一个测试用的文件下载的类-powered by widuu

学习文件下载，我们下载的时候mime类型非常不好判断 所以我写的类就直接加进去了，扩展性非常强，如果您有什么建议或者需要什么功能我会以后添加，当然初步测试用，

<?php
/*
 *文件下载类 powered by widuu
 *测试用 wdphp框架开发 作者肖伟
 */
class download{
		private $filename;
		function __construct($filename){
			$this->filename=$filename;
		}
		function download(){
			header("Content-Type:".$this->mime($this->filename));
			header('Content-Disposition: attachment; filename='.$this->filename);
			header('Content-Length:'.filesize($this->filename));
			readfile($this->filename); 
		}
		private function mime($filename){
				$mime=array(
					'txt' => 'text/plain',
					'htm' => 'text/html',
					'html' => 'text/html',
					'php' => 'text/html',
					'css' => 'text/css',
					'js' => 'application/javascript',
					'json' => 'application/json',
					'xml' => 'application/xml',
					'swf' => 'application/x-shockwave-flash',
					'flv' => 'video/x-flv',

					// images
					'png' => 'image/png',
					'jpe' => 'image/jpeg',
					'jpeg' => 'image/jpeg',
					'jpg' => 'image/jpeg',
					'gif' => 'image/gif',
					'bmp' => 'image/bmp',
					'ico' => 'image/vnd.microsoft.icon',
					'tiff' => 'image/tiff',
					'tif' => 'image/tiff',
					'svg' => 'image/svg+xml',
					'svgz' => 'image/svg+xml',
					);
					$file=explode('.',$this->filename);
					if($dir=in_array($file[1],array_keys($mime))){
						return $mime[$file[1]];
					}else{
						die("不是允许下载的类型");
					}
}
}
/*测试用
$download=new download("cache.txt");
$download->download();
*/
?>