We were in Beijing July 2006 for six nights and I was actually surprised by the number of Chinese men wearing shorts. We stayed at the Hilton off the third ring road. I recall walking down the street to the Lufthansa Center (which had a nice market in the basement) and being surprised by the number of men in shorts. The vast majority had long pants, but more than a few in shorts. It was fairly warm, so maybe that accounts for it?

Didn't notice the same in Shanghai, but then I was there in December.