棘轮棘轮\ Http \ HttpServer类不存在

I cannot find the Ratchet\Http\HttpServer class. Each time I run the following code it produces an error.

require __DIR__ . '/../vendor/autoload.php';
use Ratchet\Server\IoServer;
use Ratchet\Http\HttpServer;
use Ratchet\WebSocket\WsServer;
use Game\Load;
$server = IoServer::factory(new HttpServer(new WsServer(new Load())), 2000);
$server->run();

Class 'Ratchet\Http\HttpServer' not found