Laravel 5.4前后台分离,通过不同的二级域名访问方

<?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 $homeNamespace = 'App\Http\Controllers\Home';//PC端
 protected $adminNamespace = 'App\Http\Controllers\Admin';//管理后台

 /**
 * 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.admin_url') == $sld_prefix){
  $this->mapAdminRoutes();
 }elseif(config('route.home_url') == $sld_prefix){
  $this->mapHomeRoutes();
 }elseif(config('route.api_url') == $sld_prefix){
  $this->mapApiRoutes();
 }
 }

 /**
 * 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'));
 }

 /**
 * Define the "api" routes for the application.
 *
 * These routes are typically stateless.
 *
 * @return void
 */
 protected function mapApiRoutes()
 {
 Route::prefix('api')
  ->middleware('api')
  ->namespace($this->namespace)
  ->group(base_path('routes/api.php'));
 }

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

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

<?php
namespace App\Http\Controllers\Admin;
use App\Http\Controllers\Controller;

class AdminController extends Controller
{
 public function index()
 {
 echo "this is admin";
 }
}