[{"code":"PARAM_ERROR","detail":{"location":"body","value":""},"message":"输入源“/body/sub_mchid”映射到字段“子商户号/二级商户号”必填性规则校验失败，此字段为必填项"}] 我是普通商户，官方sdk 要求必写 // 构建service AppServiceExtension service = new AppServiceExtension.Builder().config(Config****).build(); // request.setXxx(val)设置所需参数，具体参数可见Request定义 // 跟之前下单示例一样，填充预下单参数 PrepayRequest request = new PrepayRequest(); Amount amount = new Amount(); amount.setTotal(10); request.setAmount(amount); request.setDescription("测试商品标题"); request.setSpAppid(**); request.setSpMchid(**); request.setNotifyUrl("https://notify_url"); request.setOutTradeNo("out_trade_no_0010000"); // 调用下单方法，得到应答 // response包含了调起支付所需的所有参数，可直接用于前端调起支付 PrepayWithRequestPaymentResponse response = service.prepayWithRequestPayment(request,**);