活動指示器不適用於異步任務

Question

當我使用asynctask方法時，活動指示器不起作用。 AsyncTask方法用於從URL下載圖像並放在手機內存中。下面是我的代碼

btnSubmit.setOnClickListener(new OnClickListener() { 

     @Override 
     public void onClick(View v) { 

      AsyncCallWS aws = new AsyncCallWS(); 

      try { 
       retData = aws.execute().get(); 
       Log.d(TAG, "STATUS is " + retData); 
      } catch (InterruptedException e) { 
       // TODO Auto-generated catch block 
       e.printStackTrace(); 
      } catch (ExecutionException e) { 
       // TODO Auto-generated catch block 
       e.printStackTrace(); 
      } 

      // Close the window and go back to login page 
      Intent intent = new Intent(launchar.this, arcamera.class); 
      intent.putExtra("url", url_); 
      intent.putExtra(Strings.USERNAME, mUsername); 
      intent.putExtra(Strings.PASSWORD, mPassword); 
      intent.putExtra(Strings.COMP_ID, mCompId); 
      startActivity(intent); 


     } 
    }); 

我的異步方法如下：

private class AsyncCallWS extends AsyncTask<String, Void, String> { 

    @Override 
    protected String doInBackground(String... params) { 
     // Call the service 

     HttpConnectionHelper helper = new HttpConnectionHelper(
       Constants.SERVICE_GETAR_URL); 
     final String REQUEST_DATA = String.format(
       "<ReqData xmlns=\"http://www.ceolution.com/phone\"> " 
         + "<key>%s|%s|%s</key>" + "</ReqData>", mUsername, 
       mPassword, mCompId); 
     try { 
      helper.setRequestMethod(HttpPost.METHOD_NAME); 
      helper.setPostData(REQUEST_DATA); 
      helper.setHeader("Content-Type", "application/xml"); 

      int code = helper.getResponseCode(); 
      if (Constants.LOG_ENABLED) { 
       Log.i(TAG, "Response code = " + code); 
      } 
      if (code == HttpURLConnection.HTTP_OK) { 
       String data = helper.getResponseData(); 
       if (Constants.LOG_ENABLED) { 
        Log.v(TAG, "Response Data - " + data); 
       } 
       ARParser par = new ARParser(); 
       String data_ = par.ParseAR(data); 
       Log.i(TAG, "RETURN DATA IS " + data_); 

       // Get Object 

       BufferedReader br = new BufferedReader(new StringReader(
         data_)); 
       InputSource is = new InputSource(br); 

       // Create XML Parser 
       ARXMLFormatter parser = new ARXMLFormatter(); 

       SAXParserFactory factory = SAXParserFactory.newInstance(); 
       SAXParser sp = factory.newSAXParser(); 
       XMLReader reader = sp.getXMLReader(); 
       reader.setContentHandler(parser); 
       reader.parse(is); 

       myData = parser.itemList; 

       if (myData != null) { 

        String OutputData = ""; 
        Location itemLocation = null; 
        for (Item item : myData) { 
         if (item != null) { 
          itemLocation = new Location(""); 
          itemLocation.setLatitude(Double 
            .parseDouble(item.getLat())); 
          itemLocation.setLongitude(Double 
            .parseDouble(item.getLg())); 

          if (location != null) { 
           float distanceInMeters = itemLocation 
             .distanceTo(location); 
           Log.d(TAG, "distanceInMeters is " 
             + distanceInMeters); 

           if (distanceInMeters <= Double 
             .parseDouble(item.getR())) { 
            // Must have to clean the directory 
            // before 
            // writing data 
            File savefilepath1 = new File(
              COURSE_ZIP_FILE_PATH); 
            cleanDirectory(savefilepath1); 

            Image realData = null; 
            String imageName = ""; 
            for (int k = 0; k < 8; k++) { 
             realData = null; 
             imageName = ""; 
             switch (k) { 
             case 0: { 
              realData = item.getN(); 
              imageName = "n.png"; 

              break; 
             } 
             case 1: { 
              realData = item.getE(); 
              imageName = "e.png"; 
              break; 
             } 
             case 2: { 
              realData = item.getS(); 
              imageName = "s.png"; 
              break; 
             } 
             case 3: { 
              realData = item.getW(); 
              imageName = "w.png"; 
              break; 
             } 
             case 4: { 
              realData = item.getNe(); 
              imageName = "ne.png"; 
              break; 
             } 
             case 5: { 
              realData = item.getNw(); 
              imageName = "nw.png"; 
              break; 
             } 
             case 6: { 
              realData = item.getSe(); 
              imageName = "se.png"; 
              break; 
             } 
             case 7: { 
              realData = item.getSw(); 
              imageName = "sw.png"; 
              break; 
             } 
             } 
             url_[k] = realData.getL(); 
             boolean status = false; 
             if (realData.getU() != "" 
               && realData.getU() != null) 
              status = DownloadFile(
                realData.getU() 
                  .replace(
                    "http", 
                    "https"), 
                imageName); 
             Log.d(TAG, "Download status is " 
               + status); 
            } 

            Log.d(TAG, 
              "This is the item to processed"); 
            return "SUCCESS"; 
           } 

           OutputData = OutputData + item.toString(); 
          } else 
           return "GPSISSUE"; 
         } else 
          Log.e("Items", "No details"); 
        } 

        Log.d(TAG, "OutputData data is " + OutputData); 
       } 

       return "NODATA"; 
      } 
     } catch (Exception ex) { 
      ex.printStackTrace(); 
      return "ERROR"; 
     } 
     return "NODATA"; 
    } 

XML文件是低於

<FrameLayout 

    android:id="@+id/laucnh_layout" 
    android:layout_width="wrap_content" 
    android:layout_height="wrap_content" 
    android:layout_centerInParent="true" > 

<ImageView 
     android:id="@+id/btnSubmit" 
     android:layout_width="wrap_content" 
     android:layout_height="wrap_content" 
     android:adjustViewBounds="true" 
     android:background="@drawable/launch" 
     android:onClick="@string/onClick" 
      android:scaleType="center" /> 
</FrameLayout> 

即使我試圖把活動指示燈在onPreExecute()和onPostExecute()也做不行。

我不確定可能是什麼原因。

請幫忙。

Answer 1

您將不得不從asyncTask發佈更新到UI。這是一個例子。因此，在onProgressUpdate函數中，您可以更新UI。我希望這有幫助。

private class DownloadFilesTask extends AsyncTask<URL, Integer, Long> { 
    protected Long doInBackground(URL... urls) { 
     int count = urls.length; 
     long totalSize = 0; 
     for (int i = 0; i < count; i++) { 
      totalSize += Downloader.downloadFile(urls[i]); 
      publishProgress((int) ((i/(float) count) * 100)); 
      // Escape early if cancel() is called 
      if (isCancelled()) break; 
     } 
     return totalSize; 
    } 

    protected void onProgressUpdate(Integer... progress) { 
     setProgressPercent(progress[0]); 
    } 

    protected void onPostExecute(Long result) { 
     showDialog("Downloaded " + result + " bytes"); 
    } 
}