如何检查新的JSON文件是否可用？ [英] How to check if new JSON file is available?

问题描述

我正在构建一个从Java后端获取所有信息的移动应用程序。数据可通过REST以JSON格式获得。如果JSON是新的，你将如何设法在移动设备上发现？我想有一个非常简单的JSON格式文件，只有一个时间戳，移动设备每次检查时都会与已存储的内容进行比较......但它似乎不是一个好的解决方案，至少我认为。那么有其他方法可以做到这一点吗？我正在开发后端Java服务器应用程序和移动设备应用程序（iOS）。

I am building a mobile application that get all the information from a Java backend. The data is available through REST in JSON format. How would you manage to discover on the mobile device if the JSON is new or not? I was thinking of having one really simple JSON format file with only a timestamp that the mobile device checked each time to compare to what already stored...but it doesn't seems to be a good solution, at least I think. So are there other ways to do this? I am developing both the backend Java server application and the mobile device app (iOS).

推荐答案

使用 HTTP标头，包括 HTTP ETag 。这是 Java中的示例。

If-Modified-Since   
Allows a 304 Not Modified to be returned if content is unchanged    

If-None-Match   
Allows a 304 Not Modified to be returned if content is unchanged

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