Do they serve alcoholic beverages in Bandung? Can I get it from 7-11
From 7-11, no. Minimarts do not have alcohol licence.
Big supermarkets can sell beer. Only specially licenced shops can sell vodka, gin etc.
Buying strong spirits during Ramadan may be impossible in general. Beer is available, no problem.
Aside from purchasing alcohol in supermarkets, there are also several bars at the top end of Jalan Braga.
you are most welcome and happy travels!