$url = $photo;    //图片路径
$path = '../';    //保存路径
$fileName = "photo.png";  //保存图片名
$ch = curl_init();
  curl_setopt($ch, CURLOPT_SSL_VERIFYPEER, false); // 信任任何证书
  curl_setopt($ch, CURLOPT_URL, $url);
  curl_setopt($ch, CURLOPT_RETURNTRANSFER, 1);
  curl_setopt($ch, CURLOPT_CONNECTTIMEOUT, 30);
  $file = curl_exec($ch);
  curl_close($ch);
  unlink('../photo.png'); //删除原有图片
  $resource = fopen($path . $fileName , 'a');
  fwrite($resource, $file);
  fclose($resource);