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php - PHP中有部分文件下载的好实现吗?

转载 作者:行者123 更新时间:2023-12-03 00:11:26 27 4
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我正在编写一个允许用户下载文件的 PHP 脚本。基本上,这个想法是防止文件被下载超过 X 次,因为它是付费内容,并且链接不应该传播。

由于文件很大,所以最好实现断点续传。我读过the standard ,但它相当长并且允许一定的灵 active 。由于我需要快速完成它,因此我更喜欢此功能的稳定且经过测试的实现。

有人可以指点我这样的脚本吗?

最佳答案

看来我自己找到了我需要的东西。为了让其他人可以从中受益,链接如下: http://www.coneural.org/florian/papers/04_byteserving.php

以防万一原始页面停止工作(脚本已经很旧了),这里是它的副本:

<?php 
/*

The following byte serving code is (C) 2004 Razvan Florian. You may find the latest version at
http://www.coneural.org/florian/papers/04_byteserving.php

*/
function set_range($range, $filesize, &$first, &$last){
/*
Sets the first and last bytes of a range, given a range expressed as a string
and the size of the file.

If the end of the range is not specified, or the end of the range is greater
than the length of the file, $last is set as the end of the file.

If the begining of the range is not specified, the meaning of the value after
the dash is "get the last n bytes of the file".

If $first is greater than $last, the range is not satisfiable, and we should
return a response with a status of 416 (Requested range not satisfiable).

Examples:
$range='0-499', $filesize=1000 => $first=0, $last=499 .
$range='500-', $filesize=1000 => $first=500, $last=999 .
$range='500-1200', $filesize=1000 => $first=500, $last=999 .
$range='-200', $filesize=1000 => $first=800, $last=999 .

*/
$dash=strpos($range,'-');
$first=trim(substr($range,0,$dash));
$last=trim(substr($range,$dash+1));
if ($first=='') {
//suffix byte range: gets last n bytes
$suffix=$last;
$last=$filesize-1;
$first=$filesize-$suffix;
if($first<0) $first=0;
} else {
if ($last=='' || $last>$filesize-1) $last=$filesize-1;
}
if($first>$last){
//unsatisfiable range
header("Status: 416 Requested range not satisfiable");
header("Content-Range: */$filesize");
exit;
}
}

function buffered_read($file, $bytes, $buffer_size=1024){
/*
Outputs up to $bytes from the file $file to standard output, $buffer_size bytes at a time.
*/
$bytes_left=$bytes;
while($bytes_left>0 && !feof($file)){
if($bytes_left>$buffer_size)
$bytes_to_read=$buffer_size;
else
$bytes_to_read=$bytes_left;
$bytes_left-=$bytes_to_read;
$contents=fread($file, $bytes_to_read);
echo $contents;
flush();
}
}

function byteserve($filename){
/*
Byteserves the file $filename.

When there is a request for a single range, the content is transmitted
with a Content-Range header, and a Content-Length header showing the number
of bytes actually transferred.

When there is a request for multiple ranges, these are transmitted as a
multipart message. The multipart media type used for this purpose is
"multipart/byteranges".
*/

$filesize=filesize($filename);
$file=fopen($filename,"rb");

$ranges=NULL;
if ($_SERVER['REQUEST_METHOD']=='GET' && isset($_SERVER['HTTP_RANGE']) && $range=stristr(trim($_SERVER['HTTP_RANGE']),'bytes=')){
$range=substr($range,6);
$boundary='g45d64df96bmdf4sdgh45hf5';//set a random boundary
$ranges=explode(',',$range);
}

if($ranges && count($ranges)){
header("HTTP/1.1 206 Partial content");
header("Accept-Ranges: bytes");
if(count($ranges)>1){
/*
More than one range is requested.
*/

//compute content length
$content_length=0;
foreach ($ranges as $range){
set_range($range, $filesize, $first, $last);
$content_length+=strlen("\r\n--$boundary\r\n");
$content_length+=strlen("Content-type: application/pdf\r\n");
$content_length+=strlen("Content-range: bytes $first-$last/$filesize\r\n\r\n");
$content_length+=$last-$first+1;
}
$content_length+=strlen("\r\n--$boundary--\r\n");

//output headers
header("Content-Length: $content_length");
//see http://httpd.apache.org/docs/misc/known_client_problems.html for an discussion of x-byteranges vs. byteranges
header("Content-Type: multipart/x-byteranges; boundary=$boundary");

//output the content
foreach ($ranges as $range){
set_range($range, $filesize, $first, $last);
echo "\r\n--$boundary\r\n";
echo "Content-type: application/pdf\r\n";
echo "Content-range: bytes $first-$last/$filesize\r\n\r\n";
fseek($file,$first);
buffered_read ($file, $last-$first+1);
}
echo "\r\n--$boundary--\r\n";
} else {
/*
A single range is requested.
*/
$range=$ranges[0];
set_range($range, $filesize, $first, $last);
header("Content-Length: ".($last-$first+1) );
header("Content-Range: bytes $first-$last/$filesize");
header("Content-Type: application/pdf");
fseek($file,$first);
buffered_read($file, $last-$first+1);
}
} else{
//no byteserving
header("Accept-Ranges: bytes");
header("Content-Length: $filesize");
header("Content-Type: application/pdf");
readfile($filename);
}
fclose($file);
}

function serve($filename, $download=0){
//Just serves the file without byteserving
//if $download=true, then the save file dialog appears
$filesize=filesize($filename);
header("Content-Length: $filesize");
header("Content-Type: application/pdf");
$filename_parts=pathinfo($filename);
if($download) header('Content-disposition: attachment; filename='.$filename_parts['basename']);
readfile($filename);
}

//unset magic quotes; otherwise, file contents will be modified
set_magic_quotes_runtime(0);

//do not send cache limiter header
ini_set('session.cache_limiter','none');


$filename='myfile.pdf'; //this is the PDF file that will be byteserved
byteserve($filename); //byteserve it!
?>

关于php - PHP中有部分文件下载的好实现吗?,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/1395656/

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