src/Leevel/Router/View.php
public function display(string $file, array $vars = [], ?string $ext = null): string
    {
        return $this->theme->display($file, $vars, $ext, false);
    }
public function display(string $file, array $vars = [], ?string $ext = null): string
    {
        return $this->theme->display($file, $vars, $ext, false);
    }
加载视图文件.

@param string $file
@param array  $vars
@param string $ext

@return string