to implementing SSL in the ABAP+JAVA world but a collection of docs that will help you do it.
Setting up SSL on JAVA or ABAP is a fairly painless task and there are plenty of guides that will help you with that. eg: (just a small sample)
How to configure SSL by using configuration tool in SAP NetWeaver Administration 7.3
SSL Configuration in SAP ABAP AS and JAVA AS – Step-by-step procedure
Just take into account that depending on the version of your systems some steps will be different.
Also bear in mind that your question poses a lot of questions.
eg:
If a user connects to the HTTP port, I assume you'd want the request automatically redirected to the HTTPS port.
Do you use virtual addresses ? eg: http://myportal.mycompany.com ?
Do you use software or hardware based load balancers (bluecoat, netscaler, SAP WD) ?
Do you use reverse proxies ?
Your connections are only in intranet or from internet also ?
You see what I'm getting at in terms of questions .......
I hope my little contribution above helps gives you some guidance.
Kindest Regards,
Amerjit