laravel 獲得url 參數

<?php

namespace App\Http\Controllers;

use App\Article;
use Carbon\Carbon;
use App\Http\Requests\Request;
use Illuminate\Support\Facades\DB;

class ArticleController extends Controller
{
      public function demo(Request $request)
    {
//        return $request->all();
        return $request->input("aa");
    }



}

控制器方法 參數 Request