请问默认值这个 url 应该如何产生？

创建middleware SetDefaultLocaleForUrls

namespace App\Http\Middleware;

use Closure;
use Illuminate\Support\Facades\URL;

class SetDefaultLocaleForUrls
{
    /**
     * Handle an incoming request.
     *
     * @param  \Illuminate\Http\Request  $request
     * @param  \Closure  $next
     * @return mixed
     */
    public function handle($request, Closure $next)
    {
        URL::defaults(['locale'=>$request->user()->locale]);
        return $next($request);
    }
}

注册middleware

    protected $routeMiddleware = [
        ...
        'locale'=>SetDefaultLocaleForUrls::class
    ];

注册路由

Route::get('/posts',function() {
    return route('users.show', ['user'=>1]);
})->middleware('locale');

产生url

并不像想象的那样是 http://la57.study/en/users/1 请问应该怎么用？谢谢。