http://blog.csdn.net/abbuggy/article/details/7516224

在《Ruby on Rails，服务端如何响应页面提交的请求》中我们知道，页面提交给web服务器的请求先是尝试直接查找并返回public目录中的资源，如果没有找到则将请求交给Rails的Routes。Routes根据路由配置，将请求转化为对Controller中的Action并调用之。Routes的配置可说的细节很多，最开始我们先关注三种最简单的方式：Simple route,Default route,Root route。Routes的配置信息存放在config/routes.rb文件当中。

当前我的routes.rb文件如下所示，大段被注释掉的内容是各种配置用法的举例先不用理会，其中第二行get "demo/index"这句就是在《Ruby on Rails，创建最简单的视图/控制器单元Hello World》中通过调用生成视图/控制器命令被自动添加过来的。这就是一个Simple route。

在Routes配置文件中，越靠上的一行配置拥有越高的优先级。

SimpleSite::Application.routes.draw do
  get "demo/index"

  # The priority is based upon order of creation:
  # first created -> highest priority.

  # Sample of regular route:
  #   match 'products/:id' => 'catalog#view'
  # Keep in mind you can assign values other than :controller and :action

  # Sample of named route:
  #   match 'products/:id/purchase' => 'catalog#purchase', :as => :purchase
  # This route can be invoked with purchase_url(:id => product.id)

  # Sample resource route (maps HTTP verbs to controller actions automatically):
  #   resources :products

  # Sample resource route with options:
  #   resources :products do
  #     member do
  #       get 'short'
  #       post 'toggle'
  #     end
  #
  #     collection do
  #       get 'sold'
  #     end
  #   end

  # Sample resource route with sub-resources:
  #   resources :products do
  #     resources :comments, :sales
  #     resource :seller
  #   end

  # Sample resource route with more complex sub-resources
  #   resources :products do
  #     resources :comments
  #     resources :sales do
  #       get 'recent', :on => :collection
  #     end
  #   end

  # Sample resource route within a namespace:
  #   namespace :admin do
  #     # Directs /admin/products/* to Admin::ProductsController
  #     # (app/controllers/admin/products_controller.rb)
  #     resources :products
  #   end

  # You can have the root of your site routed with "root"
  # just remember to delete public/index.html.
  # root :to => 'welcome#index'

  # See how all your routes lay out with "rake routes"

  # This is a legacy wild controller route that's not recommended for RESTful applications.
  # Note: This route will make all actions in every controller accessible via GET requests.
  # match ':controller(/:action(/:id))(.:format)'
end

match "demo/index", :to => "demo#index"

这种路由配置最简单易懂但是比较不易于维护，因为我们要在每次增加视图/控制器时维护Routes配置。我们想使用一个更加通用的规则，在这个规则的帮助下我们修改视图/控制器规则后依然能够工作-Default route。

get /:controller/:action/:id的意思是调用名为demo的Controller中名为index的Action并传入id值。

match ':controller(/:action(/:id(.:format)))'

SimpleSite::Application.routes.draw do
  match ':controller(/:action(/:id))(.:format)'
end

修改了routes.rb之后需要重启服务器。请求“localhost:3000/demo/index”依然能够转向之前的页面，说明Default route配置包含了之前Simple route的情况。

由于我们之前删除了public目录中的index.html，所以当以“localhost:3000/”请求时将没有规则能够匹配“/”。

这时，我们需要配置Root route。

root :to => "demo#index"

SimpleSite::Application.routes.draw do
  root :to => "demo#index"  
  match ':controller(/:action(/:id))(.:format)'
end

重启服务器后访问“localhost:3000/”得到了配置中规定的页面。

http://blog.csdn.net/abbuggy/article/details/7516224