I am an American and would like to obtain a visa to china while I am visiting bangkok Thailand.

I was reading through some of the questions and answers responses and I read mix responses regarding if it's possible or not for someone to receive one to china if they currently do not have a thai one in their possession. I will have a couple of weeks to allow for processing and since I am only staying in Thailand for less than 30 days, I am not required to apply for a thai one. Not sure if the Embassy or a travel agent would be possible in obtaining a Chinese one?