生成二维码 ``` m('qrcode')->createQrcode($url); ``` 商城二维码 ``` m('qrcode')->createShopQrcode($mid = 0, $posterid = 0); ``` 商品二维码 ``` m('qrcode')->createGoodsQrcode($mid = 0, $goodsid = 0, $posterid = 0); ```