php实现文件安全下载

public function downloads($name){
$name_tmp = explode("_",$name);
$type = $name_tmp[0];
$file_time = explode(".",$name_tmp[3]);
$file_time = $file_time[0];
$file_date = date("Y/md",$file_time);
$file_dir = SITE_PATH."/data/uploads/$type/$file_date/";

if(!file_exists($file_dir.$name)){
header("Content-type: text/html; charset=utf-8");
echo "File not found!";
exit;
}else{
$file = fopen($file_dir.$name,"r");
Header("Content-type: application/octet-stream");
Header("Accept-Ranges: bytes");
Header("Accept-Length: ".filesize($file_dir . $name));
Header("Content-Disposition: attachment; filename=".$name);
echo fread($file, filesize($file_dir.$name));
fclose($file);
}
}

摘自：http://zlf140.blog.163.com/blog/static/1406592201310253543723/