思路：

1钉鸯、小程序端獲取用戶ID吧史，發(fā)送至后臺
2、后臺查詢用戶ID唠雕，如果找到了該用戶贸营，返回Token，沒找到該用戶岩睁，保存到數(shù)據(jù)庫钞脂，并返回Token

小程序端如何獲取用戶ID：

小程序端 wx.getUserInfo() 可以獲取到用戶信息

wx.getUserInfo()

解密 encryptedData

auth.code2Session接口

注意：調(diào)用 wx.getUserInfo() 需要用戶授權(quán)

app.js

App({
  data: {
    canIUse: wx.canIUse('button.open-type.getUserInfo'), //版本兼容
    serverHost: 'http://localhost:8090/',
    token: null,
    userInfo: null,
  },
  onLaunch: function() {
    this.autoLogin();
  },
  //自動登錄
  autoLogin: function() {
    var that = this;
    //查有沒有緩存 token, 緩存可能被清空
    wx.getStorage({
      key: 'token',
      // 有token, 到后臺檢查 token 是否過期
      success(res) {
        console.log("token: " + res.data);
        that.checkToken(res.data);
      },
      // 沒有緩存token, 需要登錄
      fail(e) {
        console.log("not saved token, login...");
        that.userLogin();
      }
    })
  },
  //檢查 token 是否過期
  checkToken: function(token) {
    var that = this;
    wx.request({
      url: that.data.serverHost + 'user/token/check',
      method: 'POST',
      data: {
        token: token,
      },
      header: {
        "Content-Type": "application/x-www-form-urlencoded"
      },
      success(res) {
        if (res.data.code == 10000) {
          console.log("token not expired");
        } else {
          console.log("token expired, refresh...");
          // 去后臺刷新 token
          that.refreshToken();
        }
      },
      fail(e) {
        console.error(e);
        console.error("【check token failed, login...】");
        // 走登錄流程
        that.userLogin();
      }
    })
  },
  //刷新 token
  refreshToken: function() {
    var that = this;
    //查有沒有緩存 refreshtoken, 緩存可能被清空
    wx.getStorage({
      key: 'refreshtoken',
      // 有refreshtoken, 到后臺刷新 token
      success(res) {
        console.log("refreshtoken: " + res.data);
        that.refreshToken2(res.data);
      },
      // 沒有緩存refreshtoken, 需要登錄
      fail(e) {
        console.log("not saved refreshtoken, login...");
        that.userLogin();
      }
    })
  },
  //去后臺刷新 token
  refreshToken2: function(refreshtoken) {
    var that = this;
    wx.request({
      url: that.data.serverHost + 'user/token/refresh',
      method: 'POST',
      data: {
        refreshtoken: refreshtoken,
      },
      header: {
        "Content-Type": "application/x-www-form-urlencoded"
      },
      success(res) {
        if (res.data.code == 10000 && res.data.data.token) {
          console.log(res.data.data.token);
          that.saveToken(res.data.data.token)
        } else {
          console.log("refresh token failed, login...");
          that.userLogin();
        }
      },
      fail(e) {
        console.error(e);
        console.error("【refresh token failed, login...】");
        that.userLogin();
      }
    })

  },
  // wx.login 獲取 code,
  // wx.getUserInfo 獲取 encryptedData 和 iv
  // 去后臺換取 token
  userLogin: function() {
    var that = this;
    // wx.login 獲取 code,
    wx.login({
      success(res) {
        if (res.code) {
          console.log("code:" + res.code);
          that.userLogin2(res.code);
        } else {
          console.error("【wx login failed】");
        }
      },
      fail(e) {
        console.error(e);
        console.error("【wx login failed】");
      }
    })

  },
  // 檢查授權(quán), wx.getUserInfo
  userLogin2: function(code) {
    var that = this;
    // 檢查是否授權(quán)
    wx.getSetting({
      success(res) {
        // 已經(jīng)授權(quán), 可以直接調(diào)用 getUserInfo 獲取頭像昵稱
        if (res.authSetting['scope.userInfo']) {
          that.userLogin3(code);
        } else { //沒有授權(quán) 
          if (that.data.canIUse) {
            // 高版本, 需要轉(zhuǎn)到授權(quán)頁面 
            wx.navigateTo({
              url: '/pages/auth/auth?code=' + code,
            });
          } else {
            //低版本, 調(diào)用 getUserInfo, 系統(tǒng)自動彈出授權(quán)對話框
            that.userLogin3(code);
          }
        }
      }
    })
  },
  // wx.getUserInfo
  userLogin3: function(code) {
    var that = this;
    wx.getUserInfo({
      success: function(res) {
        console.log(res);
        if (res.userInfo) {
          that.data.userInfo = res.userInfo;
        }
        if (code && res.encryptedData && res.iv) {
          that.userLogin4(code, res.encryptedData, res.iv);
        } else {
          console.error("【wx getUserInfo failed】");
        }
      },
      fail(e) {
        console.error(e);
        console.error("【wx getUserInfo failed】");
      }
    })
  },
  //去后臺獲取用戶 token
  userLogin4: function(code, data, iv) {
    var that = this;
    wx.request({
      url: that.data.serverHost + 'user/wxlogin',
      method: 'POST',
      data: {
        code: code,
        data: data,
        iv: iv,
      },
      header: {
        "Content-Type": "application/x-www-form-urlencoded"
      },
      success(res) {
        console.log(res)
        if (res.data.code == 10000) {
          if (res.data.data.token) {
            console.log(res.data.data.token);
            that.saveToken(res.data.data.token);
          } else {
            console.error("【userLogin token failed】")
          }
          if (res.data.data.refreshtoken) {
            console.log(res.data.data.refreshtoken);
            wx.setStorage({
              key: "refreshtoken",
              data: res.data.data.refreshtoken
            });
          } else {
            console.error("【userLogin refreshtoken failed】")
          }
        } else {
          console.error("【userLogin failed】")
        }

      },
      fail(e) {
        console.error(e);
        console.error("【userLogin failed】");
      }
    })
  },
  // 保存 token
  saveToken: function(token) {
    this.data.token = token;
    wx.setStorage({
      key: "token",
      data: token
    });
  },
  getUserInfo: function(call) {
    var that = this
    if (this.data.userInfo) {
      call(this.data.userInfo);
    } else {
      // 先從緩存查 userInfo, 緩存可能被清空,
      wx.getStorage({
        key: 'userInfo',
        success(res) {
          console.log(res.data);
          call(res.data);
          that.setData({
            userInfo: res.data
          });
        },
        fail(res) {
          console.log("not save userInfo, wx getUserInfo...");
          wx.getUserInfo({
            success(res) {
              console.log(userInfo);
              if (res.userInfo) {
                call(res.userInfo);
                that.setData({
                  userInfo: res.userInfo
                });
              }
            }
          })
        }
      })
    }
  },
})

auth.js

const app = getApp()
Page({
  data: {
    userInfo: {
      avatarUrl: '/image/user_avarta.png',
      nickName: '昵稱'
    },
  },
  onLoad: function(param) {
    this.data.code = param.code
  },
  getUserInfo: function(res) {
    console.log(res.detail)
    app.data.userInfo = res.detail.userInfo
    this.setData({
      userInfo: res.detail.userInfo,
    })
    if (this.data.code && res.detail.encryptedData && res.detail.iv) {
      app.userLogin4(this.data.code, res.detail.encryptedData, res.detail.iv)
    } else {
      console.error("【getUserInfo失敗】");
    }
  }
})

授權(quán)頁面:auth.wxml

<view class="container">
  <text class="prompt">授權(quán)登錄</text>
  <view class="userinfo">
    <image class="userinfo-avatar" src="{{userInfo.avatarUrl}}" mode="cover"></image>
    <text class="userinfo-nickname">{{userInfo.nickName}}</text>
  </view>
  <button open-type="getUserInfo" bindgetuserinfo="getUserInfo" type="primary"> 授權(quán)登錄 </button>
</view>

后端代碼

后端使用Python + Django 框架實現(xiàn)：
安裝 requests ，發(fā)送Http請求
安裝 pycryptodome曼库，解密

pip install requests 
pip install pycryptodome

此處僅給出View的代碼

import hashlib
import time
import json

import requests
from django.conf import settings
from django.http import JsonResponse
from django.views import View
from django_redis import get_redis_connection

from user.models import UserInfo
from utils.WXBizDataCrypt import WXBizDataCrypt


class WxLoginView(View):
    def post(self, request):
        post = request.POST
        code = post.get('code')
        if not code:
            return JsonResponse({'code': 10001, 'msg': 'missing parameter: code'})

        url = "https://api.weixin.qq.com/sns/jscode2session?appid={0}&secret={1}&js_code={2}&grant_type=authorization_code" \
            .format(settings.WX_APP_ID, settings.WX_APP_KEY, code)
        # 發(fā)送GET請求
        wx_res = requests.get(url)
        errcode = wx_res['errcode'] if 'errcode' in wx_res else None
        if errcode:
            return JsonResponse({'code': 13001, 'msg': 'wx_auth.code2Session:' + wx_res.errmsg})

        wx_session = json.loads(wx_res.text)
        unionid = wx_session['unionId'] if 'unionId' in wx_session else None
        decrypt = False
        user = None
        if not unionid:
            decrypt = True
        else:
            user = UserInfo.objects.get(wx_unionid=unionid)
            # 判斷用戶是否第一次登錄
            if not user:
                decrypt = True
        # 解密 encryptedData
        if decrypt:
            encrypted_data = post.get('data')
            iv = post.get('iv')
            if not all([encrypted_data, iv]):
                return JsonResponse({'code': 10001, 'msg': 'missing parameter: data,iv'})

            session_key = wx_session['session_key'] if 'session_key' in wx_session else None
            if not session_key:
                return JsonResponse({'code': 13001, 'msg': 'wx_auth.code2Session:' + 'no session_key'})

            pc = WXBizDataCrypt(settings.WX_APP_ID, session_key)
            wx_user = pc.decrypt(encrypted_data, iv)
            unionid = wx_user['unionId']

            user = UserInfo.objects.get(wx_unionid=unionid)
            # 判斷用戶是否第一次登錄
            if not user:
                # 微信用戶第一次登錄,創(chuàng)建用戶
                username = 'wx_' + unionid
                nickname = wx_user['nickName']
                avatar = wx_user['avatarUrl']
                gender = wx_user['gender']
                country = wx_user['country']
                province = wx_user['province']
                city = wx_user['city']
                language = wx_user['language']
                user = UserInfo.objects.create(username=username,
                                               wx_unionid=unionid,
                                               nickname=nickname,
                                               avatar=avatar,
                                               gender=gender,
                                               country=country,
                                               province=province,
                                               city=city,
                                               language=language,
                                               )

        # 生成 token
        md5 = hashlib.md5()
        bstr = (unionid + str(time.time())).encode(encoding='utf-8')
        md5.update(bstr)
        token = md5.hexdigest()
        bstr = ("refresh" + unionid + str(time.time())).encode(encoding='utf-8')
        md5.update(bstr)
        refreshtoken = md5.hexdigest()
        # 存入Redis
        conn = get_redis_connection('default')
        conn.set(token, unionid)
        conn.expire(token, 5)
        conn.set(refreshtoken, unionid)
        conn.expire(refreshtoken, 3600 * 24 * 7)
        data = {'token': token, 'expire': 3600, 'refreshtoken': refreshtoken}
        return JsonResponse({'code': 10000, 'msg': 'ok', 'data': data})


class TokenCheckView(View):
    def post(self, request):
        post = request.POST
        token = post.get('token')
        if not token:
            return JsonResponse({'code': 10001, 'msg': 'missing parameter: token'})

        conn = get_redis_connection('default')
        exist = conn.ttl(token)
        if exist < 0:
            return JsonResponse({'code': 10200, 'msg': 'token expired'})
        else:
            return JsonResponse({'code': 10000, 'msg': 'ok'})


class TokenRefreshView(View):
    def post(self, request):
        post = request.POST
        refreshtoken = post.get('refreshtoken')
        if not refreshtoken:
            return JsonResponse({'code': 10001, 'msg': 'missing parameter: refreshtoken'})

        conn = get_redis_connection('default')
        unionid = conn.get(refreshtoken)
        if not unionid:
            return JsonResponse({'code': 10200, 'msg': 'refreshtoken expired'})

        # 生成 token
        md5 = hashlib.md5()
        bstr = unionid + str(time.time()).encode(encoding='utf-8')
        md5.update(bstr)
        token = md5.hexdigest()
        conn.set(token, unionid)
        conn.expire(token, 5)
        data = {'token': token}
        return JsonResponse({'code': 10000, 'msg': 'ok', 'data': data})

注意：

如果解壓之后区岗，沒有獲取到 UnionID ，請登錄 微信開放平臺 => 管理中心 => 綁定小程序

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