/** 
 * 首先创建二维码ticket 
 * @param string $sceneid 场景值ID 
 * @param string $type 值为'temp'的时候生成临时二维码 
 * @param string $expire_seconds 二维码过期时间 
 * @return string 二维码ticket 
 */ 
public function _getTicket($sceneid,$type='temp',$expire_seconds=604800){ 
 if($type=='temp'){ 
  $data = '{"expire_seconds": %s, "action_name": "QR_SCENE", "action_info": {"scene": {"scene_id": %s}}}'; 
  $data = sprintf($data,$expire_seconds,$sceneid); 
 }else{ 
  $data = '{"action_name": "QR_LIMIT_SCENE", "action_info": {"scene": {"scene_id": %s}}}'; 
  $data = sprintf($data,$sceneid); 
 } 
 $curl = 'https://api.weixin.qq.com/cgi-bin/qrcode/create?access_token='.$this->_getAccessToken(); 
 $content = $this->_request($curl,true,'POST',$data); 
 $cont = json_decode($content); 
  
 return $cont->ticket; 
} 

//然后凭借ticket到指定URL换取二维码 
public function _getQRCode($sceneid,$type='temp',$expire_seconds=604800){ 
 $ticket = $this->_getTicket($sceneid,$type,$expire_seconds); 
 $curl = 'https://mp.weixin.qq.com/cgi-bin/showqrcode?ticket='.urlencode($ticket); 
 $content = $this->_request($curl); 
 return $content; 
} 

header('Content-type:image.jpeg'); 
$result = $wechat->_getQRCode(30); 
echo $result;