PianoTime/app/Exports/StudentsExport.php

<?php
namespace App\Exports;

use App\Models\Student;
use Illuminate\Support\Facades\Log;
use Maatwebsite\Excel\Concerns\FromCollection;
use Maatwebsite\Excel\Concerns\WithHeadings;
use Maatwebsite\Excel\Concerns\WithEvents;
use Maatwebsite\Excel\Events\AfterSheet;

class StudentsExport implements FromCollection, WithHeadings, WithEvents
{

    public $columns = 7;

    public function collection()
    {
        $students = Student::orderBy('created_at', 'desc')->get();

        $items = collect();
        foreach($students as $item) {
            $tmp = $item->getCourseInfo();

            $item = collect([
                'name' => $item->name,
                'phone' => $item->phone,
                'course_name' => $tmp['course_name'],
                'apply_date' => $tmp['apply_date'],
                'end_date' => $tmp['end_date'],
                'teacher_names' => $tmp['teacher_names'],
                'remark' => $item->remark,
            ]);

            $items->push($item);
        }

        return $items;
    }

    public function headings(): array
    {
        return [
            '姓名',
            '手机号',
            '课程名称',
            '报名日期',
            '截止日期',
            '任课老师',
            '备注',
        ];
    }

    public function registerEvents(): array
    {
        return [
            AfterSheet::class => function(AfterSheet $event) {
                $sheet = $event->sheet->getDelegate();
                for($i = 0; $i <= $this->columns; ++$i) {
                    $sheet->getColumnDimensionByColumn($i)->setWidth(14);
                }
                $items = $sheet->getHighestRowAndColumn();
                $sheet->getStyle('A1:' . $items['column'] . $items['row'])->getAlignment()->setHorizontal('center');
            },
        ];
    }
}