PHP实现下载功能类

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); 
} 
}