rails用户认证

反正自己也是新手，生怕学来的东西给忘了……
ruby1.9.3-p194 rails3.2.8
rails new authen --skip-bundle
cd authen
rails g model user name:string salt:string hashed_pswd:string
rake db:migrate
编辑app/models/user.rb

class User < ActiveRecord::Base
  attr_accessor :password, :pswd_confirmation
  attr_accessible :password, :name
  validates_presence_of :name
  validates_uniqueness_of :name
  before_create :generate_hashed

  def self.authentication(name, ps)
    user = User.find_by_name(name)
    return user if user && user.hashed_pswd == Digest::SHA256.hexdigest(user.salt + ps)
  end
  private
  def generate_hashed    
    self.salt = Array.new(10){ rand(1024).to_s(36) }.join
    self.hashed_pswd = Digest::SHA256.hexdigest(self.salt + @password)
  end
end

rails g controller sessions
编辑app/controllers/sessions_controller.rb

# encoding: utf-8
class SessionsController < ApplicationController
  def new
  end

  def create
    @user = User.authentication(params[:name], params[:password])
    if @user
      session[:user_id] = @user.id
      flash[:notice] = "热烈欢迎#{@user.name}莅临"
      #root_path为主页路径
      redirect_to root_path
    else
      flash[:notice] = "The username or password is not correct!!!"
      redirect_to new_session_path
    end
  end 

  def logout
    session[:user_id] = nil
    flash[:notice] = "你已经退出登录"
    redirect_to new_session_path
  end
end

编辑app/controllers/application_controller.rb，添加

  def current_user
    if session[:user_id]
      cur_user = User.find(session[:user_id])
      return cur_user
    end
  end

创建app/views/sessions/new.html.erb

<h2>Sign in</h2>
<%= form_tag :sessions do  %>
<p>
<%= label :name, "登录名："  %>
<%= text_field_tag :name, params[:name]  %>
</p>
<p>
<%= label :password, "密码： "  %>
<%= password_field_tag :password, params[:password]  %>
</p>
<%= submit_tag "登录" %>
<% end %>

在主页相关的controller中index方法（或者等价的方法中）添加：

@current_user = current_user

在主页中适当位置添加

<% if @current_user %>
  <p>当前用户是：<%= @current_user.name  %></p>
  <%= link_to "Logout", logout_path %>
<% end %>

编辑config/routes.rb
添加：

match '/logout' => 'sessions#logout', :as => "logout"
resources :sessions

rails s
浏览器进入http://localhost:3000/sessions/new进行登录


最后，在实际运用中最好还是使用成熟的gem，比如devise，否则还要自己实现一些其他功能。