plotting - Obtain data points from a density plot

I have a density plot, for example

DensityPlot[Sin[x*y],{x,0,2pi},{y,0,2pi}].

Then I would like to collect points from this densityplot into a file so that I can always use ListDensityPlot to draw these points again, or I may draw these points by some other software.

I read several posts on how to do that for Plot, but how can I generalize them to DensityPlot?