Can I apply a Visa to Guangzhou even I am still here in Japan through a representativre ?

I am planning to attend a Trade Fair in Guangzhou by April coming from Manila. Can I apply a Visa in advance through a representative and just have my Visa stamp to my Passport when I come to Philippines by April. And please may I know the documents needed for applying the said Visa. My Friend from Malta was the one inviting me and he will be the one to pay my plane ticket and Hotel accomodations in Guangzhou China. We will be meeting there in Guanzhou for the Fair. I just want to apply for a 7 days Tourist Visa. How many weeks before April should I apply. I am planning to come to Philppines on April 11 and go to Guanzhou on April 15 - April 22, 2013.