在实行前后台分离时，使用artisan时出现Undefined index: HTTP_HOST

<?php

namespace App\Providers;

use Illuminate\Support\Facades\Route;
use Illuminate\Foundation\Support\Providers\RouteServiceProvider as ServiceProvider;

class RouteServiceProvider extends ServiceProvider
{
/**
     * This namespace is applied to your controller routes.
     *
     * In addition, it is set as the URL generator's root namespace.
     *
     * @var string
     */
    //protected $namespace = 'App\Http\Controllers';

protected $authorNamespace = 'App\Http\Controllers\Author';

protected $homeNamespace = 'App\Http\Controllers\Home';

protected $apiNamespace = 'App\Http\Controllers\Api';

/**
     * Define your route model bindings, pattern filters, etc.
     *
     * @return void
     */
public function boot()
    {
//

parent::boot();
    }

/**
     * Define the routes for the application.
     *
     * @return void
     */
public function map()
    {
//$this->mapApiRoutes();

       //$this->mapWebRoutes();


$sld_prefix = explode('.',$_SERVER['HTTP_HOST'])[0];
if(config('route.api_url') == $sld_prefix){
$this->mapApiRoutes();
        }elseif(config('route.author_url') == $sld_prefix){
$this->mapAuthorRoutes();
        }elseif(config('route.home_url') == $sld_prefix){
$this->mapHomeRoutes();
       }

    }

/**
     * Define the "web" routes for the application.
     *
     * These routes all receive session state, CSRF protection, etc.
     *
     * @return void
     */
protected function mapWebRoutes()
    {
        Route::middleware('web')
             ->namespace($this->namespace)
             ->group(base_path('routes/web.php'));
    }


/**
     * 管理后台
     */
protected function mapApiRoutes()
    {
        Route::middleware('web')
            ->namespace($this->apiNamespace)
            ->group(base_path('routes/api.php'));
    }

/**
     * 管理作者
     */
protected function mapAuthorRoutes()
    {
        Route::middleware('web')
            ->namespace($this->authorNamespace)
            ->group(base_path('routes/author.php'));
    }

/**
     * 管理前台
     */
protected function mapHomeRoutes()
    {
        Route::middleware('web')
            ->namespace($this->homeNamespace)
            ->group(base_path('routes/home.php'));
    }

}