Question

我希望在从服务器中检索数据时，在onpreexecute和onpost执行时显示progreebar而不是progressdialog。

这是我的异步方法

@Override
protected void onPreExecute() {
    super.onPreExecute();
    m_ProgressBar = new ProgressBar(getActivity(), null, R.layout.progress_bar);
    m_ProgressBar = (ProgressBar) m_Main.findViewById(R.id.progressbar);
    m_ProgressBar.setVisibility(View.VISIBLE);
}

这个进度条在progress_bar布局中，这是一个单独的布局，这个onPreecute方法在登录类中

Answer 1

Below code snippet uses will help you

private class SaveImageTask extends AsyncTask<Bitmap,Void,Void>{

    ProgressDialog progressDialog;

    @Override
    protected void onPreExecute() {
        super.onPreExecute();
        progressDialog = new ProgressDialog(MainActivity.this);
        progressDialog.setMessage("Saving image....");
        progressDialog.show();
    }

    @Override
    protected Void doInBackground(Bitmap... params) {
        Bitmap bitmap = params[0];
        FileOutputStream out = null;
        String timeStamp = new SimpleDateFormat("yyyy_MM_dd_HH_mm_ss").format(new Date());
        createDirectory();
        try {
            out = new FileOutputStream(new File(Environment.getExternalStorageDirectory()+"/"+Environment.DIRECTORY_PICTURES+"/QuoteCards/IMG_"+timeStamp+".png"));
            bitmap.compress(Bitmap.CompressFormat.PNG, 100, out); // bmp is your Bitmap instance
            // PNG is a lossless format, the compression factor (100) is ignored
        } catch (Exception e) {
            e.printStackTrace();
        } finally {
            try {
                if (out != null) {
                    out.close();
                }
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
        return null;
    }

    @Override
    protected void onPostExecute(Void aVoid) {
        super.onPostExecute(aVoid);
        progressDialog.dismiss();
        frameLayout.destroyDrawingCache();
        Toast.makeText(MainActivity.this,"Image has been saved in SD Card",Toast.LENGTH_SHORT).show();
        scan();
    }

}

Answer 2

普通模板就是这样的

private class MyAsyncTask extends AsyncTask<String, Void, Bitmap> {
   protected void onPreExecute() {         
     progressBar.setVisibility(ProgressBar.VISIBLE);
   }

   protected Bitmap doInBackground(String... strings) {
     Bitmap = downloadImageFromUrl(strings[0]);
     return someBitmap;
   }

   protected void onProgressUpdate(Progress... values) {
    progressBar.setProgress(values[0]);
   }  

   protected void onPostExecute(Bitmap result) {
     imageView.setImageBitmap(result);
     // Hide the progress bar
     progressBar.setVisibility(ProgressBar.INVISIBLE);
 }
}

Answer 3

使用的代码是这样的..我创建了一个单独的diloag.xml并在其中包含进度条..

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="wrap_content"
    android:layout_height="65dp"
    android:background="@android:color/background_dark"
    android:orientation="vertical">

<TextView
    android:id="@+id/progress_text"
    android:layout_width="wrap_content"
    android:layout_height="40dp"
    android:layout_above="@+id/progress_bar"
    android:layout_marginLeft="10dp"
    android:layout_marginStart="10dp"
    android:background="@android:color/transparent"
    android:gravity="center_vertical"
    android:text=""
    android:textColor="@android:color/white"
    android:textSize="16sp"
    android:visibility="gone" />

<ProgressBar
    android:id="@+id/progress_bar"
    style="@android:style/Widget.DeviceDefault.ProgressBar.Horizontal"
    android:layout_width="match_parent"
    android:layout_height="30dp"
    android:layout_alignParentBottom="true"
    android:layout_alignParentLeft="true"
    android:layout_alignParentStart="true"
    android:layout_gravity="center"
    android:background="@color/cardview_dark_background"
    android:maxHeight="20dp"
    android:minHeight="20dp" />

</RelativeLayout>

和onCreate或onCreateView上的java代码初始化了Dialog

    dialog = new Dialog(getActivity());
    dialog.requestWindowFeature(Window.FEATURE_NO_TITLE);
    dialog.setContentView(R.layout.prograss_bar_dialog);

并且还编写了两个函数，如showPB（）和hidePB（）

   public void showPB(String message) {
    progressBar = (ProgressBar) dialog.findViewById(R.id.progress_bar);
    TextView progressText = (TextView)   dialog.findViewById(R.id.progress_text);
    progressText.setText("" + message);
    progressText.setVisibility(View.VISIBLE);
    progressBar.setVisibility(View.VISIBLE);
    progressBar.setIndeterminate(true);
    dialog.setCancelable(false);
    dialog.setCanceledOnTouchOutside(false);
    dialog.show();
    }


    public void hidePB() {
    //if (dialog != null) {
    dialog.dismiss();
     //}
    }

并随时打电话，并确保调用hidePB（）

希望这会有所帮助

Answer 4

首先将ProgressBar视图添加到布局

<ProgressBar
        android:id="@+id/progress"
        android:layout_width="24dp"
        android:layout_height="24dp"
        android:visibility="invisible" />

在MyAwesomeAsynkTaskClass中初始化进度条，如

private ProgressBar mProgressBar;

通过以下步骤修改onPreExecute（）和onPostExecute（）：

protected void onPreExecute() {
    super.onPreExecute();

    mProgressBar.setVisibility(View.VISIBLE);
}

和

protected void onPostExecute(Void aVoid) {
    super.onPostExecute(aVoid);

    mProgressBar.setVisibility(View.GONE); 
}

如何在android中的AsynkTask中显示Progressbar

4 个答案: