visa exemption of 48 hours for visiting shangai for french

I am frecn, and would like to go on holiday to shangai, to stay only, 2 days+48 hours. If i buy a return ticket from london to shangai, for a stay in shangai, of 48 hours, is it ok? do i need a visa, do i still need an onward ticket, i just want to go to shangai, for 2 days, holidays, can u answer me?