Is it possible to hail a taxi in Shanghai on the street at 5 a.m.?

Hello. I have an early flight on 31st of January and I need to get to the Pudong airport around 6 o'clock in the morning. Could you tell me how long does it take a cab to get from Guilin Lu(Guilin Park) in Xuhui to Pudong airport? And is it possible to hail a cab on the street at 5 a.m. or I have to book it in advance?
Many thanks.