这些会帮助你……

应用程序控制器

class ApplicationController < ActionController::Base
  protect_from_forgery
  unless Rails.application.config.consider_all_requests_local             
    rescue_from ActionController::RoutingError, ActionController::UnknownController, ::AbstractController::ActionNotFound, ActiveRecord::RecordNotFound, with: lambda { |exception| render_error 404, exception }
  end

  private
    def render_error(status, exception)
      Rails.logger.error status.to_s + " " + exception.message.to_s
      Rails.logger.error exception.backtrace.join("\n") 
      respond_to do |format|
        format.html { render template: "errors/error_#{status}",status: status }
        format.all { render nothing: true, status: status }
      end
    end
end

错误的控制器

class ErrorsController < ApplicationController
  def error_404
    @not_found_path = params[:not_found]
  end
end

视图/错误/error_404.html.haml

.site
  .services-page 
    .error-template
      %h1
        Oops!
      %h2
        404 Not Found
      .error-details
        Sorry, an error has occured, Requested page not found!
        You tried to access '#{@not_found_path}', which is not a valid page.
      .error-actions
        %a.button_simple_orange.btn.btn-primary.btn-lg{href: root_path}
          %span.glyphicon.glyphicon-home
          Take Me Home

<%= render file: 'public/404', status: 404, formats: [:html] %>

只需将此添加到要呈现到404错误页面的页面，就完成了。

所选的答案在Rails 3.1+中不工作，因为错误处理程序被移动到中间件(见github问题)。

这是我找到的解决方案，我很满意。

控制器:

  unless Rails.application.config.consider_all_requests_local
    rescue_from Exception, with: :handle_exception
  end

  def not_found
    raise ActionController::RoutingError.new('Not Found')
  end

  def handle_exception(exception=nil)
    if exception
      logger = Logger.new(STDOUT)
      logger.debug "Exception Message: #{exception.message} \n"
      logger.debug "Exception Class: #{exception.class} \n"
      logger.debug "Exception Backtrace: \n"
      logger.debug exception.backtrace.join("\n")
      if [ActionController::RoutingError, ActionController::UnknownController, ActionController::UnknownAction].include?(exception.class)
        return render_404
      else
        return render_500
      end
    end
  end

  def render_404
    respond_to do |format|
      format.html { render template: 'errors/not_found', layout: 'layouts/application', status: 404 }
      format.all { render nothing: true, status: 404 }
    end
  end

  def render_500
    respond_to do |format|
      format.html { render template: 'errors/internal_server_error', layout: 'layouts/application', status: 500 }
      format.all { render nothing: true, status: 500}
    end
  end

在application.rb:

config.after_initialize do |app|
  app.routes.append{ match '*a', :to => 'application#not_found' } unless config.consider_all_requests_local
end

在我的资源(显示，编辑，更新，删除):

@resource = Resource.find(params[:id]) or not_found

这当然可以改进，但至少，我对not_found和internal_error有不同的视图，而不重写核心Rails函数。

由Steven Soroka提交的新选答案很接近，但不完整。测试本身隐藏了这样一个事实:这并不是返回一个真正的404，而是返回一个状态为200的“success”。原来的答案更接近，但试图呈现的布局，好像没有发生失败。这可以解决所有问题:

render :text => 'Not Found', :status => '404'

下面是我的一个典型的测试集，使用RSpec和Shoulda匹配器，我希望返回404:

describe "user view" do
  before do
    get :show, :id => 'nonsense'
  end

  it { should_not assign_to :user }

  it { should respond_with :not_found }
  it { should respond_with_content_type :html }

  it { should_not render_template :show }
  it { should_not render_with_layout }

  it { should_not set_the_flash }
end

我检查了所有这些元素:赋值变量、响应代码、响应内容类型、模板渲染、布局渲染、flash消息。

我将跳过严格的html应用程序的内容类型检查……有时。毕竟，“怀疑论者会检查所有的抽屉”:)

http://dilbert.com/strips/comic/1998-01-20/

仅供参考:我不建议测试控制器中发生的事情，即“should_raise”。你关心的是输出。上面的测试允许我尝试各种解决方案，无论解决方案是否引发异常、特殊呈现等，测试都保持不变。

这些会帮助你……

应用程序控制器

class ApplicationController < ActionController::Base
  protect_from_forgery
  unless Rails.application.config.consider_all_requests_local             
    rescue_from ActionController::RoutingError, ActionController::UnknownController, ::AbstractController::ActionNotFound, ActiveRecord::RecordNotFound, with: lambda { |exception| render_error 404, exception }
  end

  private
    def render_error(status, exception)
      Rails.logger.error status.to_s + " " + exception.message.to_s
      Rails.logger.error exception.backtrace.join("\n") 
      respond_to do |format|
        format.html { render template: "errors/error_#{status}",status: status }
        format.all { render nothing: true, status: status }
      end
    end
end

错误的控制器

class ErrorsController < ApplicationController
  def error_404
    @not_found_path = params[:not_found]
  end
end

视图/错误/error_404.html.haml

.site
  .services-page 
    .error-template
      %h1
        Oops!
      %h2
        404 Not Found
      .error-details
        Sorry, an error has occured, Requested page not found!
        You tried to access '#{@not_found_path}', which is not a valid page.
      .error-actions
        %a.button_simple_orange.btn.btn-primary.btn-lg{href: root_path}
          %span.glyphicon.glyphicon-home
          Take Me Home

我想对任何不是管理员的登录用户抛出一个“正常的”404，所以我最终在Rails 5中写了这样的东西:

class AdminController < ApplicationController
  before_action :blackhole_admin

  private

  def blackhole_admin
    return if current_user.admin?

    raise ActionController::RoutingError, 'Not Found'
  rescue ActionController::RoutingError
    render file: "#{Rails.root}/public/404", layout: false, status: :not_found
  end
end