我看过很多关于类似问题的帖子...都不管用。
1/我安装了带有composer的软件包。

composer require barryvdh/laravel-dompdf

2/已创建应用程序/Http/控制器/PdfController. php

namespace App\Http\Controllers;
 
 use PDF;
 use Illuminate\Http\Request;
 
 class PdfController extends Controller
 {
     public function index() 
     {
         $pdf = PDF::loadView('pdf.sample', [
             'title' => 'CodeAndDeploy.com Laravel Pdf Tutorial',
             'description' => 'This is an example Laravel pdf tutorial.',
             'footer' => 'by <a href="https://codeanddeploy.com">codeanddeploy.com</a>'
         ]);
 
         return $pdf->download('sample.pdf');
     }
 }

3/在web.php中添加了路由（语法对我的其他路由也有效）

// pdf
 //Route::get('/pdf', [PdfController::class, 'index']); (originally)
 Route::get('/pdf', 'App\Http\Controllers\PdfController@index')->name('pdf');

4/尽可能清洁

php artisan cache:clear
 php artisan optimize
 php artisan route:clear

5/如果我运行xxx/pdf或php工匠路由：列表，我得到错误

Target class [App\Http\Controllers\PdfController] does not exist.