1.小程序可以通过静默授权（wx.login）拿到openid

2.小程序可以通过确认授权（wx.getUserInfo）拿到openid+uuid

openid、uuid是对当前小程序的生成惟一用呢标识

详见链接

https://developers.weixin.qq.com/miniprogram/dev/framework/open-ability/login.html

https://developers.weixin.qq.com/miniprogram/dev/api/open-api/login/wx.login.html

https://developers.weixin.qq.com/miniprogram/dev/api/open-api/user-info/wx.getUserInfo.html