Determine whether the page or image has been compressed by gzip through php

<?phpob_start(&#39;ob_gzhandler&#39;); // 开启gzip，屏蔽则关闭$data = array(    array(&#39;name&#39;=>&#39;one&#39;,&#39;value&#39;=>1),    array(&#39;name&#39;=>&#39;two&#39;,&#39;value&#39;=>2),    array(&#39;name&#39;=>&#39;three&#39;,&#39;value&#39;=>3)
);

header(&#39;content-type:application/json&#39;);echo json_encode($data);?>

<?php$url = &#39;http://www.example.com/&#39;;
var_dump(check_gzip($url));/**
 * 判断url是否经过gzip压缩
 * @param String  $url 来源
 * @param Boolean
 */function check_gzip($url){
    $header = get_headers($url, 1);    if(isset($header[&#39;Vary&#39;]) && $header[&#39;Vary&#39;]==&#39;Accept-Encoding&#39;){        return true;
    }    return false;
}?>

<?phpheader(&#39;content-type:image/jpeg&#39;);
ob_start(&#39;ob_gzhandler&#39;); // 开启gzip，屏蔽则关闭echo file_get_contents(&#39;test.jpg&#39;);?>

<?php$url = &#39;http://www.example.com/&#39;;
var_dump(check_gzip($url));/**
 * 判断url是否经过gzip压缩
 * @param String  $url 来源
 * @param Boolean
 */function check_gzip($url){
    $ch = curl_init();
    curl_setopt($ch, CURLOPT_URL, $url);
    curl_setopt($ch, CURLOPT_HEADER, 1);         // 输出header信息
    curl_setopt($ch, CURLOPT_RETURNTRANSFER, 1); // 返回的信息不直接输出
    curl_setopt($ch, CURLOPT_ENCODING, &#39;&#39;);      // 不限制编码类型
    $response = curl_exec($ch);    if(!curl_errno($ch)){        $info = curl_getinfo($ch);        // 获取header
        $header_size = $info[&#39;header_size&#39;];        $header_str = substr($response, 0, $header_size);        $filter = array("\r\n", "\r");        $header_str = str_replace($filter, PHP_EOL, $header_str);        // 检查content-encoding
        preg_match(&#39;/Content-Encoding: (.*)\s/i&#39;, $header_str, $matches);        if(isset($matches[1]) && $matches[1]==&#39;gzip&#39;){            return true;
        }
    }    return false;
}?>