php限制下载速度的实现方法

3. /**

4. desc：限制下载速度
5. link：bbs.it-home.org
6. date：2013/2/25
7. */
8. // local file that should be send to the client
9. $local_file = 'test-file.zip';

10. // filename that the user gets as default

11. $download_file = 'your-download-name.zip';

12. // set the download rate limit (=> 20,5 kb/s)

13. $download_rate = 20.5;

14. if(file_exists($local_file) && is_file($local_file)) {

15. // send headers
16. header('Cache-control: private');
17. header('Content-Type: application/octet-stream');
18. header('Content-Length: '.filesize($local_file));
19. header('Content-Disposition: filename='.$download_file);

20. // flush content

21. flush();

22. // open file stream

23. $file = fopen($local_file, "r");
24. while (!feof($file)) {
25. // send the current file part to the browser
26. print fread($file, round($download_rate * 1024));
27. // flush the content to the browser
28. flush();
29. // sleep one second
30. sleep(1);
31. }
32. // close file stream
33. fclose($file);
34. }
35. else {
36. die('Error: The file '.$local_file.' does not exist!');
37. }
38. ?>

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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：

3. function getlocalfile($filename, $readmod = 1, $range = 0) {

4. if($fp = @fopen($filename, 'rb')) {
5. @fseek($fp, $range);
6. $download_rate = 10; //限制网速10kb/s
7. while(!feof($fp))
8. {
9. print fread($fp, round($download_rate * 1024));
10. flush();
11. ob_flush();
12. sleep(1);
13. }
14. }
15. @fclose($fp);

16. @flush(); @ob_flush();

17. }
18. ?>

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经过测试，发现效果还是很明显的。