how to get columns parameters from request object as array at server side(action class)?

nishu

I am trying to get request object's param directly in an array.
param structure:
columns[0][search][value]......etc
and explain me about this param?.i mean is it an json like that.
i tried like this in my action class,
String columns[]=request.getParametersValues("columns");
but this returns null.
Help me out!! and how to give line break here in this forum?
Thanks!