php限制下载速度(php 限速)的实现方法，有需要的朋友可以参考下。
<?php
/**
desc：限制下载速度
link：www.jb200.com
date：2013/2/25
*/
// local file that should be send to the client
$local_file = 'test-file.zip';
// filename that the user gets as default
$download_file = 'your-download-name.zip';
// set the download rate limit (=> 20,5 kb/s)
$download_rate = 20.5;
if(file_exists($local_file) && is_file($local_file)) {
// send headers
header('Cache-control: private');
header('Content-Type: application/octet-stream');
header('Content-Length: '.filesize($local_file));
header('Content-Disposition: filename='.$download_file);
// flush content
flush();
// open file stream
$file = fopen($local_file, "r");
while (!feof($file)) {
// send the current file part to the browser
print fread($file, round($download_rate * 1024));
// flush the content to the browser
flush();
// sleep one second
sleep(1);
}
// close file stream
fclose($file);
}
else {
die('Error: The file '.$local_file.' does not exist!');
}
?>
附：修改Discuz论坛实现对附件下载的限速
研究了一下Discuz的代码，实现了一个可行的方案。
很简单，找到attachment.pnp，找到最下面，有个：
function getlocalfile($filename, $readmod = 1, $range = 0)
修改为：
<?php
function getlocalfile($filename, $readmod = 1, $range = 0) {
if($fp = @fopen($filename, 'rb')) {
@fseek($fp, $range);
$download_rate = 10; //限制网速10kb/s
while(!feof($fp))
{
print fread($fp, round($download_rate * 1024));
flush();
ob_flush();
sleep(1);
}
}
@fclose($fp);
@flush(); @ob_flush();
}
?>
经过测试，发现效果还是很明显的。