新增：系统消息接口

app/controllers/api/v1/system_notifications_controller.rb

@@ -0,0 +1,8 @@
+class Api::V1::SystemNotificationsController < Api::V1::BaseController 
+
+    def index 
+      @system_notifications = SystemNotification.where(is_top: true)
+      @system_notifications = kaminary_select_paginate(@system_notifications)
+    end
+
+end

app/views/api/v1/system_notifications/index.json.jbuilder

@@ -0,0 +1,4 @@
+json.total_count @system_notifications.total_count
+json.system_notifications @system_notifications.each do |notification| 
+  json.(notification, :id, :subject, :sub_subject, :content, :is_top)
+end

config/routes/api.rb

@@ -266,6 +266,7 @@ defaults format: :json do
 
       end
 
+      resources :system_notifications, only: [:index]
       resources :projects, only: [:index]
       resources :project_topics, only: [:index, :create, :destroy]
       resources :project_datasets, only: [:index]