Android SD Card Function to read SD Card/check for a Dir/File and give back the Path

I need a Function (snippet Code) what does the follow... I need to add a Dir and Map in a Directory from a SD Card by Hand. My App need to read the MApdata from SD Card. The Way i will go - because Android KITKAT doesnt allow to write on a SD Card. I need for now a Patch what do the follow. A User write a new Dir on a SD Card and put a Map in this Directory. Also the User delete the Original Map on Main Device. The Main Device know by start the Software - that the Map is not longer there and ask me to load again from Server or search on SD Card? Now the Patch i need, will activate and search for a SD Card (any SD Card in a Device and must work on all android Devices) - It will search for a hardcoded Dir (by example = maps/[login to view URL]) on the SD Card. If there more then one Place to search, the patch should seek all given Sd Cards. If found, it should look for the hardcoded Memory and give me a correct path for the file back. Thats it - if there any what can build this? Exactly like i want and 99,9 % working with each Android Device? (This is a must, because, if this only working in some Devices, then is useless for me) Or if any what allready have done this and can sell me this snippet ? Let me know, kasi