学习yii2.0框架阅读代码(二十)

   /**
     * 新建一个控制器实例基于给定的路线.
     *
     * 路线应该是相对于这个模块。该方法实现了以下算法
     * to resolve the given route:
     *
     * 1. If the route is empty, use [[defaultRoute]];
     * 2. If the first segment of the route is a valid module ID as declared in [[modules]],
     *    call the module‘s `createController()` with the rest part of the route;
     * 3. If the first segment of the route is found in [[controllerMap]], create a controller
     *    based on the corresponding configuration found in [[controllerMap]];
     * 4. The given route is in the format of `abc/def/xyz`. Try either `abc\DefController`
     *    or `abc\def\XyzController` class within the [[controllerNamespace|controller namespace]].
     *
     * If any of the above steps resolves into a controller, it is returned together with the rest
     * part of the route which will be treated as the action ID. Otherwise, false will be returned.
     *
     * @param string $route the route consisting of module, controller and action IDs.
     * @return array|boolean If the controller is created successfully, it will be returned together
     * with the requested action ID. Otherwise false will be returned.
     * @throws InvalidConfigException if the controller class and its file do not match.
     */
    public function createController($route)
    {
        if ($route === ‘‘) {
            $route = $this->defaultRoute;
        }

        // double slashes or leading/ending slashes may cause substr problem
        // 如果有双斜线或者结束的斜线，可能会引起问题
        $route = trim($route, ‘/‘);
        if (strpos($route, ‘//‘) !== false) {
            return false;
        }

        if (strpos($route, ‘/‘) !== false) {
            // 如果存在斜线，就根据斜线分割route，并限制最多分割成两个
            list ($id, $route) = explode(‘/‘, $route, 2);
        } else {
            // 不存在，就直接赋值给$id
            $id = $route;
            $route = ‘‘;
        }

        // module and controller map take precedence
        if (isset($this->controllerMap[$id])) {
            // 如果controllerMap中存在相应的$id，就使用Yii::createObject去创建该controller的实例
            $controller = Yii::createObject($this->controllerMap[$id], [$id, $this]);
            return [$controller, $route];
        }
        // 根据id获取module
        $module = $this->getModule($id);
        if ($module !== null) {
            // 获取到module，就递归调用相应module的createController去创建controller的实例
            return $module->createController($route);
        }

        // 如果取到了module，就需要继续去取controller的ID
        // 再次根据斜线分割
        if (($pos = strrpos($route, ‘/‘)) !== false) {
            // 如果有斜线，就将module的ID和后面截取出的内容一起拼成ID
            $id .= ‘/‘ . substr($route, 0, $pos);
            // 剩余的赋给route
            $route = substr($route, $pos + 1);
        }

        // 然后根据ID去创建controller的实例
        $controller = $this->createControllerByID($id);
        // 未创建成功，并且route不为空
        if ($controller === null && $route !== ‘‘) {
            // 将route拼接到ID中，再次去创建controller出的实例
            $controller = $this->createControllerByID($id . ‘/‘ . $route);
            $route = ‘‘;
        }

        return $controller === null ? false : [$controller, $route];
    }