Class WeChat{           
    protected $appid;     
    protected $secret;     
    protected $accessToken;           
    function __construct(){         
        $this->appid       = "xxx";         
        $this->secret      = "xxx";         
        $this->accessToken = $this->getAccessToken();     
    }           
    /**      
       * 获取access_token      
       * token的有效时间为2小时，这里可以做下处理，提高效率不用每次都去获取，      
       * 将token存储到缓存中，每2小时更新一下，然后从缓存取即可      
       * @return      
       **/     
       private function getAccessToken(){         
           url = "https://api.weixin.qq.com/cgi-bin/token?grant_type=client_credential&appid=".$this->appid."&secret=".$this->secret;         
           $res = json_decode($this->httpRequest($url),true);         
           return $res['access_token'];     
       }          
      /**      
         * POST或GET请求      
         * @url 请求url      
         * @data POST数据      
         * @return      
         **/     
       private function httpRequest($url, $data = ""){ 
       $curl = curl_init();         
       curl_setopt($curl, CURLOPT_URL, $url);         
       curl_setopt($curl, CURLOPT_SSL_VERIFYPEER, FALSE);         
       curl_setopt($curl, CURLOPT_SSL_VERIFYHOST, FALSE);         
       if(!empty($data)){  
           //判断是否为POST请求             
           curl_setopt($curl, CURLOPT_POST, 1);             
           curl_setopt($curl, CURLOPT_POSTFIELDS, $data);         
       }         
       curl_setopt($curl, CURLOPT_RETURNTRANSFER, 1);         
       $output = curl_exec($curl);         
       curl_close($curl);         
       return $output;     
       }           
       /**      
          * 获取openID和unionId      
          * @code 微信授权登录返回的code      
          * @return      
          **/     
        public function getOpenIdOrUnionId($code){         
            $url = "https://api.weixin.qq.com/sns/oauth2/access_token?appid=".$this->appid."&secret=".$this->secret."&code=".$code."&grant_type=authorization_code";         
            $data = $this->httpRequest($url);         
            return $data;     
        }           
        /**      
           * 通过openId获取用户信息      
           * @openId      
           * @return      
           **/     
         public function getUserInfo($openId){         
              $url  = "https://api.weixin.qq.com/cgi-bin/user/info?access_token=".$this->accessToken."&openid=".$openId."&lang=zh_CN";         
              $data = $this->httpRequest($url);         
              return $data;     
          }           
         /**      
            * 发送模板短信      
            * @data 请求数据      
            * @return      
            **/     
            public function sendTemplateMessage($data = ""){         
                $url = "https://api.weixin.qq.com/cgi-bin/message/template/send?access_token=".$this->accessToken; 
                $result = $this->httpRequest($url, $data);        
                 return $result;     
             }          
          /**     
             * 生成带参数的二维码      
             * @scene_id 自定义参数（整型）      
             * @return      
             **/     
             public function getQrcode($scene_id){         
                 $url = "https://api.weixin.qq.com/cgi-bin/qrcode/create?access_token=".$this->accessToken;         
                 $data = array(             
                     "expire_seconds" => 3600, //二维码的有效时间（1小时）             
                     "action_name" => "QR_SCENE",             
                     "action_info" => array("scene" => array("scene_id" => $scene_id))         
                 );         
                 $result = $this->httpRequest($url, json_encode($data));         
                 return $result;     
             }           
           /**      
              * 生成带参数的二维码      
              * @scene_str 自定义参数（字符串）      
              * @return      
              **/     
              public function getQrcodeByStr($scene_str){         
                  $url = "https://api.weixin.qq.com/cgi-bin/qrcode/create?access_token=".$this->accessToken;         
                  $data = array(             
                      "expire_seconds" => 3600, //二维码的有效时间（1小时）             
                      "action_name" => "QR_STR_SCENE",             
                      "action_info" => array("scene" => array("scene_str" => $scene_str))         
                  );         
                  $result = $this->httpRequest($url, json_encode($data));         
                  return $result;     
              }           
           /**      
              * 换取二维码      
              * @ticket      
              * @return      
              **/     
              public function generateQrcode($ticket){         
                  return "https://mp.weixin.qq.com/cgi-bin/showqrcode?ticket=".$ticket;     
              }           
           /**     
              * 回调函数      
              **/     
              public function callback(){         
                  $callbackXml = file_get_contents('php://input'); //获取返回的xml         
                  //下面是返回的xml         
                  //<xml><ToUserName><![CDATA[gh_f6b4da984c87]]></ToUserName> 
                  //微信公众号的微信号         
                  //<FromUserName><![CDATA[oJxRO1Y2NgWJ9gMDyE3LwAYUNdAs]]></FromUserName> 
                  //openid用于获取用户信息，做登录使用         
                  //<CreateTime>1531130986</CreateTime> 
                  //回调时间         //<MsgType><![CDATA[event]]></MsgType>         
                  //<Event><![CDATA[SCAN]]></Event>         
                  //<EventKey><![CDATA[lrfun1531453236]]></EventKey> 
                  //上面自定义的参数（scene_str）         
                  //<Ticket><![CDATA[gQF57zwAAAAAAAAAAS5odHRwOi8vd2VpeGluLnFxLmNvbS9xLzAyY2ljbjB3RGtkZWwxbExLY3hyMVMAAgTvM0NbAwSAOgkA]]></Ticket> 
                  //换取二维码的ticket         //</xml>         $data = json_decode(json_encode(simplexml_load_string($callbackXml, 'SimpleXMLElement', LIBXML_NOCDATA)), true); 
                  //将返回的xml转为数组         
                  if(count($data)){             
                      $userInfo = $this->getUserInfo($data['FromUserName']); //获取用户信息             
                      //这里把返回的数据写入数据库（注：务必将“EventKey”也存到数据表中，后面检测登录需用到此唯一值查询记录）             
                      //用于前台做检测该用户扫码之后是否有关注公众号，关注了就自动登录网站             
                      //原理：前台通过自定义的参数（最好设成值唯一）查询数据标是否有此记录，若有则登录。         
                  }     
              } 
  }

＜?php    
     header("Content-type:text/html;charset=utf-8");
     require_once('WeChat.class.php');
     $WeChat = new WeChat();
     $scene_str = "lrfun1531453236"; //"lrfun" . time(); //这里建议设唯一值(如：随机字符串+时间戳)
     $result = json_decode($WeChat->getQrcodeByStr($scene_str), true);
     $qrcode = $WeChat->generateQrcode($result['ticket']); //生成二维码
         
     echo "自定义参数：".$scene_str;
     echo "＜br/＞＜img src="$qrcode"＞";?＞
＜script type="text/javascript" src="http://www.lrfun.com/statics/fun2/js/jquery.min.js"＞＜/script＞
＜script type="text/javascript"＞    setInterval("checkLogin()", 2000); //每2秒发送一次请求
     function checkLogin(){
        $.post("checkLogin.php", {scene_str:"＜?=$scene_str?＞"}, function(data){
             if(data){
                    //做逻辑判断，登录跳转
             }
        },"Json");
    }
＜/script＞

// 调取回调函数
require_once('WeChat.class.php');
$WeChat = new WeChat();
$result = $WeChat->callback();

if(isset($_POST['scene_str']) && $_POST['scene_str']){
   //根据scene_str查询数据库，是否有此记录
   echo "true";
}else{
   echo "false";
}