src/Controller.php
public function url(string $controller = null, string $action = null, array $params = []): string
    {
        if (!$controller) {
            $controller = $this->controller;
        }
        return Router::encode($this->module, $controller, $action, $params);
    }
public function url(string $controller = null, string $action = null, array $params = []): string
    {
        if (!$controller) {
            $controller = $this->controller;
        }
        return Router::encode($this->module, $controller, $action, $params);
    }
构造URL,提供一个Controller的默认值
@param string $controller
@param string $action
@param array $params
@return string