Regarding voltage you should be safe in China. And most hotels have adapters.

Regarding your flight I'd say NO (http://www.chinaeastern.co.uk/planes.html - they mention 'laptop power ports' in first and business, no mention in economy).

As you can see at http://www.seatguru.com/charts/intl_economy.php, power ports in economy are still quite rare.

I once had luck asking a C/A on a CZ flight to charge my laptop. You could try that too.

/ Nielsen