ruby4.1.8 catch class error

一个迭代开发中的网站难免存在bug，出bug的时候客户体验就很不好了，为解决此问题，可以在class error产生的时候，触发跳转到统一提示页面，并给开发人员发邮件报错误信息，提高测试能力和用户体验。以下是核心方法；在ApplicationController中添加如下代码，不同rails版本的class error略有变化。

AR_ERROR_CLASSES = [ActiveRecord::RecordNotFound, ActiveRecord::StatementInvalid]
  ERROR_CLASSES = [NameError, NoMethodError, RuntimeError,
         ActionView::TemplateError,
         ActiveRecord::StaleObjectError, ActionController::RoutingError,
         ActionController::UnknownController, AbstractController::ActionNotFound,
         ActionController::MethodNotAllowed, ActionController::InvalidAuthenticityToken]

  ACCESS_DENIED_CLASSES = [CanCan::AccessDenied]

  if Rails.env.production?
    rescue_from *AR_ERROR_CLASSES, :with => :render_ar_error
    rescue_from *ERROR_CLASSES, :with => :render_error
    rescue_from *ACCESS_DENIED_CLASSES, :with => :render_access_denied
  end
  
  #called by last route matching unmatched routes.  Raises RoutingError which will be rescued from in the same way as other exceptions.

#备注rails3.1后ActionController::RoutingError在routes.rb中最后加如下代码才能catch了。
#rails3下：match '*unmatched_route', :to => 'application#raise_not_found!'
#rails4下：get '*unmatched_route', :to => 'application#raise_not_found!'

  def raise_not_found!
    raise ActionController::RoutingError.new("No route matches #{params[:unmatched_route]}")
  end

  def render_ar_error(exception)
    case exception
    when *AR_ERROR_CLASSES then exception_class = exception.class.to_s
    else exception_class = 'Exception'
    end

    send_error_email(exception, exception_class)
  end

  def render_error(exception)
    case exception
    when *ERROR_CLASSES then exception_class = exception.class.to_s
    else exception_class = 'Exception'
    end

    send_error_email(exception, exception_class)
  end

  def render_access_denied(exception)
    case exception
    when *ACCESS_DENIED_CLASSES then exception_class = exception.class.to_s
    else exception_class = "Exception"
    end

    send_error_email(exception, exception_class)
  end