我们正在使用 PHP 脚本来隧道文件下载，因为我们不想暴露可下载文件的绝对路径：
header("Content-Type: $ctype");
header("Content-Length: " . filesize($file));
header("Content-Disposition: attachment; filename=\"$fileName\"");
readfile($file);
很遗憾，我们注意到最终用户无法恢复通过此脚本进行的下载。
有没有办法通过这种基于 PHP 的解决方案来支持可恢复下载？
【问题讨论】：
标签： php download resume-download
您需要做的第一件事是在所有响应中发送Accept-Ranges: bytes 标头，告诉客户端您支持部分内容。然后，如果收到带有Range: bytes=x-y 标头的请求（x 和y 是数字），您解析客户端请求的范围，照常打开文件，提前查找x 字节并发送下一个@ 987654328@ - x 字节。还将响应设置为HTTP/1.0 206 Partial Content。
无需测试任何东西，这或多或少都可以工作：
$filesize = filesize($file);
$offset = 0;
$length = $filesize;
if ( isset($_SERVER['HTTP_RANGE']) ) {
// if the HTTP_RANGE header is set we're dealing with partial content
$partialContent = true;
// find the requested range
// this might be too simplistic, apparently the client can request
// multiple ranges, which can become pretty complex, so ignore it for now
preg_match('/bytes=(\d+)-(\d+)?/', $_SERVER['HTTP_RANGE'], $matches);
$offset = intval($matches[1]);
$length = intval($matches[2]) - $offset;
} else {
$partialContent = false;
}
$file = fopen($file, 'r');
// seek to the requested offset, this is 0 if it's not a partial content request
fseek($file, $offset);
$data = fread($file, $length);
fclose($file);
if ( $partialContent ) {
// output the right headers for partial content
header('HTTP/1.1 206 Partial Content');
header('Content-Range: bytes ' . $offset . '-' . ($offset + $length) . '/' . $filesize);
}
// output the regular HTTP headers
header('Content-Type: ' . $ctype);
header('Content-Length: ' . $filesize);
header('Content-Disposition: attachment; filename="' . $fileName . '"');
header('Accept-Ranges: bytes');
// don't forget to send the data too
print($data);
我可能遗漏了一些明显的东西，而且我肯定忽略了一些潜在的错误来源，但这应该是一个开始。
有一个description of partial content here，我在fread 的文档页面上找到了一些关于部分内容的信息。
【讨论】：
$length 将是否定的。 $length = (($matches[2]) ? intval($matches[2]) : $filesize) - $offset; 解决了这个问题。 2.Content-Range将第一个字节视为0，所以最后一个字节为$filesize - 1。因此，它必须是($offset + $length - 1)。
编辑 2017/01 - 我写了一个库来用 PHP >=7.0 https://github.com/DaveRandom/Resume
编辑 2016/02 - 代码完全重写为一组模块化工具作为示例用法，而不是单一功能。已合并以下 cmets 中提到的更正。
一个经过测试的、有效的解决方案（很大程度上基于上面 Theo 的回答），它在一组几个独立的工具中处理可恢复的下载。此代码需要 PHP 5.4 或更高版本。
这个解决方案仍然只能处理每个请求一个范围，但在任何情况下使用我能想到的标准浏览器，这应该不会造成问题。
<?php
/**
* Get the value of a header in the current request context
*
* @param string $name Name of the header
* @return string|null Returns null when the header was not sent or cannot be retrieved
*/
function get_request_header($name)
{
$name = strtoupper($name);
// IIS/Some Apache versions and configurations
if (isset($_SERVER['HTTP_' . $name])) {
return trim($_SERVER['HTTP_' . $name]);
}
// Various other SAPIs
foreach (apache_request_headers() as $header_name => $value) {
if (strtoupper($header_name) === $name) {
return trim($value);
}
}
return null;
}
class NonExistentFileException extends \RuntimeException {}
class UnreadableFileException extends \RuntimeException {}
class UnsatisfiableRangeException extends \RuntimeException {}
class InvalidRangeHeaderException extends \RuntimeException {}
class RangeHeader
{
/**
* The first byte in the file to send (0-indexed), a null value indicates the last
* $end bytes
*
* @var int|null
*/
private $firstByte;
/**
* The last byte in the file to send (0-indexed), a null value indicates $start to
* EOF
*
* @var int|null
*/
private $lastByte;
/**
* Create a new instance from a Range header string
*
* @param string $header
* @return RangeHeader
*/
public static function createFromHeaderString($header)
{
if ($header === null) {
return null;
}
if (!preg_match('/^\s*(\S+)\s*(\d*)\s*-\s*(\d*)\s*(?:,|$)/', $header, $info)) {
throw new InvalidRangeHeaderException('Invalid header format');
} else if (strtolower($info[1]) !== 'bytes') {
throw new InvalidRangeHeaderException('Unknown range unit: ' . $info[1]);
}
return new self(
$info[2] === '' ? null : $info[2],
$info[3] === '' ? null : $info[3]
);
}
/**
* @param int|null $firstByte
* @param int|null $lastByte
* @throws InvalidRangeHeaderException
*/
public function __construct($firstByte, $lastByte)
{
$this->firstByte = $firstByte === null ? $firstByte : (int)$firstByte;
$this->lastByte = $lastByte === null ? $lastByte : (int)$lastByte;
if ($this->firstByte === null && $this->lastByte === null) {
throw new InvalidRangeHeaderException(
'Both start and end position specifiers empty'
);
} else if ($this->firstByte < 0 || $this->lastByte < 0) {
throw new InvalidRangeHeaderException(
'Position specifiers cannot be negative'
);
} else if ($this->lastByte !== null && $this->lastByte < $this->firstByte) {
throw new InvalidRangeHeaderException(
'Last byte cannot be less than first byte'
);
}
}
/**
* Get the start position when this range is applied to a file of the specified size
*
* @param int $fileSize
* @return int
* @throws UnsatisfiableRangeException
*/
public function getStartPosition($fileSize)
{
$size = (int)$fileSize;
if ($this->firstByte === null) {
return ($size - 1) - $this->lastByte;
}
if ($size <= $this->firstByte) {
throw new UnsatisfiableRangeException(
'Start position is after the end of the file'
);
}
return $this->firstByte;
}
/**
* Get the end position when this range is applied to a file of the specified size
*
* @param int $fileSize
* @return int
* @throws UnsatisfiableRangeException
*/
public function getEndPosition($fileSize)
{
$size = (int)$fileSize;
if ($this->lastByte === null) {
return $size - 1;
}
if ($size <= $this->lastByte) {
throw new UnsatisfiableRangeException(
'End position is after the end of the file'
);
}
return $this->lastByte;
}
/**
* Get the length when this range is applied to a file of the specified size
*
* @param int $fileSize
* @return int
* @throws UnsatisfiableRangeException
*/
public function getLength($fileSize)
{
$size = (int)$fileSize;
return $this->getEndPosition($size) - $this->getStartPosition($size) + 1;
}
/**
* Get a Content-Range header corresponding to this Range and the specified file
* size
*
* @param int $fileSize
* @return string
*/
public function getContentRangeHeader($fileSize)
{
return 'bytes ' . $this->getStartPosition($fileSize) . '-'
. $this->getEndPosition($fileSize) . '/' . $fileSize;
}
}
class PartialFileServlet
{
/**
* The range header on which the data transmission will be based
*
* @var RangeHeader|null
*/
private $range;
/**
* @param RangeHeader $range Range header on which the transmission will be based
*/
public function __construct(RangeHeader $range = null)
{
$this->range = $range;
}
/**
* Send part of the data in a seekable stream resource to the output buffer
*
* @param resource $fp Stream resource to read data from
* @param int $start Position in the stream to start reading
* @param int $length Number of bytes to read
* @param int $chunkSize Maximum bytes to read from the file in a single operation
*/
private function sendDataRange($fp, $start, $length, $chunkSize = 8192)
{
if ($start > 0) {
fseek($fp, $start, SEEK_SET);
}
while ($length) {
$read = ($length > $chunkSize) ? $chunkSize : $length;
$length -= $read;
echo fread($fp, $read);
}
}
/**
* Send the headers that are included regardless of whether a range was requested
*
* @param string $fileName
* @param int $contentLength
* @param string $contentType
*/
private function sendDownloadHeaders($fileName, $contentLength, $contentType)
{
header('Content-Type: ' . $contentType);
header('Content-Length: ' . $contentLength);
header('Content-Disposition: attachment; filename="' . $fileName . '"');
header('Accept-Ranges: bytes');
}
/**
* Send data from a file based on the current Range header
*
* @param string $path Local file system path to serve
* @param string $contentType MIME type of the data stream
*/
public function sendFile($path, $contentType = 'application/octet-stream')
{
// Make sure the file exists and is a file, otherwise we are wasting our time
$localPath = realpath($path);
if ($localPath === false || !is_file($localPath)) {
throw new NonExistentFileException(
$path . ' does not exist or is not a file'
);
}
// Make sure we can open the file for reading
if (!$fp = fopen($localPath, 'r')) {
throw new UnreadableFileException(
'Failed to open ' . $localPath . ' for reading'
);
}
$fileSize = filesize($localPath);
if ($this->range == null) {
// No range requested, just send the whole file
header('HTTP/1.1 200 OK');
$this->sendDownloadHeaders(basename($localPath), $fileSize, $contentType);
fpassthru($fp);
} else {
// Send the request range
header('HTTP/1.1 206 Partial Content');
header('Content-Range: ' . $this->range->getContentRangeHeader($fileSize));
$this->sendDownloadHeaders(
basename($localPath),
$this->range->getLength($fileSize),
$contentType
);
$this->sendDataRange(
$fp,
$this->range->getStartPosition($fileSize),
$this->range->getLength($fileSize)
);
}
fclose($fp);
}
}
示例用法：
<?php
$path = '/local/path/to/file.ext';
$contentType = 'application/octet-stream';
// Avoid sending unexpected errors to the client - we should be serving a file,
// we don't want to corrupt the data we send
ini_set('display_errors', '0');
try {
$rangeHeader = RangeHeader::createFromHeaderString(get_request_header('Range'));
(new PartialFileServlet($rangeHeader))->sendFile($path, $contentType);
} catch (InvalidRangeHeaderException $e) {
header("HTTP/1.1 400 Bad Request");
} catch (UnsatisfiableRangeException $e) {
header("HTTP/1.1 416 Range Not Satisfiable");
} catch (NonExistentFileException $e) {
header("HTTP/1.1 404 Not Found");
} catch (UnreadableFileException $e) {
header("HTTP/1.1 500 Internal Server Error");
}
// It's usually a good idea to explicitly exit after sending a file to avoid sending any
// extra data on the end that might corrupt the file
exit;
【讨论】：
$start = $end - intval($range[0]); 应该是 range[1]
是的。支持字节范围。见RFC 2616 section 14.35。
这基本上意味着您应该读取Range 标头，并从指定的偏移量开始提供文件。
这意味着您不能使用 readfile()，因为它服务于整个文件。而是先使用fopen()，然后fseek() 到正确的位置，然后使用fpassthru() 提供文件。
【讨论】：
echo file_get_contents(...) 不起作用（OOM）。所以我不认为这是一个问题。 PHP 5.3。
fpassthru 的“弱”配置（字面意思是：共享主机）上，即使是 50 MB 文件也会失败。如果您在弱服务器配置上提供大文件，则绝对不应该使用它。正如@Wimmer 正确指出的那样，fread + print 就是你在这种情况下所需要的。
这工作 100% 超级检查它 我正在使用它，没有问题了。
/* Function: download with resume/speed/stream options */
/* List of File Types */
function fileTypes($extension){
$fileTypes['swf'] = 'application/x-shockwave-flash';
$fileTypes['pdf'] = 'application/pdf';
$fileTypes['exe'] = 'application/octet-stream';
$fileTypes['zip'] = 'application/zip';
$fileTypes['doc'] = 'application/msword';
$fileTypes['xls'] = 'application/vnd.ms-excel';
$fileTypes['ppt'] = 'application/vnd.ms-powerpoint';
$fileTypes['gif'] = 'image/gif';
$fileTypes['png'] = 'image/png';
$fileTypes['jpeg'] = 'image/jpg';
$fileTypes['jpg'] = 'image/jpg';
$fileTypes['rar'] = 'application/rar';
$fileTypes['ra'] = 'audio/x-pn-realaudio';
$fileTypes['ram'] = 'audio/x-pn-realaudio';
$fileTypes['ogg'] = 'audio/x-pn-realaudio';
$fileTypes['wav'] = 'video/x-msvideo';
$fileTypes['wmv'] = 'video/x-msvideo';
$fileTypes['avi'] = 'video/x-msvideo';
$fileTypes['asf'] = 'video/x-msvideo';
$fileTypes['divx'] = 'video/x-msvideo';
$fileTypes['mp3'] = 'audio/mpeg';
$fileTypes['mp4'] = 'audio/mpeg';
$fileTypes['mpeg'] = 'video/mpeg';
$fileTypes['mpg'] = 'video/mpeg';
$fileTypes['mpe'] = 'video/mpeg';
$fileTypes['mov'] = 'video/quicktime';
$fileTypes['swf'] = 'video/quicktime';
$fileTypes['3gp'] = 'video/quicktime';
$fileTypes['m4a'] = 'video/quicktime';
$fileTypes['aac'] = 'video/quicktime';
$fileTypes['m3u'] = 'video/quicktime';
return $fileTypes[$extention];
};
/*
Parameters: downloadFile(File Location, File Name,
max speed, is streaming
If streaming - videos will show as videos, images as images
instead of download prompt
*/
function downloadFile($fileLocation, $fileName, $maxSpeed = 100, $doStream = false) {
if (connection_status() != 0)
return(false);
// in some old versions this can be pereferable to get extention
// $extension = strtolower(end(explode('.', $fileName)));
$extension = pathinfo($fileName, PATHINFO_EXTENSION);
$contentType = fileTypes($extension);
header("Cache-Control: public");
header("Content-Transfer-Encoding: binary\n");
header('Content-Type: $contentType');
$contentDisposition = 'attachment';
if ($doStream == true) {
/* extensions to stream */
$array_listen = array('mp3', 'm3u', 'm4a', 'mid', 'ogg', 'ra', 'ram', 'wm',
'wav', 'wma', 'aac', '3gp', 'avi', 'mov', 'mp4', 'mpeg', 'mpg', 'swf', 'wmv', 'divx', 'asf');
if (in_array($extension, $array_listen)) {
$contentDisposition = 'inline';
}
}
if (strstr($_SERVER['HTTP_USER_AGENT'], "MSIE")) {
$fileName = preg_replace('/\./', '%2e', $fileName, substr_count($fileName, '.') - 1);
header("Content-Disposition: $contentDisposition;
filename=\"$fileName\"");
} else {
header("Content-Disposition: $contentDisposition;
filename=\"$fileName\"");
}
header("Accept-Ranges: bytes");
$range = 0;
$size = filesize($fileLocation);
if (isset($_SERVER['HTTP_RANGE'])) {
list($a, $range) = explode("=", $_SERVER['HTTP_RANGE']);
str_replace($range, "-", $range);
$size2 = $size - 1;
$new_length = $size - $range;
header("HTTP/1.1 206 Partial Content");
header("Content-Length: $new_length");
header("Content-Range: bytes $range$size2/$size");
} else {
$size2 = $size - 1;
header("Content-Range: bytes 0-$size2/$size");
header("Content-Length: " . $size);
}
if ($size == 0) {
die('Zero byte file! Aborting download');
}
set_magic_quotes_runtime(0);
$fp = fopen("$fileLocation", "rb");
fseek($fp, $range);
while (!feof($fp) and ( connection_status() == 0)) {
set_time_limit(0);
print(fread($fp, 1024 * $maxSpeed));
flush();
ob_flush();
sleep(1);
}
fclose($fp);
return((connection_status() == 0) and ! connection_aborted());
}
/* Implementation */
// downloadFile('path_to_file/1.mp3', '1.mp3', 1024, false);
【讨论】：
MP4，但它会发送一个MP3，但不幸的是Chrome，无法在这个MP3 中寻找。
解决这个问题的一个非常好的方法是使用 mod_xsendfile Apache 模块，而无需“滚动你自己的”PHP 代码。然后在 PHP 中，您只需设置适当的标头。 Apache 开始做自己的事了。
header("X-Sendfile: /path/to/file");
header("Content-Type: application/octet-stream");
header("Content-Disposition: attachment; file=\"filename\"");
【讨论】：
XSendFilePath <absolute path> [AllowFileDelete] (tn123.org/mod_xsendfile/beta)。
如果您愿意安装新的 PECL 模块，使用 PHP 支持可恢复下载的最简单方法是通过http_send_file()，就像这样
<?php
http_send_content_disposition("document.pdf", true);
http_send_content_type("application/pdf");
http_throttle(0.1, 2048);
http_send_file("../report.pdf");
?>
来源：http://www.php.net/manual/en/function.http-send-file.php
我们用它来提供数据库存储的内容，它就像一个魅力！
【讨论】：
是的，您可以为此使用 Range 标头。您需要再向客户端提供 3 个标头才能完整下载：
header ("Accept-Ranges: bytes");
header ("Content-Length: " . $fileSize);
header ("Content-Range: bytes 0-" . $fileSize - 1 . "/" . $fileSize . ";");
对于中断的下载，您需要通过以下方式检查 Range 请求标头：
$headers = getAllHeaders ();
$range = substr ($headers['Range'], '6');
在这种情况下，不要忘记使用 206 状态码提供内容：
header ("HTTP/1.1 206 Partial content");
header ("Accept-Ranges: bytes");
header ("Content-Length: " . $remaining_length);
header ("Content-Range: bytes " . $start . "-" . $to . "/" . $fileSize . ";");
您将从请求标头中获取 $start 和 $to 变量，并使用 fseek() 查找文件中的正确位置。
【讨论】：
最佳答案有各种错误。
bytes a-b 应该表示[a, b] 而不是[a, b)，并且bytes a- 不被处理。这是我修改后的代码：
// TODO: configurations here
$fileName = "File Name";
$file = "File Path";
$bufferSize = 2097152;
$filesize = filesize($file);
$offset = 0;
$length = $filesize;
if (isset($_SERVER['HTTP_RANGE'])) {
// if the HTTP_RANGE header is set we're dealing with partial content
// find the requested range
// this might be too simplistic, apparently the client can request
// multiple ranges, which can become pretty complex, so ignore it for now
preg_match('/bytes=(\d+)-(\d+)?/', $_SERVER['HTTP_RANGE'], $matches);
$offset = intval($matches[1]);
$end = $matches[2] || $matches[2] === '0' ? intval($matches[2]) : $filesize - 1;
$length = $end + 1 - $offset;
// output the right headers for partial content
header('HTTP/1.1 206 Partial Content');
header("Content-Range: bytes $offset-$end/$filesize");
}
// output the regular HTTP headers
header('Content-Type: ' . mime_content_type($file));
header("Content-Length: $filesize");
header("Content-Disposition: attachment; filename=\"$fileName\"");
header('Accept-Ranges: bytes');
$file = fopen($file, 'r');
// seek to the requested offset, this is 0 if it's not a partial content request
fseek($file, $offset);
// don't forget to send the data too
ini_set('memory_limit', '-1');
while ($length >= $bufferSize)
{
print(fread($file, $bufferSize));
$length -= $bufferSize;
}
if ($length) print(fread($file, $length));
fclose($file);
【讨论】：
ini_set('memory_limit', '-1');？
if(!isset($matches[2])) { $end=$fs-1; } else { $end = intval($matches[2]); }
【讨论】：
启用了小型作曲家的类，其工作方式与 pecl http_send_file 相同。这意味着支持可恢复下载和限制。 https://github.com/diversen/http-send-file
【讨论】：
您可以使用以下代码在任何浏览器中支持字节范围请求
<?php
$file = 'YouTube360p.mp4';
$fileLoc = $file;
$filesize = filesize($file);
$offset = 0;
$fileLength = $filesize;
$length = $filesize - 1;
if ( isset($_SERVER['HTTP_RANGE']) ) {
// if the HTTP_RANGE header is set we're dealing with partial content
$partialContent = true;
preg_match('/bytes=(\d+)-(\d+)?/', $_SERVER['HTTP_RANGE'], $matches);
$offset = intval($matches[1]);
$tempLength = intval($matches[2]) - 0;
if($tempLength != 0)
{
$length = $tempLength;
}
$fileLength = ($length - $offset) + 1;
} else {
$partialContent = false;
$offset = $length;
}
$file = fopen($file, 'r');
// seek to the requested offset, this is 0 if it's not a partial content request
fseek($file, $offset);
$data = fread($file, $length);
fclose($file);
if ( $partialContent ) {
// output the right headers for partial content
header('HTTP/1.1 206 Partial Content');
}
// output the regular HTTP headers
header('Content-Type: ' . mime_content_type($fileLoc));
header('Content-Length: ' . $fileLength);
header('Content-Disposition: inline; filename="' . $file . '"');
header('Accept-Ranges: bytes');
header('Content-Range: bytes ' . $offset . '-' . $length . '/' . $filesize);
// don't forget to send the data too
print($data);
?>
【讨论】：
在 HTTP 中恢复下载是通过 Range 标头完成的。如果请求包含Range 标头，并且如果其他指示符（例如If-Match、If-Unmodified-Since）表明自下载开始后内容没有更改，则给出206 响应码（而不是200），在 Content-Range 标头中指明您要返回的字节范围，然后在响应正文中提供该范围。
不过，我不知道如何在 PHP 中做到这一点。
【讨论】：
感谢西奥！你的方法不能直接用于流媒体 divx，因为我发现 divx 播放器发送的范围像 bytes=9932800-
但它向我展示了如何做到这一点，谢谢：D
if(isset($_SERVER['HTTP_RANGE']))
{
file_put_contents('showrange.txt',$_SERVER['HTTP_RANGE']);
【讨论】：
我创建了一个用于提供文件的库，支持条件（除非文件已更改，否则不要再次下载文件）和范围（暂停和恢复下载）请求。它甚至适用于虚拟文件系统，例如Flysystem。
在这里查看：FileWaiter
示例用法：
use Stadly\FileWaiter\Adapter\Local;
use Stadly\FileWaiter\File;
use Stadly\FileWaiter\Waiter;
$streamFactory = new \GuzzleHttp\Psr7\HttpFactory(); // Any PSR-17 compatible stream factory.
$file = new File(new Local('filename.txt', $streamFactory)); // Or another file adapter. See below.
$responseFactory = new \GuzzleHttp\Psr7\HttpFactory(); // Any PSR-17 compatible response factory.
$waiter = new Waiter($file, $responseFactory);
$request = \GuzzleHttp\Psr7\ServerRequest::fromGlobals(); // Any PSR-7 compatible server request.
$response = $waiter->handle($request); // The response is created by the response factory.
$emitter = new \Laminas\HttpHandlerRunner\Emitter\SapiEmitter(); // Any way of emitting PSR-7 responses.
$emitter->emit($response);
die();
【讨论】：