rails2.0為了防范CSRF (Cross-Site Request
Forgery)攻擊,提供了一個(gè)小小的手段,那就是protect_from_forgery
http://api.rubyonrails.org/classes/ActionController/RequestForgeryProtection/ClassMethods.html
http://api.rubyonrails.org/classes/ActionController/RequestForgeryProtection/ClassMethods.html