尝试使用通常的 PHP 强制下载文件：
header("Content-type: $type" );
header("Content-Disposition: attachment; filename=$name");
header('Content-Length: ' . filesize($path));
对于小于 32 mb 的文件，它可以成功执行。对于更大的文件，它只返回归零的文件。
显然存在某种限制，但是是什么设定了它呢？使用 Apache 2.2.11 和 PHP 5.3.0。
我最终偶然发现了这篇文章：http://w-shadow.com/blog/2007/08/12/how-to-force-file-download-with-php/。
function output_file($file, $name, $mime_type='')
{
/*
This function takes a path to a file to output ($file),
the filename that the browser will see ($name) and
the MIME type of the file ($mime_type, optional).
If you want to do something on download abort/finish,
register_shutdown_function('function_name');
*/
if(!is_readable($file)) die('File not found or inaccessible!');
$size = filesize($file);
$name = rawurldecode($name);
/* Figure out the MIME type (if not specified) */
$known_mime_types=array(
"pdf" => "application/pdf",
"txt" => "text/plain",
"html" => "text/html",
"htm" => "text/html",
"exe" => "application/octet-stream",
"zip" => "application/zip",
"doc" => "application/msword",
"xls" => "application/vnd.ms-excel",
"ppt" => "application/vnd.ms-powerpoint",
"gif" => "image/gif",
"png" => "image/png",
"jpeg"=> "image/jpg",
"jpg" => "image/jpg",
"php" => "text/plain"
);
if($mime_type==''){
$file_extension = strtolower(substr(strrchr($file,"."),1));
if(array_key_exists($file_extension, $known_mime_types)){
$mime_type=$known_mime_types[$file_extension];
} else {
$mime_type="application/force-download";
};
};
ob_end_clean(); //turn off output buffering to decrease cpu usage
// required for IE, otherwise Content-Disposition may be ignored
if(ini_get('zlib.output_compression'))
ini_set('zlib.output_compression', 'Off');
header('Content-Type: ' . $mime_type);
header('Content-Disposition: attachment; filename="'.$name.'"');
header("Content-Transfer-Encoding: binary");
header('Accept-Ranges: bytes');
/* The three lines below basically make the
download non-cacheable */
header("Cache-control: private");
header('Pragma: private');
header("Expires: Mon, 26 Jul 1997 05:00:00 GMT");
// multipart-download and download resuming support
if(isset($_SERVER['HTTP_RANGE']))
{
list($a, $range) = explode("=",$_SERVER['HTTP_RANGE'],2);
list($range) = explode(",",$range,2);
list($range, $range_end) = explode("-", $range);
$range=intval($range);
if(!$range_end) {
$range_end=$size-1;
} else {
$range_end=intval($range_end);
}
$new_length = $range_end-$range+1;
header("HTTP/1.1 206 Partial Content");
header("Content-Length: $new_length");
header("Content-Range: bytes $range-$range_end/$size");
} else {
$new_length=$size;
header("Content-Length: ".$size);
}
/* output the file itself */
$chunksize = 1*(1024*1024); //you may want to change this
$bytes_send = 0;
if ($file = fopen($file, 'r'))
{
if(isset($_SERVER['HTTP_RANGE']))
fseek($file, $range);
while(!feof($file) &&
(!connection_aborted()) &&
($bytes_send<$new_length)
)
{
$buffer = fread($file, $chunksize);
print($buffer); //echo($buffer); // is also possible
flush();
$bytes_send += strlen($buffer);
}
fclose($file);
} else die('Error - can not open file.');
die();
}
/*********************************************
Example of use
**********************************************/
/*
Make sure script execution doesn't time out.
Set maximum execution time in seconds (0 means no limit).
*/
set_time_limit(0);
$file_path='that_one_file.txt';
output_file($file_path, 'some file.txt', 'text/plain');
添加所有推荐的标题并使用：
ob_end_clean(); //turn off output buffering to decrease cpu usage
在任何输出之前 - 有帮助。没有更多可观察到的限制。文件下载完全，即使是大文件。
看起来您正在将整个文件加载到 RAM 中，然后再将其发送给收件人。您需要研究 PHP Streams，以便能够发送完整的文件内容，而不必先将其全部读入 RAM：http://php.net/streams
也可能需要
set_time_limit(0);在 php.ini 中您将看到该设置。
我记不起选项名称了，但我现在会查看我的 php.ini 并尝试找到它。
只需将其删除即可工作。
好吧，如果我错了，请有人纠正我，但是是吗
内存限制
Apache 中的构建有 1 GB 限制，即使您尝试从根目录下载文件，也完全避免了 php。
我花了很长时间去调试。我认为这可能是 CloudFlare 背后的代理，标头丢失。结果我正在流式传输的文件达到了内存限制。
我做到了
ini_set('memory_limit', '128M');
缺少已接受的答案
ob_start();此外，该网站上的重复评分使我无法对实际帖子发表评论（废话）