Hey, I'm going to China on May, 2010. Previously, I will be travelling through Southeast Asia for three months so I cannot arrange my Visa to China in my country, because by the date i will be crossing to China my visa may have became invalid.
Is it possible to apply for a Visa of more than 3 months of validity? in case it's not, is it possible to arrange my visa for china in Vietnam for example?

Thanks in advance for your help