在不使用Composer的Codeigniter中使用PhpSpreadsheet

<?php
require_once APPPATH . 'libraries/PhpSpreadsheet/src/Bootstrap.php';
use PhpOffice\PhpSpreadsheet\Spreadsheet;
use PhpOffice\PhpSpreadsheet\Writer\Xlsx;

class Spreadsheet {
    private $spreadsheet;

    public function __construct() {
        $this->spreadsheet = new Spreadsheet();
    }

    // 添加其他自定义函数和方法

    public function exportExcel($data, $filename) {
        // 导出Excel的代码
        // 可以参考PhpSpreadsheet的官方文档（https://phpspreadsheet.readthedocs.io/en/latest/）来编写导出Excel的代码
    }
}

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

class ExampleController extends CI_Controller {
    public function __construct() {
        parent::__construct();
        $this->load->library('spreadsheet');
    }

    public function export() {
        $data = array(
            // Excel数据
        );

        $filename = 'example.xlsx';
        $this->spreadsheet->exportExcel($data, $filename);
    }
}