public function downloadFile(){
	$M = M($this->tableName);
	$map['id'] = I('fileId');
	$info = $M->where($map)->find();
	$filepath = '.'.$info['path'];
	if(!file_exists($filepath)){
		echo '文件不存在！';
		exit;
	}

	$file = fopen($filepath,"r"); // 打开文件
	// 输入文件标签
	Header("Content-type: application/octet-stream");
	Header("Accept-Ranges: bytes");
	Header("Accept-Length: ".filesize($filepath));
	Header("Content-Disposition: attachment; filename=" . $info['savename']);
	// 输出文件内容
	echo fread($file,filesize($filepath));
	fclose($file);
	exit;
}