php文件下载（可限制下载速度）实现代码

作者：袖梨 2022-06-24

*/
$file = "test.mp3"; // file to be send to the client
$speed = 8.5; // 8,5 kb/s download rate limit
if(file_exists($file) && is_file($file)) {
   header("cache-control: private");
   header("content-type: application/octet-stream");
   header("content-length: ".filesize($file));
   header("content-disposition: filename=$file" . "%20");
   flush();
   $fd = fopen($file, "r");
    while(!feof($fd)) {
          echo fread($fd, round($speed*1024));
       flush();
       sleep(1);
    }
   fclose ($fd);
}

/*
flush
flush函数刷新php程序的缓冲实现echo动态输出
本函数实现的结果是页面不断地显示echo输出　的数据
for ($i=10; $i>0; $i--)
{
echo $i.'
';
ob_flush();
flush();
sleep(1);
}
ob_end_flush();