China Reaches Record Trade Surplus, Raising Alarm Abroad

The NYTimes article talks about the growing China's trade surplus that reached 100B in June.

Yet it does not discuss the exchange rate implications of the trade imbalance. How does China manage to keep the exchange rate with USD relativelly stable in face of the large trade imbalance? Taking the exchange rate situation into account, should we be worried about China's actions, or should we rather be thankful and acknowledge a symbiotic relation with China that benefits both China and the US/EU.