上文说到，由url匹配到app是由journey完成的，那么journey是怎么完成的呢？

首先回到 routes.rb里，get,post 方法最终是会调用match方法的,match方法会调用map_match -> decomposed_match -> ....无数层，最终会调用 journey的routes 的 add_route 方法，生成多个的 Journey::Route 的对象。Journey::Router

ActionDispatch::Routing::RouteSet 作为最后一层rack middleware，在call方法中调用 Journey::Router::Utils.normalize_path将url标准化以使rourney::route可以辨别

  def self.normalize_path(path)
          path ||= ""
          encoding = path.encoding
          path = "/#{path}".dup
          path.squeeze!("/".freeze)
          path.sub!(%r{/+\Z}, "".freeze)
          path.gsub!(/(%[a-f0-9]{2})/) { $1.upcase }
          path = "/".dup if path == "".freeze
          path.force_encoding(encoding)
          path
end

route在app方法中循环调用route.app 的call方法,，依次找到匹配url的app并调用,之后是Routing::RouteSet::Dispatcher.new调用相对应的controller的dispatch方法

def call env
      env['PATH_INFO'] = Utils.normalize_path env['PATH_INFO']

      find_routes(env).each do |match, parameters, route|
        script_name, path_info, set_params = env.values_at('SCRIPT_NAME',
                                                           'PATH_INFO',
                                                           @params_key)

        unless route.path.anchored
          env['SCRIPT_NAME'] = (script_name.to_s + match.to_s).chomp('/')
          env['PATH_INFO']   = match.post_match
        end

        env[@params_key] = (set_params || {}).merge parameters

        status, headers, body = route.app.call(env)

        if 'pass' == headers['X-Cascade']
          env['SCRIPT_NAME'] = script_name
          env['PATH_INFO']   = path_info
          env[@params_key]   = set_params
          next
        end

        return [status, headers, body]
      end

      return [404, {'X-Cascade' => 'pass'}, ['Not Found']]
    end

至此，完成路由