我的route.rb文件中有：
namespace :admin do
resources :products, :brands, :categories, :effects
end
rake routes后，生成的路由如下：
Prefix Verb URI Pattern Controller#Action
root GET / page#index
products GET /products(.:format) products#index
product GET /products/:id(.:format) products#show
brands GET /brands(.:format) brands#index
categories GET /categories(.:format) categories#index
effects GET /effects(.:format) effects#index
admin_products GET /admin/products(.:format) admin/products#index
POST /admin/products(.:format) admin/products#create
new_admin_product GET /admin/products/new(.:format) admin/products#new
edit_admin_product GET /admin/products/:id/edit(.:format) admin/products#edit
admin_product GET /admin/products/:id(.:format) admin/products#show
PATCH /admin/products/:id(.:format) admin/products#update
PUT /admin/products/:id(.:format) admin/products#update
DELETE /admin/products/:id(.:format) admin/products#destroy
admin_brands GET /admin/brands(.:format) admin/brands#index
POST /admin/brands(.:format) admin/brands#create
new_admin_brand GET /admin/brands/new(.:format) admin/brands#new
edit_admin_brand GET /admin/brands/:id/edit(.:format) admin/brands#edit
admin_brand GET /admin/brands/:id(.:format) admin/brands#show
PATCH /admin/brands/:id(.:format) admin/brands#update
PUT /admin/brands/:id(.:format) admin/brands#update
DELETE /admin/brands/:id(.:format) admin/brands#destroy
admin_categories GET /admin/categories(.:format) admin/categories#index
POST /admin/categories(.:format) admin/categories#create
new_admin_category GET /admin/categories/new(.:format) admin/categories#new
edit_admin_category GET /admin/categories/:id/edit(.:format) admin/categories#edit
admin_category GET /admin/categories/:id(.:format) admin/categories#show
PATCH /admin/categories/:id(.:format) admin/categories#update
PUT /admin/categories/:id(.:format) admin/categories#update
DELETE /admin/categories/:id(.:format) admin/categories#destroy
admin_effects GET /admin/effects(.:format) admin/effects#index
POST /admin/effects(.:format) admin/effects#create
new_admin_effect GET /admin/effects/new(.:format) admin/effects#new
edit_admin_effect GET /admin/effects/:id/edit(.:format) admin/effects#edit
admin_effect GET /admin/effects/:id(.:format) admin/effects#show
PATCH /admin/effects/:id(.:format) admin/effects#update
PUT /admin/effects/:id(.:format) admin/effects#update
DELETE /admin/effects/:id(.:format) admin/effects#destroy
admin GET /admin(.:format) admin#index
我想知道，类似admin/brands#new这样的控制器和动作，应该怎么生成？
如楼主所说，其实是这样的：
controller里面有一个文件夹，叫做“admin”，这个文件夹里面有一些文件：
products_controller.rb
brands_controller.rb
等等
参考这个： http://guides.ruby-china.org/routing.html#%E6%8E%A7%E5%88%B6%E5%99%A8%...
app/controllers/admin/brands_controller.rb
class Admin::BrandsController < ApplicationController
...
routes.rb
namespace :admin do
resources :brands
end
楼上正解，另外可以试试
shgenerate scaffold admin::blog
参见Rails Guide