How can I get a smart card for city buses, subways ,etc. for Beijing and Shanghai?

Hey, firstly, you have to buy the smart card in each city for their use. In BJ, you can get it at most MTR station, public bus hubs, or some banks.

In Shanghai, you can buy that at local main Railway Station and South Railway Station MTR Stations, Pudong Developement Bank (hongqiao airport branch) and the ticketing office of Maglev at PVG.

I seem to see some relevant map at BJ and Shanghai pages on this website. You can try find.