从 DialogFragment 调用的 AsyncTask 中的 ProgressDialog 未显示

Question

我正在从 DialogFragment 内部执行 AsyncTask，但在 doInBackground 期间未显示进度条。代码如下：

public class GetCustomerSoapAsync extends AsyncTask<Void, Void, String>
{
  ProgressDialog prg;
  ActionBarActivity activity;
  GetResponseFromGetCustomer listener;


  public GetCustomerSoapAsync(ActionBarActivity activity, GetResponseFromGetCustomer listener)
  {
    this.activity = activity;
    this.listener = listener;
    prg = new ProgressDialog(activity);
    prg.setMessage("Lütfen Bekleyin");
    Log.i("ED","Progress will be shown");
    prg.show();

  }



  @Override protected String doInBackground(Void... params)
  {
    //some stuff
  }

  @Override protected void onPostExecute(String s)
  {
    listener.getResponseFromGetCustomer(s);

    if (prg.isShowing())
    {
        prg.dismiss();
    }

 }

我称之为：

public class B1_PhoneNumberFragment extends android.support.v4.app.Fragment
{
 ...
  buttonLogin.setOnClickListener(new OnClickListener()
    {

        @Override
        public void onClick(View v)
        {
          ...


          PhoneNumberVerified dialog = new PhoneNumberVerified();
                dialog.show(getFragmentManager(), "NumberVerifiedByUser");

        }
        ...
    }
   ....



  public class PhoneNumberVerified extends DialogFragment
  {

   @Override
   public Dialog onCreateDialog(Bundle savedInstanceState)
   {
     // Use the Builder class for convenient dialog construction
     AlertDialog.Builder builder = new AlertDialog.Builder(getActivity());
     // Format of this dialog will be changed
     builder.setMessage("Numaranız doğru mu?\n" + "0" + number)
                .setPositiveButton(R.string.yes,
                        new DialogInterface.OnClickListener()
                        {
                            public void onClick(DialogInterface dialog,
                                                int id)
                            {
                                GlobalApplication.getUser().setPhone(
                                        (excludeParanthesis
                                                (number)));

                                //AsyncTask is not working properly,
                                // progress dialog is not shown and code flows before
                                // response is set to s
                                GetCustomerSoapAsync getCustomerSoapAsync =
                                        new GetCustomerSoapAsync(
                                                (ActionBarActivity) getActivity(),
                                                new GetResponseFromGetCustomer()

                                                {
                                                    @Override
                                                    public void getResponseFromGetCustomer
                                                            (String s)
                                                    {
                                                        response = s;
                                                    }
                                                });

                                getCustomerSoapAsync.execute();


                                Log.i("ED", "Response after GetCustomerSoapAsync callback: " +
                                            response);

}

最后，可能是由于任务流程有缺陷或其他原因，回调无法完成其工作，并且响应未设置为 AsyncTask 的返回值。

感谢您的帮助！

Answer 1

你应该使用onPreExecute：

class Task1 extends AsyncTask<Object, Void, String []> {

    /** The Progress dialog. */
    private final ProgressDialog dialog = new ProgressDialog(YourActivity.this);


    /**
     * Set the Progress dialog.
     */
    protected void onPreExecute() 
    {
    super.onPreExecute();
    this.dialog.setMessage("Loading...");
    this.dialog.show();
    dialog.setCanceledOnTouchOutside(false);
    }


    protected String[] doInBackground(Object... params) {
        ///
    }

    protected void onPostExecute(String [] result) 
    {
        super.onPostExecute(result);
        this.dialog.dismiss();
    }

}

你应该这样称呼它：

Task1 myTask = new Task1();    
myTask.execute(stopArrey, start, end);

希望对您有所帮助！ :)

Answer 2

只需要在 UI Thread 上对 ProgressDialog 进行操作。

asynctask 上的构造函数提供了足够的灵活性，可以将任务放入它自己的类中。注意：在您的自定义 AsyncTask 的构造函数中初始化的任何字段都利用 java final 关键字非常重要，因此字段变量会自动为垃圾回收。

解决方案 ProgressDialog 代码需要在 onPreExecute() 中调用，其中任务仍在 UI 线程上。

public class GetCustomerSoapAsync extends AsyncTask<Void, Void, String>
{
ProgressDialog prg;
// use final for fields initialized in a constructor.
final ActionBarActivity activity;
final GetResponseFromGetCustomer listener;

//下面的例子从调用者那里传入了已经显示的ProgressDialog。将其传入以访问异步任务发布 Progress 方法。在监听器方法中关闭 ProgressDialog；你没有向你的听众展示，所以这只是一种技巧

 public GetCustomerSoapAsync(ActionBarActivity activity, GetResponseFromGetCustomer     listener, ProgressDialog prg)
{
  this.activity = activity;
  this.listener = listener;
  this.prg = prg;

 // or move this code to onPreExecute() where it runs on the UI thread.
// move this code to onPreExecute() 
//prg = new ProgressDialog(activity);
//prg.setMessage("Lütfen Bekleyin");
//Log.i("ED","Progress will be shown");
//prg.show();

}

Answer 3

好的，我认为您必须在执行 Aysnch 任务之前在用户可见的布局中声明 PD。

例如：

//Declare the pd here. Pd private to class.
private ProgressDialog pd;
    builder.setMessage("Numaranız doğru mu?\n" + "0" + number)
                    .setPositiveButton(R.string.yes,
                            new DialogInterface.OnClickListener()
                            {
                              ....
                             pd = ProgressDialog.show(getActivity(), "",
                            "Your Message Here!!!", false);
                            // Now using a modified constructor call your execute function
                           //Previous parametes + pd
                           GetCustomerSoapAsync gCSA = new GetCustomerSoapAsync(...,...,pd);
                           getCustomerSoapAsync.execute();

    }

然后在你的异步类中：

public class GetCustomerSoapAsync extends AsyncTask<Void, Void, String>
{
  ProgressDialog prg;
  ActionBarActivity activity;
  GetResponseFromGetCustomer listener;


      public GetCustomerSoapAsync(ActionBarActivity activity, GetResponseFromGetCustomer listener,ProgressDialog pd)
      ProgressDialog prg;
      {
        this.activity = activity;
        this.listener = listener;
        this.prg = pd;

      }



      @Override protected String doInBackground(Void... params)
      {
        //some stuff
      }

      @Override protected void onPostExecute(String s)
      {
        listener.getResponseFromGetCustomer(s);

        if (prg.isShowing())
        {
            prg.dismiss();
        }

     }

Ps：我不知道您是否使用片段作为实现，但如果是，则必须通过 rootview 引用您在片段中的 onclick 函数中调用的同一 pd，否则您可能会在进度对话框中调用函数一开始就没有表现出来。