这里就不详细介绍了，请参考之前写的一篇文章 支付宝支付-扫码支付详解

如有疑问请发issues或者在博客中留言

IJPay 接口

    /**
     * 统一收单线下交易预创建
     * 扫码支付
     * @param model
     * @param notifyUrl
     * @return {String}
     * @throws {AlipayApiException}
     */
    public static String tradePrecreatePay(AlipayTradePrecreateModel model, String notifyUrl) throws AlipayApiException{
        AlipayTradePrecreateResponse response = tradePrecreatePayToResponse(model,notifyUrl);
        return response.getBody();
    }
    /**
     * 扫码支付
     * @param model
     * @param notifyUrl
     * @return {AlipayTradePrecreateResponse}
     * @throws {AlipayApiException}
     */
    public static AlipayTradePrecreateResponse tradePrecreatePayToResponse(AlipayTradePrecreateModel model, String notifyUrl) throws AlipayApiException{
        AlipayTradePrecreateRequest request = new AlipayTradePrecreateRequest();
        request.setBizModel(model);
        request.setNotifyUrl(notifyUrl);
        return AliPayApiConfigKit.getAliPayApiConfig().getAlipayClient().execute(request);
    }

代码示例

https://github.com/Javen205/IJPay-Demo

    /**
     * 扫码支付
     */
    @RequestMapping(value ="/tradePrecreatePay")
    @ResponseBody
    public String tradePrecreatePay() {
        String subject = "Javen 支付宝扫码支付测试";
        String totalAmount = "86";
        String storeId = "123";
        String notifyUrl = aliPayBean.getDomain() + "/alipay/notify_url";

        AlipayTradePrecreateModel model = new AlipayTradePrecreateModel();
        model.setSubject(subject);
        model.setTotalAmount(totalAmount);
        model.setStoreId(storeId);
        model.setTimeoutExpress("5m");
        model.setOutTradeNo(StringUtils.getOutTradeNo());
        try {
            String resultStr = AliPayApi.tradePrecreatePay(model, notifyUrl);
            JSONObject jsonObject = JSONObject.parseObject(resultStr);
            return jsonObject.getJSONObject("alipay_trade_precreate_response").getString("qr_code");
        } catch (Exception e) {
            e.printStackTrace();
        }
        return null;
    }