PHP 获取短链等接跳转后的真实地址

//1、用get_headers函数  php自带的get_headers函数可以获取服务器响应一个HTTP请求所发送的所有标头
function get_redirect_url_by_header($url)
{
  $header = get_headers($url, 1);
  if (strpos($header[0], '301') !== false || strpos($header[0], '302') !== false) {
    if (is_array($header['Location'])) {
      return $header['Location'][count($header['Location']) - 1];
    } else {
      return $header['Location'];
    }
  } else {
    return $url;
  }
}

//2、使用cURL函数
function get_redirect_url_by_curl($url, $referer = '', $timeout = 10)
{
  $redirect_url = false;
  $ch = curl_init();
  curl_setopt($ch, CURLOPT_URL, $url);
  curl_setopt($ch, CURLOPT_HEADER, TRUE);
  curl_setopt($ch, CURLOPT_NOBODY, TRUE);//不返回请求体内容
  curl_setopt($ch, CURLOPT_FOLLOWLOCATION, TRUE);//允许请求的链接跳转
  curl_setopt($ch, CURLOPT_RETURNTRANSFER, TRUE);
  curl_setopt($ch, CURLOPT_TIMEOUT, $timeout);
  curl_setopt($ch, CURLOPT_HTTPHEADER, array('Accept: */*', 'User-Agent: Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.1; SV1)', 'Connection: Keep-Alive'));
  if ($referer) curl_setopt($ch, CURLOPT_REFERER, $referer);//设置referer
  $content = curl_exec($ch);
  if (!curl_errno($ch)) {
    $redirect_url = curl_getinfo($ch, CURLINFO_EFFECTIVE_URL);//获取最终请求的url地址
  }
  return $redirect_url;
}

$headers = get_headers($url, TRUE);
var_dump($headers);