1.通过后端站点http://b.cn  跳转至前端链接 http://aa.cn/v1/demo/demo

    public function index(){$ident=input('ident');$this->redirect('http://aa.cn/?ident='.$ident);}

2.前端http://aa.cn 再跳转到后端 https://c.com(此域名绑定微信公众号:需备案)

onShow() {console.log('URL参数111:', this.identValue);uni.redirectTo({url: '/pages/index/webview/webview?url=' + encodeURIComponent('https://c.com/v1/demo/demo?ident='+this.identValue)});var ua = window.navigator.userAgent.toLowerCase();console.log(ua);},

3.https://c.com (用此域名获取微信用户openid) 然后在跳转到前端域名

    public function demo(){$ident=input('ident');Checking::writeLog('ident:'.$ident,'input','wx.log');$wechat=new Wechat();$user=$wechat->getUserOpenId();Checking::writeLog(json_encode($user,JSON_UNESCAPED_UNICODE),'openid','wx.log');$this->redirect('http://aa.cn/#/pages/index/home?ident='.$ident.'&openid='.$user);halt($user);}

<?php
/*** Created by PhpStorm.* User: Administrator* Date: 2018/8/6* Time: 22:41*/namespace app\v1\controller;
use app\common\controller\Checking;
use think\Controller;class Wechat extends Controller
{protected $accessTokenUrl = 'https://api.weixin.qq.com/cgi-bin/token';protected $wechatAuthCodeUrl = 'https://open.weixin.qq.com/connect/oauth2/authorize?';protected $userOpenIdUrl = 'https://api.weixin.qq.com/sns/oauth2/access_token?';protected $appId;protected $secret;protected $code;protected $openId;/*** 加载微信配置*/protected function _initialize(){$this->appId = '';$this->secret = '';}/*** 作用：格式化参数，签名过程需要使用* @param $paraMap* @param $urlencode* @return bool|string*/protected function formatBizQueryParaMap($paraMap, $urlencode){$buff = "";ksort($paraMap);foreach ($paraMap as $k => $v){if($urlencode){$v = urlencode($v);}$buff .= $k . "=" . $v . "&";}$reqPar = '';if (strlen($buff) > 0){$reqPar = substr($buff, 0, strlen($buff)-1);}return $reqPar;}/*** 网页授权获取用户openId -- 1.获取授权code url*/public function getWechatAuthCode(){// 获取来源地址$url = $this->get_url();// 获取code$urlObj["appid"] = $this->appId;$urlObj["redirect_uri"] = "$url";$urlObj["response_type"] = "code";$urlObj["scope"] = "snsapi_base";$urlObj["state"] = "STATE"."#wechat_redirect";$bizString = $this->formatBizQueryParaMap($urlObj, false);$codeUrl =  $this->wechatAuthCodeUrl.$bizString;return $codeUrl;}/*** 网页授权获取用户openId -- 2.获取openid* @return mixed*/public function getUserOpenId(){if (!isset($_GET['code'])){$codeUrl = $this->getWechatAuthCode();Header("Location: $codeUrl");die;}else{$code = $_GET['code'];$this->code = $code;// 请求openid$param = ['appid'     =>  $this->appId,'secret'    =>  $this->secret,'code'      =>  $this->code,'grant_type'=>  "authorization_code",];$user_info = $this->curl($this->userOpenIdUrl.http_build_query($param).'&lang=zh_CN');//取出openid$data = json_decode($user_info,true);$this->openId = $data['openid'];return $this->openId;}}/*** 获取来源地址* @return string*/public function get_url() {//获取来源地址$url = "http://".$_SERVER["HTTP_HOST"].$_SERVER["REQUEST_URI"];return $url;}// php CURL请求public function curl($url, $post = false){$ch = curl_init();curl_setopt($ch, CURLOPT_URL, $url);curl_setopt($ch, CURLOPT_HEADER, 0);curl_setopt($ch, CURLOPT_RETURNTRANSFER, 1);if ($post) {curl_setopt($ch, CURLOPT_POST, 1);curl_setopt($ch, CURLOPT_POSTFIELDS, $post);}$result = curl_exec($ch);curl_close($ch);return $result;}}