aSync任務不能執行兩次

我正在處理需要將文件上傳到服務器的應用程序。但把它上傳需要登錄（工作）的文件，然後獲得url（工作），然後上傳（強制關閉）aSync任務不能執行兩次

的logcat的：

10-13 14:10:27.494: E/AndroidRuntime(26578): FATAL EXCEPTION: main 
10-13 14:10:27.494: E/AndroidRuntime(26578): java.lang.IllegalStateException: Cannot execute task: the task has already been executed (a task can be executed only once) 
10-13 14:10:27.494: E/AndroidRuntime(26578): at android.os.AsyncTask.executeOnExecutor(AsyncTask.java:578) 
10-13 14:10:27.494: E/AndroidRuntime(26578): at android.os.AsyncTask.execute(AsyncTask.java:534) 
10-13 14:10:27.494: E/AndroidRuntime(26578): at com.spxc.bayfiles.FilesActivity.onOptionsItemSelected(FilesActivity.java:294) 
10-13 14:10:27.494: E/AndroidRuntime(26578): at com.actionbarsherlock.app.SherlockActivity.onMenuItemSelected(SherlockActivity.java:208) 
10-13 14:10:27.494: E/AndroidRuntime(26578): at com.actionbarsherlock.ActionBarSherlock.callbackOptionsItemSelected(ActionBarSherlock.java:603) 
10-13 14:10:27.494: E/AndroidRuntime(26578): at com.actionbarsherlock.internal.ActionBarSherlockNative.dispatchOptionsItemSelected(ActionBarSherlockNative.java:93) 
10-13 14:10:27.494: E/AndroidRuntime(26578): at com.actionbarsherlock.app.SherlockActivity.onOptionsItemSelected(SherlockActivity.java:159) 
10-13 14:10:27.494: E/AndroidRuntime(26578): at android.app.Activity.onMenuItemSelected(Activity.java:2566) 
10-13 14:10:27.494: E/AndroidRuntime(26578): at com.android.internal.policy.impl.PhoneWindow.onMenuItemSelected(PhoneWindow.java:986) 
10-13 14:10:27.494: E/AndroidRuntime(26578): at com.android.internal.view.menu.MenuBuilder.dispatchMenuItemSelected(MenuBuilder.java:735) 
10-13 14:10:27.494: E/AndroidRuntime(26578): at com.android.internal.view.menu.MenuItemImpl.invoke(MenuItemImpl.java:152) 
10-13 14:10:27.494: E/AndroidRuntime(26578): at com.android.internal.view.menu.MenuBuilder.performItemAction(MenuBuilder.java:874) 
10-13 14:10:27.494: E/AndroidRuntime(26578): at com.android.internal.view.menu.ActionMenuView.invokeItem(ActionMenuView.java:547) 
10-13 14:10:27.494: E/AndroidRuntime(26578): at com.android.internal.view.menu.ActionMenuItemView.onClick(ActionMenuItemView.java:115) 
10-13 14:10:27.494: E/AndroidRuntime(26578): at android.view.View.performClick(View.java:4240) 
10-13 14:10:27.494: E/AndroidRuntime(26578): at android.view.View$PerformClick.run(View.java:17721) 
10-13 14:10:27.494: E/AndroidRuntime(26578): at android.os.Handler.handleCallback(Handler.java:730) 
10-13 14:10:27.494: E/AndroidRuntime(26578): at android.os.Handler.dispatchMessage(Handler.java:92) 
10-13 14:10:27.494: E/AndroidRuntime(26578): at android.os.Looper.loop(Looper.java:137) 
10-13 14:10:27.494: E/AndroidRuntime(26578): at android.app.ActivityThread.main(ActivityThread.java:5103) 
10-13 14:10:27.494: E/AndroidRuntime(26578): at java.lang.reflect.Method.invokeNative(Native Method) 
10-13 14:10:27.494: E/AndroidRuntime(26578): at java.lang.reflect.Method.invoke(Method.java:525) 
10-13 14:10:27.494: E/AndroidRuntime(26578): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:737) 
10-13 14:10:27.494: E/AndroidRuntime(26578): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:553) 
10-13 14:10:27.494: E/AndroidRuntime(26578): at de.robv.android.xposed.XposedBridge.main(XposedBridge.java:112) 
10-13 14:10:27.494: E/AndroidRuntime(26578): at dalvik.system.NativeStart.main(Native Method)

我的代碼：（handleJsonObject）：

private void handleJsonObject(JSONObject object) { 

     try { 
      sUpload = object.getString("uploadUrl");    
      HttpClient httpclient = new DefaultHttpClient(); 

      //post request to send the video 

      File sdCardRoot = Environment.getExternalStorageDirectory(); 
      File myDir = new File(sdCardRoot, "Download"); 

      HttpPost httppost = new HttpPost(sUpload); 
      StrictMode.ThreadPolicy policy = new StrictMode.ThreadPolicy.Builder().permitAll().build(); 
      StrictMode.setThreadPolicy(policy); 
      FileBody video_file1 = new FileBody(new File(myDir + "/test.txt")); 
      MultipartEntity reqEntity = new MultipartEntity(); 
      reqEntity.addPart("file=", video_file1);      
      httppost.setEntity(reqEntity); 

      // DEBUG 
      System.out.println("executing request " + httppost.getRequestLine()); 
      HttpResponse response = null; 
      try { 
       response = httpclient.execute(httppost); 
      } catch (ClientProtocolException e) { 
       // TODO Auto-generated catch block 
       e.printStackTrace(); 
      } catch (IOException e) { 
       // TODO Auto-generated catch block 
       e.printStackTrace(); 
      } 
      HttpEntity resEntity = response.getEntity(); 

      // DEBUG 
      System.out.println(response.getStatusLine()); 
      if (resEntity != null) { 
       try { 
       System.out.println(EntityUtils.toString(resEntity)); 
      } catch (org.apache.http.ParseException e) { 
       // TODO Auto-generated catch block 
       e.printStackTrace(); 
      } catch (IOException e) { 
       // TODO Auto-generated catch block 
       e.printStackTrace(); 
      } 
      } // end if 
      if (resEntity != null) { 
       try { 
       resEntity.consumeContent(); 
      } catch (IOException e) { 
       // TODO Auto-generated catch block 
       e.printStackTrace(); 
      } 
      } // end if 

      httpclient.getConnectionManager().shutdown(); 


     } catch (JSONException e) { 
      Log.e("log_tag", "Error parsing data: " + e.toString()); 
      Crouton.makeText(this, "Something went wrong!", Style.ALERT).show(); 
     } 
    }

代碼（異步）它調用郵編（handleJsonObject）：

asyncTask.setJsonListener(new JsonListener() { 
       public void onObjectReturn(JSONObject object) { 
        handleJsonObject(object); 
       } 
      }); 
      asyncTask.execute("http://api.bayfiles.net/v1/file/uploadUrl?session=" + sessionId);

我不能figu回顧爲什麼代碼不起作用？任何幫助非常感謝！

來源

2013-10-13 Stian Instebo

錯誤來源於您的活動。您需要發佈該代碼。 – SBerg413

正如例外本身所解釋的那樣，除非您創建一個new實例並致電.execute，否則您不能多次執行AsyncTask。

例如：

async = new AsyncTask(); 
async.execute();

*爲了執行多次，您需要重新創建（使用new）要的次數執行它的實例。

來源

2013-10-13 12:22:08 waqaslam

我簡單地稱它爲一次？我不？ –

沒關係:)得到它的工作，謝謝:) –

這不起作用 – Darrell

-1

您不能多次執行AsyncTask，因此要修復此錯誤，只需將其包裝在如下條件中： async = new AsyncTask（）;

    if (async==null){ 

        async.execute(); 

        }

當您嘗試在viewpager中運行Asynctask時，通常會發生此錯誤。當您在片段中運行asynctask並滑動到下一個片段時，返回到前一個片段將觸發該片段中的asynctask的重新執行，從而導致應用程序崩潰。因此你必須檢查一下asynctask是否已經通過將它包裝在一個條件中來執行。

來源

2014-10-17 04:27:34

我使用此代碼和它的作品對我來說：

if ((eliminar_op_async != null) && eliminar_op_async.getStatus() == AsyncTask.Status.RUNNING) { 
     if (eliminar_op_async.isCancelled()) { 
      eliminar_op_async = new EliminarOperacion(); 

      eliminar_op_async.execute(id_operacion,posicion_operacion); 
     } 
     else { 
      // Nada 
     } 
    } 

    if ((eliminar_op_async != null) && eliminar_op_async.getStatus() == AsyncTask.Status.PENDING) { 
     eliminar_op_async.execute(id_operacion,posicion_operacion); 
    } 

    if ((eliminar_op_async != null) && eliminar_op_async.getStatus() == AsyncTask.Status.FINISHED) { 
     eliminar_op_async = new EliminarOperacion(); 

     eliminar_op_async.execute(id_operacion,posicion_operacion); 
    } 

    if (eliminar_op_async == null) { 
     eliminar_op_async = new EliminarOperacion(); 

     eliminar_op_async.execute(id_operacion,posicion_operacion); 
    }

來源

2014-12-19 23:53:34

你可以通過調用異步實例與async.cancel（真）取消，這樣就可以保證有異步只有一個實例

來源

2016-07-14 07:40:46

aSync任務不能執行兩次

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