命名空间错误。卡在“MyApp\聊天”中

Ratchet中的获取错误简单示例:

Fatal error: Uncaught Error: Class 'MyApp\Chat' not found

我的文件结构如下:

root\composer.json 
root\bin\chat-server.php 
root\src\MyApp\Chat.php

{
    "autoload": {
        "psr-0": {
            "MyApp": "src"
        }
    },
    "require": {
        "cboden/ratchet": "0.3.*"
    }
}

聊天服务器。php是

<?php
use Ratchet\Server\IoServer;
use MyApp\Chat;

    require dirname(__DIR__) . '/vendor/autoload.php';

    $server = IoServer::factory(
        new Chat(),
        8080
    );

    $server->run();

<?php
namespace MyApp;
use Ratchet\MessageComponentInterface;
use Ratchet\ConnectionInterface;

class Chat implements MessageComponentInterface {
    public function onOpen(ConnectionInterface $conn) {
    }

    public function onMessage(ConnectionInterface $from, $msg) {
    }

    public function onClose(ConnectionInterface $conn) {
    }

    public function onError(ConnectionInterface $conn, \Exception $e) {
    }
}

我试过以下方法,但现在仍然有效: PHP Fatal error: Class 'MyApp\Chat' not found in /MyApp/chat-server.php