Which parameters are needed to build a Alipay post URL ?
Currently using https://openapi.alipaydev.com/gateway.do? as a test URL and service is service=create_forex_trade
I think you need to add following parameters openapi is used for testing purpose while mapi.alipay.net is used for actual transaction purpose
https://openapi.alipaydev.com/gateway.do?_input_charset=utf-8