PHP闭包的路由实例模型

<?php/* 回调函数 */class App {    protected $routes = [];    protected $responseStatus = '200 OK';    protected $responseContentType = 'text/html';    protected $responseBody = 'Hello World';    public function addRoute($routePath, $routeCallback) {        // 将路由的回调绑定到当前的应用对象上        $this->routes[$routePath] = $routeCallback->bindTo($this, __CLASS__);     }    public function dispatch($currentPath) {        foreach ($this->routes as $routePath => $callback) {            if ($currentPath == $routePath) {                $callback();            }        }        header('HTTP/1.1' . $this->responseStatus);        header('Content-type: '.$this->responseContentType);        header('Content-length: '.mb_strlen($this->responseBody));        echo $this->responseBody;    }}$app = new App();$app->addRoute('/users/josh', function() {    // 在回调函数的上下文环境已经切换到app的实例    $this->responseContentType = 'application/json;charset=utf8';    $this->responseBody = '{"name": "yanming"}';});$app->dispatch('/users/josh');