说rails文件上传
当前ruby1.9.3 rails 3.2.8，流行的文件上传插件是paperclip和carrierwave

然而，简单的这是需要上传个文件的话，可以用更容易的办法

<%= form_tag({:action => :upload}, :multipart => true) do %>  <%= file_field_tag 'picture' %><% end %> <%= form_for @person do |f| %>  <%= f.file_field :picture %><% end %>def upload  uploaded_io = params[:person][:picture]  File.open(Rails.root.join('public', 'uploads', uploaded_io.original_filename), 'w') do |file|    file.write(uploaded_io.read)  endend