1、参考：在 PHP 中基于 HTTP 协议检测文件的大小(即不下载文件的情况下，获取远程文件的大小)，之前的实现，使用文件系统函数 fopen — 打开文件或者 URL。如果文件的网址需要 301 跳转，则不能够获取到文件的真实大小。如图1
PHP
<?php
function remote_filesize($url) {
static $regex = '/^Content-Length: *+\K\d++$/im';
// 将 $url 指定的名字资源绑定到一个流上，只读方式打开，将文件指针指向文件头
if (!$fp = @fopen($url, 'rb')) {
return 0;
}
// 执行 fopen() 时可以使用变量 $http_response_header。其中包含响应标头的数组。
if (
isset($http_response_header) &&
preg_match($regex, implode("\n", $http_response_header), $matches)
) {
print_r($http_response_header);
return (int)$matches[0];
}
return 0;
}
$startTime = microtime(true);
$url = 'https://media.shuijingwanwq.com/2021/07/ChinaJoy 2015 上海 梦幻西游.mp4';
echo remote_filesize($url) . "\n";
$endTime = microtime(true);
echo '耗费时间：' . ($endTime - $startTime) . '秒';
?>Plaintext
Array
(
[0] => HTTP/1.1 301 Moved Permanently
[1] => Server: nginx
[2] => Date: Tue, 10 Aug 2021 05:16:59 GMT
[3] => Content-Type: text/html
[4] => Content-Length: 162
[5] => Connection: close
[6] => Location: https://media.shuijingwanwq.com/2021/07/ChinaJoy 2015 上海 梦幻西游.mp4
[7] => Strict-Transport-Security: max-age=15768000
[8] => HTTP/1.1 200 OK
[9] => Server: nginx
[10] => Date: Tue, 10 Aug 2021 05:17:00 GMT
[11] => Content-Type: video/mp4
[12] => Content-Length: 123596884
[13] => Last-Modified: Tue, 04 Dec 2018 06:27:23 GMT
[14] => Connection: close
[15] => ETag: "5c061e4b-75df054"
[16] => Expires: Thu, 09 Sep 2021 05:17:00 GMT
[17] => Cache-Control: max-age=2592000
[18] => Strict-Transport-Security: max-age=15768000
[19] => Accept-Ranges: bytes
)
162
耗费时间：0.34205508232117秒
2、参考网址：https://www.php.net/manual/zh/function.get-headers 。决定使用 URL 函数 get_headers() 返回一个数组，包含有服务器响应一个 HTTP 请求所发送的标头。
3、新的实现方案，其代码更为简洁，且耗费时间更短。不过如果文件的网址需要 301 跳转，则不能够获取到文件的真实大小的问题仍然存在。如图2
PHP
<?php
function remote_filesize($url) {
// 返回一个数组，包含有服务器响应一个 HTTP 请求所发送的标头。
$headers = get_headers($url, 1);
if ($headers !== false && isset($headers['Content-Length'][0])) {
print_r($headers);
return $headers['Content-Length'][0];
}
return 0;
}
$startTime = microtime(true);
$url = 'https://media.shuijingwanwq.com/2021/07/ChinaJoy 2015 上海 梦幻西游.mp4';
echo remote_filesize($url) . "\n";
$endTime = microtime(true);
echo '耗费时间：' . ($endTime - $startTime) . '秒';
?>Plaintext
Array
(
[0] => HTTP/1.1 301 Moved Permanently
[Server] => Array
(
[0] => nginx
[1] => nginx
)
[Date] => Array
(
[0] => Tue, 10 Aug 2021 05:48:21 GMT
[1] => Tue, 10 Aug 2021 05:48:21 GMT
)
[Content-Type] => Array
(
[0] => text/html
[1] => video/mp4
)
[Content-Length] => Array
(
[0] => 162
[1] => 123596884
)
[Connection] => Array
(
[0] => close
[1] => close
)
[Location] => https://media.shuijingwanwq.com/2021/07/ChinaJoy 2015 上海 梦幻西游.mp4
[Strict-Transport-Security] => Array
(
[0] => max-age=15768000
[1] => max-age=15768000
)
[1] => HTTP/1.1 200 OK
[Last-Modified] => Tue, 04 Dec 2018 06:27:23 GMT
[ETag] => "5c061e4b-75df054"
[Expires] => Thu, 09 Sep 2021 05:48:21 GMT
[Cache-Control] => max-age=2592000
[Accept-Ranges] => bytes
)
162
耗费时间：0.27841401100159秒
4、新的实现方案，如果文件的网址不需要 301 跳转，则不存在：Location 。如图3
Plaintext
Array
(
[0] => HTTP/1.1 200 OK
[Server] => nginx
[Date] => Tue, 10 Aug 2021 05:49:20 GMT
[Content-Type] => video/mp4
[Content-Length] => 123596884
[Last-Modified] => Tue, 04 Dec 2018 06:27:23 GMT
[Connection] => close
[ETag] => "5c061e4b-75df054"
[Expires] => Thu, 09 Sep 2021 05:49:20 GMT
[Cache-Control] => max-age=2592000
[Strict-Transport-Security] => max-age=15768000
[Accept-Ranges] => bytes
)
1
耗费时间：0.17363715171814秒
5、如果文件的网址需要 301 跳转，则继续请求 301 跳转的网址，以获取文件的大小。代码实现如下。最终获取到跳转后的文件的真实大小。如图4
PHP
<?php
function remote_filesize($url) {
echo 0 . "\n";
// 返回一个数组，包含有服务器响应一个 HTTP 请求所发送的标头。
$filesize = 0;
$headers = get_headers($url, 1);
if ($headers !== false) {
echo 1 . "\n";
if (!isset($headers['Location']) && isset($headers['Content-Length'])) {
echo 2 . "\n";
$filesize = $headers['Content-Length'];
}
if (isset($headers['Location'])) {
echo 3 . "\n";
return remote_filesize($headers['Location']);
}
}
return $filesize;
}
$startTime = microtime(true);
$url = 'https://media.shuijingwanwq.com/2021/07/ChinaJoy 2015 上海 梦幻西游.mp4';
echo remote_filesize($url) . "\n";
$endTime = microtime(true);
echo '耗费时间：' . ($endTime - $startTime) . '秒';
?>Plaintext
0
1
3
0
1
2
123596884
耗费时间：0.404137134552秒
6、如果文件的网址不需要 301 跳转，执行顺序如下，仅请求了 1 次。同样的文件：秦时明月第一集荧惑守心.mp4，请求的耗费时间相当，不过现方案略微短于之前的方案。注：时间单位为秒。如图5
PHP
<?php
function remote_filesize($url) {
echo 0 . "\n";
// 返回一个数组，包含有服务器响应一个 HTTP 请求所发送的标头。
$filesize = 0;
$headers = get_headers($url, 1);
if ($headers !== false) {
echo 1 . "\n";
if (!isset($headers['Location']) && isset($headers['Content-Length'])) {
echo 2 . "\n";
$filesize = $headers['Content-Length'];
}
if (isset($headers['Location'])) {
echo 3 . "\n";
return remote_filesize($headers['Location']);
}
}
return $filesize;
}
$startTime = microtime(true);
$url = 'https://media.shuijingwanwq.com/2021/07/秦时明月第一集荧惑守心.mp4';
echo remote_filesize($url) . "\n";
$endTime = microtime(true);
echo '耗费时间：' . ($endTime - $startTime) . '秒';
?>
Plaintext
0
1
2
143162935
耗费时间：0.14869999885559秒