thinkphp框架下404页面设置 仅三步

<?php
namespace HomeController;
use ThinkController;
class EmptyController extends Controller{
  
　　//空操作_empty()方法
  function _empty(){
    header("HTTP/1.0 404 Not Found");
    $this -> display("Public:404");
  }
  
  function index(){
    header("HTTP/1.0 404 Not Found");
    $this -> dislay("Public:404");
  }
}
?>

<?php
namespace HomeController;
use ThinkController;
class PublicController extends Controller{
  function _empty(){
    header("Location:/bbs/thinkphp/404.html");
  }
}
?> 

<?php
namespace HomeController;
// use ThinkController;
class IndexController extends PublicController {
  public function index(){
  
    
    
    
     }
}
？>