在android中，如果我在线程中运行网络请求但是在响应回来之前不想刷新UI，我该怎么办？

Question

就像我需要检查用户名是否已存在于数据库中一样，程序在响应到达之前不会继续。

Answer 1

看来你需要asynctask，这是一个如何使用它的例子..

    public class YourFragment extends Fragment implements YourAsyncTask.YourInterface {


    public YourFragment() {
        // Required empty public constructor
    }


    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {

        View view =  inflater.inflate(R.layout.fragment_your, container, false);



        //do your initial things
        .
        .
        .

        YourAsyncTask yourAsyncTask = new YourAsyncTask(this);
        yourAsyncTask.execute();

        return view;
    }

    @Override
    public void onJobFinishListener(YourDataType yourData) {
        //when this method is trigered by your asynctask 
        //it means that you are in ui thread and update your ui component

        //TODO: update ui component with your data
    }
}

这是asynctask;

public class YourAsyncTask extends AsyncTask {

    private YourInterface yourInterfaceListener;

    private YourDataType yourData; //this data should be calculated in doInBackground method and send via interface

    public YourAsyncTask(YourInterface yourInterfaceListener) {
        this.yourInterfaceListener = yourInterfaceListener;
    }

    @Override
    protected Object doInBackground(Object[] objects) {
        //do your all background tasks here
        .
        .
        .
        yourData = do something here to fill your data..

        return null;
    }

    @Override
    protected void onPostExecute(Object o) {
        super.onPostExecute(o);
        yourInterfaceListener.onJobFinishListener(yourData);
    }

    public interface YourInterface{
        void onJobFinishListener(YourDataType yourData);
    }
}

Answer 2

使用AsyncTask执行网络操作

public class TalkToServer extends AsyncTask<Void, Void, Void> {
    @Override
    protected void onPreExecute() {
       /*
        *    do things before doInBackground() code runs
        *    such as preparing and showing a Dialog or ProgressBar
       */
    }

    @Override
    protected void onProgressUpdate(Void... values) {
       /*
        *    updating data
        *    such a Dialog or ProgressBar
       */

     }

     @Override
     protected Void doInBackground(Void... params) {
        //do your work here
        return null;
     }

     @Override
     protected void onPostExecute(Void result) {
          /*
           *    do something with data here
           *    display it or send to mainactivity
           *    close any dialogs/ProgressBars/etc...
          */
     }
  }

你可以使用它来执行它

TalkToServer myTask = new MyTask(); // can add params for a constructor if needed
myTask.execute(); // here is where you would pass data to doInBackground()

在网络调用完成并且响应获得onPostExecute()被调用。如果AsyncTask在你的activity的内部类中，你可以更新onPostExecute()内的UI。否则你可以使用Interface创建callback到activity。

你可以找到AsyncTask Docs here

Answer 3

您必须使用异步任务。然后你可以在你的激活这个你想要的..get方法中使用你的you_async_class.execute（）。get（）。主线程将等待您的异步任务。你必须改变your_async_class扩展AsyncTask