Rain Versus Sun during my traveling

I'm considering joining a tour to China for 2 weeks late July and early August. Itinerary is Beijing area July 22-28, Xian July 28-30, Shanghai area July 30-31 and Hong Kong area August 1-4.
My question is regarding weather: I LOVE sun and heat on my summer trips; I don't like rain and clouds. I have no problem with brief thunderstorms, don't mind getting soaked - but I do NOT want to go somewhere where there may be multiple overcast days with little sunshine.
All reports say China gets most rain July and August - but what kind of rain? Enough to ruin trip? Could it rain for a week straight? Do you think I'll get a decent amount of sunshine?
Thank you thank you for any replies! Appreciate any detail! Never been anywhere near the Far East before!