远程文件大小,无需下载文件 [英] Remote file size without downloading file
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问题描述
有没有一种方法可以获取远程文件 http://my_url/my_file.txt 的大小而无需正在下载文件?
Is there a way to get the size of a remote file http://my_url/my_file.txt without downloading the file?
推荐答案
找到了有关此这里:
这是(我发现)获得遥控器大小的最佳方法 文件.请注意,HEAD请求不会获得请求的实际内容, 他们只是检索标题.因此向资源发出HEAD请求 100MB将花费与HEAD请求相同的时间 1KB的资源.
Here's the best way (that I've found) to get the size of a remote file. Note that HEAD requests don't get the actual body of the request, they just retrieve the headers. So making a HEAD request to a resource that is 100MB will take the same amount of time as a HEAD request to a resource that is 1KB.
<?php
/**
* Returns the size of a file without downloading it, or -1 if the file
* size could not be determined.
*
* @param $url - The location of the remote file to download. Cannot
* be null or empty.
*
* @return The size of the file referenced by $url, or -1 if the size
* could not be determined.
*/
function curl_get_file_size( $url ) {
// Assume failure.
$result = -1;
$curl = curl_init( $url );
// Issue a HEAD request and follow any redirects.
curl_setopt( $curl, CURLOPT_NOBODY, true );
curl_setopt( $curl, CURLOPT_HEADER, true );
curl_setopt( $curl, CURLOPT_RETURNTRANSFER, true );
curl_setopt( $curl, CURLOPT_FOLLOWLOCATION, true );
curl_setopt( $curl, CURLOPT_USERAGENT, get_user_agent_string() );
$data = curl_exec( $curl );
curl_close( $curl );
if( $data ) {
$content_length = "unknown";
$status = "unknown";
if( preg_match( "/^HTTP\/1\.[01] (\d\d\d)/", $data, $matches ) ) {
$status = (int)$matches[1];
}
if( preg_match( "/Content-Length: (\d+)/", $data, $matches ) ) {
$content_length = (int)$matches[1];
}
// http://en.wikipedia.org/wiki/List_of_HTTP_status_codes
if( $status == 200 || ($status > 300 && $status <= 308) ) {
$result = $content_length;
}
}
return $result;
}
?>
用法:
$file_size = curl_get_file_size( "http://stackoverflow.com/questions/2602612/php-remote-file-size-without-downloading-file" );
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