[OSM-dev] java osm renderer

[BG]

Hej.

I want to try to make a renderer with java. But i do not know how i get 
the geometry information and interpret it.
I think it would be easy to make sql requests about the objects to get. 
But the geometry column (which comes with postgis) confuses me, this is 
a bunch of numbers.
Are there already some solutions in java? Does it make sense to use 
postgis or would it be easier to use the mapfile?

thanks and best regards