Visitors from Shanghai can contact the consulate of Vietnam for obtaining a visa in prior arriving in Vietnam. The process may take around 4 working days.
Vietnam consulate in Shanghai
900 Pudong Da Dao, 3rd Floor Pudong
Tel: 6855 5871
Address: 3F, Huachen Financial Mansion, 900 Pudong Ave, P.C: 200135. (This is on the corner of Pudong Ave and Yuanshen rd. The closest Metro station is Yuanshen Stadium Station on line 6. As this is not a popular line, you may find it easier to take the metro to Century Ave which is also close and an interchange station. If you do go to Yuanshen, the walk is not bad as the street is lined with trees that provide shade.) – This tip is from Joe Kiwi.