#重写登陆成功后的跳转页面。
  def after_sign_in_path_for(resource)
    stored_location_for(resource) || root_path
  end

  #登出之后的跳转页面。
  def after_sign_out_path_for(resource_or_scope)
    backstage_sign_in_path
  end

  def configure_permitted_parameters
    devise_parameter_sanitizer.for(:sign_in) { |u| u.permit(:username, :password, :remember_me) }
  end