엑셀출력을 위한 Test.php 컨트롤러 중 객체 생성부분

<?

defined('BASEPATH') OR exit('No direct script access allowed');

use PhpOffice\PhpSpreadsheet\Spreadsheet;

use PhpOffice\PhpSpreadsheet\Writer\Xlsx;

class Test extends CI_Controller {

    public function index()

    {

$this->load->library("Excelsheet");

        $spreadsheet = new Excelsheet();

-------------------------------------------------------

라이브러리 (libraries)의 Excelsheet.php 부분

<?php if ( ! defined('BASEPATH')) exit('No direct script access allowed');

require_once APPPATH."/third_party/PhpOffice/PhpSpreadsheet/Spreadsheet.php";

class Excelsheet extends Spreadsheet{    public function __construct(){        parent::__construct();    }}

// 더 위 소스가 더 안 붙여지네요 ;;; 

--------------------------------------------

Third-party부분에 required한 디렉토리와 소스들 및 해당 Spreadsheet.php ..

<?php

namespace PhpOffice\PhpSpreadsheet;

use PhpOffice\PhpSpreadsheet\Calculation\Calculation;use PhpOffice\PhpSpreadsheet\Style\Style;use PhpOffice\PhpSpreadsheet\Worksheet\Iterator;use PhpOffice\PhpSpreadsheet\Worksheet\Worksheet;

class Spreadsheet{

이렇게 되있는데요 아래외 같은 오류가 납니다. 아마 네임스페이스와 관련있는거 같은데 디렉토리구조는 맞는데

왜 오류가 날까요?

Fatal error: Class 'Spreadsheet' not found in /home/webstormdev/malangmalang/admin/application/libraries/Excelsheet.php on line 5

A PHP Error was encountered

Severity: Error

Message: Class 'Spreadsheet' not found

Filename: libraries/Excelsheet.php

Line Number: 5

Backtrace: