protected function exportInfo($arr, &$err){

        $nameInfo = array('user_name'=>'vlson','age'=>'18','addrPrvoince'=>'北京');

        $userInfo = $this->mysql->selectRows("select user_name, age, addr_province from user where addr_province like '%北京%');

        $str = "名字,年龄,地区\n";

        foreach($userInfo as $key=>$row){

            $str .= $row['user_name'].",".$row['age'].",".$row['addr_province']."\n"; //用引文逗号分开，\n 可以让其换行

        }

        $filename = $nameInfo['addrPrvoince'].date('Y-m-d').'.csv'; //设置文件名

        $this->export_csv($filename,$str); //导出

    }

　　private function export_csv($filename,$data) {

        header("Content-type:text/csv");

        header("Content-Disposition:attachment;filename=".$filename);

        header('Cache-Control:must-revalidate,post-check=0,pre-check=0');

        header('Expires:0');

        header('Pragma:public');

        echo $data;

        exit();//输出之后退出或者die，否则会将代码写入到文件中

    }