微信小程序登录会话密钥session失效解决方案

# app.js中：
//app.js
App({
  /*
    当小程序初始话完成，会触发onlaunch(全局只触发一次)
  */
  onLaunch: function () {
    // 登录
    this.my_login()
  },
  my_login:function(){
    let that = this
    wx.login({
      success: res => {
        // 发送 res.code 到后台换取 openId, sessionKey, unionId
        console.log(res.code)
        wx.request({
          url: that.globalData.baseurl + "login/",
          data: { "code": res.code },
          method: "POST",
          success(e) {
            wx.setStorageSync('token', e.data.data.token)
          }
        })
      }
    })
  },
  globalData: {
    userInfo: null,
    baseurl:"http://127.0.0.1:8000/"
  }
})
# 页面js中：
// 先拿到app全局对象
const app = getApp()
user1:function (e) {
    wx.getSetting({
      success(res) {
        if (res.authSetting['scope.userInfo']) {
          wx.getUserInfo({
            success: (res) => {
              console.log("res",res) //这个res就是用户的信息
              // 将数据发送后端
              wx.request({
                // 发送iv,encryptedData
                url: app.globalData.baseurl + "getinfo/",
                data:{
                  iv:res.iv,
                  encryptedData: res.encryptedData,
                  token:wx.getStorageSync("token")
                },
                method:"POST",
                success:(e) =>{
                  console.log('后台返回的数据',e)
                }
              })
            },
          })
          // 判断是否过期
          wx.checkSession({
            success() {
              //session_key 未过期，并且在本生命周期一直有效
            },
            fail() {
              // session_key 已经失效，需要重新执行登录流程
              app.my_login() // 重新登录，更新session_key
              wx.getUserInfo({
                success: (res) => {
                  console.log("res啦啦啦", res) //这个res就是用户的信息
                  // 将数据发送后端
                  wx.request({
                    // 发送iv,encryptedData
                    url: 'url',
                  })
                },
              })
            }
          })
        }
      }
    })
  }

# 登录：略
# urls.py
path('getinfo/', user.Info.as_view()),
# user.py
from django.core.cache import cache
from api.models import Wxuser
from api.wx import WXBizDataCrypt
from api.my_ser import wx_user_ser
from rest_framework.response import Response
class Info(APIView):
    def post(self, request):
        param = request.data
        if param['iv'] and param.get("token") and param.get("encryptedData"):
            iv = param['iv']
            encryptedData = param.get("encryptedData")
            session_key_openid = cache.get(param.get("token"))
            if session_key_openid:
                sessionKey, openid = session_key_openid.split("&")
                # 解密
                user_info = WXBizDataCrypt.WXBizDataCrypt.get_info(sessionKey, encryptedData, iv)
                print('user_info', user_info)
                save_data = {
                    "name": user_info['nickName'],
                    "avatar": user_info['avatarUrl'],
                    "language": user_info['language'],
                    "province": user_info['province'],
                    "city": user_info['city'],
                    "country": user_info['country'],
                }
                # 把用户信息存入数据库
                Wxuser.objects.filter(openid=openid).update(**save_data)
                # 测试：把童虎信息返回给前台
                user = Wxuser.objects.filter(openid=openid).first()
                user = wx_user_ser(instance=user, many=False).data
                return Response({
                    "status": 0,
                    "msg": "ok",
                    "data": user
                })
            else:
                return Response({"code": 2, "msg": "无效的token"})
        else:
            return Response({"code": 1, "msg": "缺少参数"})
            # 检测对字典排序
# WXBizDataCrypt文件，下载的解密，然后二次封装的
import base64
import json
from Crypto.Cipher import AES
from api.wx import settings
class WXBizDataCrypt:
    def __init__(self, appId, sessionKey):
        self.appId = appId
        self.sessionKey = sessionKey
    def decrypt(self, encryptedData, iv):
        # base64 decode
        sessionKey = base64.b64decode(self.sessionKey)
        encryptedData = base64.b64decode(encryptedData)
        iv = base64.b64decode(iv)
        cipher = AES.new(sessionKey, AES.MODE_CBC, iv)
        decrypted = json.loads(self._unpad(cipher.decrypt(encryptedData)))
        if decrypted['watermark']['appid'] != self.appId:
            raise Exception('Invalid Buffer')
        return decrypted
    def _unpad(self, s):
        return s[:-ord(s[len(s)-1:])]
    @classmethod
    def get_info(cls,sessionKey,encryptedData,iv):
        # appId = settings.AppId
        # sessionKey = sessionKey
        # encryptedData = encryptedData
        # iv = iv
        #
        # # 实例化这个类 WXBizDataCrypt
        # pc = cls(appId, sessionKey)
        # return pc.decrypt(encryptedData, iv)
        # 简化为：
        return cls(settings.AppId, sessionKey).decrypt(encryptedData, iv)

import pymysql
pymysql.install_as_MySQLdb()
DATABASES = {
    'default': {
        'ENGINE': 'django.db.backends.mysql',
        'NAME': 'python13',
        'USER': 'root',
        'PASSWORD': '123',
        'HOST': 'localhost',
        'PORT': 3306,
        'OPTIONS': {'charset': 'utf8mb4'},
    }
}

pip install pycryptodome