使用 HTTPRange 支持发送文件(部分下载)
<?php
function smartReadFile($location, $filename, $mimeType='application/octet-stream')
{ if(!file_exists($location))
{ header ("HTTP/1.0 404 Not Found");
return;
}
$size=filesize($location);
$time=date('r',filemtime($location));
$fm=@fopen($location,'rb');
if(!$fm)
{ header ("HTTP/1.0 505 Internal server error");
return;
}
$begin=0;
$end=$size;
if(isset($_SERVER['HTTP_RANGE']))
{ if(preg_match('/bytes=\h*(\d+)-(\d*)[\D.*]?/i', $_SERVER['HTTP_RANGE'], $matches))
{ $begin=intval($matches[0]);
if(!empty($matches[1]))
$end=intval($matches[1]);
}
}
if($begin>0||$end<$size)
header('HTTP/1.0 206 Partial Content');
else
header('HTTP/1.0 200 OK');
header("Content-Type: $mimeType");
header('Cache-Control: public, must-revalidate, max-age=0');
header('Pragma: no-cache');
header('Accept-Ranges: bytes');
header('Content-Length:'.($end-$begin));
header("Content-Range: bytes $begin-$end/$size");
header("Content-Disposition: inline; filename=$filename");
header("Content-Transfer-Encoding: binary\n");
header("Last-Modified: $time");
header('Connection: close');
$cur=$begin;
fseek($fm,$begin,0);
while(!feof($fm)&&$cur<$end&&(connection_status()==0))
{ print fread($fm,min(1024*16,$end-$cur));
$cur+=1024*16;
}
}
?>
用法
<?php
smartReadFile("/tmp/filename","myfile.mp3","audio/mpeg")
?>
对于大型文件,使用 fread 读取可能会很慢,但这是在严格边界内读取文件的唯一方法。你可以修改此代码并添加 fpassthru 而不是 fread 和 while,但这会从开头发送所有数据——如果请求是来自 100mb 文件的第 100 到 200 字节,则这将没有意义。