It depends, in many cafes and pubs in Germany they will not bother as long as you don't block a place in a crowded place without consuming some beverage or food.
In many places you will find free WiFi or payd hotspots from the Telekom or another provider in the vicinity.
Be aware, that there is the rule, that the cheaper a hotel is, the better is the chance to get free internet access.
A good way to connect is to get an O2 mobile account. You can get it with a one Month termination term and at least in all greater cities the access is more than ok (HDSPA+). (Use the phone as WiFi-Router).