PHP实现HTTP断点续传的方法

<?php
/**
* PHP-HTTP断点续传实现
* @param string $path: 文件所在路径
* @param string $file: 文件名
* @return void
*/
function download($path,$file) {
 $real = $path.'/'.$file;
 if(!file_exists($real)) {
   return false;
 }
 $size = filesize($real);
 $size2 = $size-1;
 $range = 0;
 if(isset($_SERVER['HTTP_RANGE'])) {
   header('HTTP /1.1 206 Partial Content');
   $range = str_replace('=','-',$_SERVER['HTTP_RANGE']);
   $range = explode('-',$range);
   $range = trim($range[1<
ada0
/span>]);
   header('Content-Length:'.$size);
   header('Content-Range: bytes '.$range.'-'.$size2.'/'.$size);
 } else {
   header('Content-Length:'.$size);
   header('Content-Range: bytes 0-'.$size2.'/'.$size);
 }
 header('Accenpt-Ranges: bytes');
 header('application/octet-stream');
 header("Cache-control: public");
 header("Pragma: public");
 //解决在IE中下载时中文乱码问题
 $ua = $_SERVER['HTTP_USER_AGENT'];
 if(preg_match('/MSIE/',$ua)) {
   $ie_filename = str_replace('+','%20',urlencode($file));
   header('Content-Dispositon:attachment; filename='.$ie_filename);
 } else {
   header('Content-Dispositon:attachment; filename='.$file);
 }
 $fp = fopen($real,'rb+');
 fseek($fp,$range);
 while(!feof($fp)) {
   set_time_limit(0);
   print(fread($fp,1024));
   flush();
   ob_flush();
 }
 fclose($fp);
}