php控制文件下载速度的方法

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<?php

/*

* set here a limit of downloading rate (e.g. 10.20 Kb/s)

*/

$download_rate = 10.20;

$download_file = 'download-file.zip';

$target_file = 'target-file.zip';

if(file_exists($download_file)){

/* headers */

header('Last-Modified:'.gmdate('D, d M Y H:i:s').'GMT');

header('Cache-control: private');

header('Content-Type: application/octet-stream');

header('Content-Length: '.filesize($download_file));

header('Content-Disposition: filename='.$target_file);

/* flush content */

flush();

/* open file */

$fh = @fopen($download_file, 'r');

while(!feof($fh)){

/* send only current part of the file to browser */

print fread($fh, round($download_rate * 1024));

/* flush the content to the browser */

flush();

/* sleep for 1 sec */

sleep(1);

}

/* close file */

@fclose($fh);

}else{

die('Fatal error: the '.$download_file.' file does not exist!');

}

?>