I found a train ticket office at the MagLev Long Yang Station. That means, you can directly buy train ticket from Shanghai Railway Station to any train destinations. Here are the instructions:
1. Get out of the Maglev Station to the ground floor.
2. Turn north (if you still can tell directions) and enter the building of Metro Line #2 Long Yang Rd. Station.
3. Go straightly ahead till to go through the building and reach the Long Yang Rd.
4. Turn back and you will see an outlet of the train ticket office on the first floor of the building.
I believe this piece of information is very helpful to visitors who want to transit to train after leaving Pudong Airport by Maglev.