Adding SDS and boiling works for E. coli and most Gram-negatives, I imagine using straight thermolysis technique on Gram-positive might be difficult. More convention method would provide higher quality genomic DNA. 

It all depends what you are going to do with the template afterwards.

Thanks a lot @Ali Mahmoudpour, Can you please share the detail of using SDS method?  

Thank you @Ali Mahmoudpour for sharing your experience.