解决办法

制作微信回调中转器，通过授权给中转器实现，多域名分发跳转

中转域名 http://transfer.example.com/ 下的php

<?php
namespace app\index\controller;

use app\BaseController;
use think\facade\View;
use think\facade\Db;
use think\facade\Cache;
class Wechat extends BaseController
{
    public $arrayurl=['http://aa.example.com/rep','http://bb.example.com/index/wechat/rep'];
    public $arraytype=['infoh5'];
    public $APPID = "xxx";
    public $SECRET = "xxx";
    //授权登录
    public function actionScopeRedirectUriAppid(){
        $tourl=input('tourl');
        if(empty($tourl)||!in_array($tourl,$this->arrayurl)){
            exit('非法路径');
        }
        $type=input('type');
        if(empty($type)||!in_array($type,$this->arraytype)){
            exit('非法操作');
        }
        $REDIRECT_URI=  'http://'.$_SERVER['HTTP_HOST'].'/index/wechat/actionWeixinOpenidCallback?tourl='.$tourl.'&&type='.$type;
        $scope='snsapi_userinfo';  //手动授权snsapi_userinfo   静默授权snsapi_base
        $url='https://open.weixin.qq.com/connect/oauth2/authorize?appid='.$this->APPID.'&redirect_uri='.urlencode($REDIRECT_URI).'&response_type=code&scope='.$scope.'&state=scene#wechat_redirect';
        header("Location:{$url}");
        die();
    }
    ##微信回调,获取openid
    public function actionWeixinOpenidCallback(){
        $tourl=input('tourl');
        if(empty($tourl)||!in_array($tourl,$this->arrayurl)){
            exit('非法路径');
        }
        $type=input('type');
        if(empty($type)||!in_array($type,$this->arraytype)){
            exit('非法操作');
        }
        if($code= input('code')){
            //h5的access_token
            $url = "https://api.weixin.qq.com/sns/oauth2/access_token?appid={$this->APPID}&secret={$this->SECRET}&code={$code}&grant_type=authorization_code";
            $UserOpenidArr = json_decode($this->dogetCurl($url),1);
            if(empty($UserOpenidArr ['openid']) ) {
                print_r( $UserOpenidArr );
                die("授权失败");
            }
            $openid=$UserOpenidArr ['openid'];
            session('openid',$openid);
            \think\facade\Session::save();
            session('access_token',$UserOpenidArr['access_token']);
            \think\facade\Session::save();
            
            
            $openid=session('openid');
            $access_token=session('access_token');
            $token=$this -> getAccessToken();
            
            if($type=="infoh5"){
                //跳转h5获取用户信息
                header("Location:http://transfer.example.com/index/wechat/actionWeixinOpenidGetUserInfo?openid={$openid}&&access_token={$access_token}&&tourl={$tourl}" );
            }
            
            die();
        }else{
            die("微信授权失败");
        }
    }
    
    
    //h5获取用户信息
    public function actionWeixinOpenidGetUserInfo(){
        $tourl=input('tourl');
        if(empty($tourl)||!in_array($tourl,$this->arrayurl)){
            exit('非法路径');
        }
        $openid= input('openid');
        $access_token=input('access_token');
        $res=$this->getapktj("https://api.weixin.qq.com/sns/userinfo?access_token={$access_token}&openid={$openid}&lang=zh_CN");
        $res['nickname']=preg_replace('/[\x{10000}-\x{10FFFF}]/u', '', $res['nickname']);
        $res['access_token']=$access_token;
        $res['token']=$this ->getAccessToken();
        $res=http_build_query($res);
        header("Location:{$tourl}?$res");
        die();
        
    }
    
    //跨服务器高级用法
    public function getapktj($url){
    	 
		 $method ="GET";
		 $curl = curl_init();
		 curl_setopt($curl, CURLOPT_CUSTOMREQUEST, $method);
		 curl_setopt($curl, CURLOPT_URL, $url);
		 curl_setopt($curl, CURLOPT_FAILONERROR, false);
		 curl_setopt($curl, CURLOPT_RETURNTRANSFER, true);
		 curl_setopt($curl, CURLOPT_HEADER, false);
	
		$ret = curl_exec($curl);
		$all=json_decode($ret,true);
    	return $all;
    //返回数组
    }
    
    
    public function getAccessToken(){
        if(!Cache::get("token")){
            
            //公众号的access_token
            $url = "https://api.weixin.qq.com/cgi-bin/token?grant_type=client_credential&appid={$this->APPID}&secret={$this->SECRET}";
            $UserOpenidArrcgi = json_decode($this->dogetCurl($url),1);
            $token=$UserOpenidArrcgi['access_token'];
            Cache::set('token',$token,4800);
            
            
        }
        $accessToken = Cache::get("token");
        return $accessToken;
    }
    
    
	
   
}

回调目标域名http://aa.example.com 下的php下的方法

public function checklogin(){
if(!session('openid')||!session('access_token')||!Cache::get("token")){ header("Location:http://rep.zlhdsg.com/index/wechat/actionScopeRedirectUriAppid?tourl=http://sg.zlhdsg.com/index/wechat/rep&&type=infoh5");
             die();
            }
}

public function rep(){
        $res=input("get.");
        
        $id=Db::table("users")->where("openid",$res['openid'])->value("id");
        if($id){
            $res1=Db::table("users")->where('id',$id)->update(['nickname'=>$res['nickname'],'headimgurl'=>$res['headimgurl'],'updated_at'=>date("Y-m-d H:i:s")]);
        }else{
            $id=$res1=Db::table("users")->insertGetId(['openid'=>$res['openid'],'nickname'=>$res['nickname'],'headimgurl'=>$res['headimgurl'],'created_at'=>date("Y-m-d H:i:s"),'updated_at'=>date("Y-m-d H:i:s")]);
        }
        session('openid',$res['openid']);
        \think\facade\Session::save();
        session('access_token',$res['access_token']);
        \think\facade\Session::save();
        Cache::set('token',$res['token'],4800);
        if($res1){
            $this->redirect(url("index/index"));
        }else{
            echo "error";
        }
    }

配置个中转用的，多个项目共用一个。