如何从 asynctask 更新 ui [英] How to update ui from asynctask

问题描述

我已经看到很多关于如何执行此操作的示例，但我无法弄清楚如何在我的代码中实现它.

I've seen many examples of how to do this, but I can't figure how to implement it in my code.

我正在使用这个代码.
我已经更新了 url，所以它会收到一个带有动态数据的 json.我想要做的是使用此代码每 30 秒自动更新一次列表.

I am using this code.
I have updated the url, so it will receive a json with dynamic data. What I'm trying to do is to automatically update the list every 30 secs with this code.

Handler handler = new Handler();
    Runnable refresh = new Runnable() {
        public void run() {
            new GetContacts().execute();
            handler.postDelayed(refresh, 30000); 
        }
    };

刷新，调用url获取数据，但是UI没有更新.

It refreshes, and calls the url and gets the data, but the UI does not get updated.

感谢您为我指明正确方向的任何提示.

Thanks for any hints to point me in the right direction.

http://www.androidhive.info/2012/01/android-json-解析教程/

推荐答案

您在 AsyncTask 中有三个可与 UI 交互的受保护方法.

You have three protected methods in an AsyncTask that can interact with the UI.

• onPreExecute()
  • 运行之前 doInBackground()
  • 运行 doInBackground() 完成
  • 这仅在 doInBackground() 使用 publishProgress() 调用它时运行
  • this only runs when doInBackground() calls it with publishProgress()

  如果在您的情况下，任务运行的时间比您想要刷新的 30 秒长很多，您将需要使用 onProgressUpdate() 和 publishProgress().否则 onPostExecute() 应该可以解决问题.

  If in your case the Task runs for a lot longer than the 30 seconds you want to refresh you would want to make use of onProgressUpdate() and publishProgress(). Otherwise onPostExecute() should do the trick.

  有关如何实现它，请参阅官方文档.

  See the official documentation for how to implement it.

  这篇关于如何从 asynctask 更新 ui的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！