php实现文件下载！

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);
		}
	}