rails4 rack调用

module Rails
  class Server < ::Rack::Server
    def default_options
      super.merge({
        Port:               3000,
        DoNotReverseLookup: true,
        environment:        (ENV['RAILS_ENV'] || ENV['RACK_ENV'] || "development").dup,
        daemonize:          false,
        debugger:           false,
        pid:                File.expand_path("tmp/pids/server.pid"),
        config:             File.expand_path("config.ru")
      })
    end

    def start
      print_boot_information
      trap(:INT) { exit }
      create_tmp_directories
      log_to_stdout if options[:log_stdout]

      super
    ensure
      # The '-h' option calls exit before @options is set.
      # If we call 'options' with it unset, we get double help banners.
      puts 'Exiting' unless @options && options[:daemonize]
    end
  end
end

可以看到和rails2相比，已经大不一样了，代码全部移动到了Rails模块中，结构也更加清晰