I do this sort of research on a regular basis for award tickets, albeit to much more obscure places than Shanghai (as such, skip the rest of this paragraph if you only care about SH). Step 1: google "<CITY NAME> airport wiki" in order to figure out what airlines fly there and from which cities. Step 2: after verifying that airline X is member of desired alliance, go to its website and check schedules (often 3-4 flights per week). Step 3: figure out easiest way to get from where I am to the city I chose in step 2.

As for MCO-China, both AA and UA fly MCO-ORD-PEK/PVG.

Also,

UA- MCO-SFO-PEK/PVG
CO -MCO-EWR-PEK/PVG
DL- MCO-DTW-PVG