PHP处理大文件下载

<?php
set_time_limit(0);  //大文件在读取内容未结束时会被超时处理，导致下载文件不全。  
  
$fpath = 'book.zip';
$file_pathinfo = pathinfo($fpath);  
$file_name = $file_pathinfo['basename'];  
$file_extension = $file_pathinfo['extension'];  
$handle = fopen($fpath,"rb");  
if (FALSE === $handle)  
    exit("Failed to open the file");  
$filesize = filesize($fpath);  
  
header("Content-type:video/mpeg4");//更具不同的文件类型设置header输出类型  
header("Accept-Ranges:bytes");  
header("Accept-Length:".$filesize);  
header("Content-Disposition: attachment; filename=".$file_name);  
  
$contents = '';  
while (!feof($handle)) {  
    $contents = fread($handle, 8192);  
    echo $contents;  
    @ob_flush();  //把数据从PHP的缓冲中释放出来  
    flush();      //把被释放出来的数据发送到浏览器
}  
fclose($handle);  
exit;