$curl = curl_init();
curl_setopt($curl, CURLOPT_URL, $url);
curl_setopt($curl, CURLOPT_RETURNTRANSFER, true);
curl_setopt($curl, CURLOPT_WRITEFUNCTION, 'func');//设置一个回调函数
$text = curl_exec($curl);
curl_close($curl);
echo $text;

function func($ch, $str) {
  if(strstr($str, '你需要识别的串') return 0;//判断是否取到需要的内容
  return strlen($str);
}