frontcontroller.php

<?php

/*
 * 先引导系统，然后单例方式实例化本前端控制器类（FC），FC负责解释请求的变量，接管程序的运行，分发路由至用户自定义的类，即动作控制器（AC）
 */
class FrontController {
    private static $_instance = null;
    protected $_controller;
    protected $_action;
    protected $_params = array();

    // 防止直接new
    private function __construct() {

        // parse uri into string
        $request_uri = $_SERVER['REQUEST_URI'];
        $request_str = str_replace(Config::get('application.base_url'), '', $request_uri);

        while(substr($request_str, strlen($request_str)-1) == '/') {
            $request_str = substr($request_str, 0, -1);
        }

        // convert uri into array
        $request_str_arr = explode('/', $request_str);
        unset($request_uri);
        unset($request_str);

        // first two segments is controller/action
        $this->_controller = empty($request_str_arr['0']) ? Config::get('application.default_controller') : $request_str_arr['0'];
        $this->_action     = empty($request_str_arr['1']) ?  Config::get('application.default_action') : $request_str_arr['1'];

        // uri parameters
        for($i = 2; $i < count($request_str_arr); $i++)
        {
            $f = $i%2;
            if($f == 0) $this->_params[$request_str_arr[$i]] = empty($request_str_arr[$i + 1]) ? null : $request_str_arr[$i + 1];
        }

        Log::info('Initialized FC successfully');
    }

    // 防止直接clone
    private function __clone() {}

    public static function getInstance() {
        if(!(self::$_instance instanceof self)) {
            self::$_instance = new FrontController();
        }
        return self::$_instance;
    }

    // 根据控制器和方法名称，执行控制器对应的方法
    public function route() {
        $request = new Request();
        $request->url_elements = array();

        // eg. /default/index
        if(isset($_SERVER['PATH_INFO'])) {
          $request->url_elements = explode('/', $_SERVER['PATH_INFO']);
        }

        $request->verb = $_SERVER['REQUEST_METHOD'];

        switch($request->verb)
        {
          case 'GET':
            $controllerName    = ucfirst($this->_controller) . '_Controller';
            $controllerHandler = new $controllerName();

            $action = 'action_'.$this->_action;
            if(!method_exists($controllerHandler, $action)){
                throw new Exception('不存在方法：'.$action);
            }
            $controllerHandler->$action($this->_params);
            exit;
          case 'POST':
          case 'PUT':
            $request->parameters = json_decode(file_get_contents('php://input'), 1);
            break;
          case 'DELETE':
          default:
            $request->parameters = array();
        }

        if($request->url_elements) {
          $controller_name = ucfirst($request->url_elements[1]) . '_Controller';
          if(class_exists($controller_name)) {
            $controller = new $controller_name();
            $action_name = 'rest_' . ucfirst($request->verb);
            $response = $controller->$action_name($request);
          } else {
            header('HTTP/1.0 400 Bad Request');
            $response = "Unknown Request for " . $request->url_elements[1];
          }
        } else {
          header('HTTP/1.0 400 Bad Request');
          $response = "Unknown Request";
        }

        echo json_encode($response);

    }
}