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試圖在後臺解析與AsyncTask的JSON時強制關閉

2011-01-08 43 views
0

我是新來的android開發，我玩json數據。我設法讓解析工作。我想顯示一個ProgressDialog，我讀到我需要使用AsyncTask。但由於某種原因，只要我在doInBackground（）內部放置相同的工作代碼，就會收到一個強制關閉的事件，儘管eclipse說一切都很好。試圖在後臺解析與AsyncTask的JSON時強制關閉

這裏是源代碼：

public class HomeActivity extends Activity { 


    public class BackgroundAsyncTask extends AsyncTask<Void, Integer, Void> { 

     ProgressDialog dialog = new ProgressDialog (HomeActivity.this); 


     @Override 
     protected void onPreExecute() { 
     dialog.setMessage("Loading...please wait"); 
     dialog.setIndeterminate(true); 
     dialog.setCancelable(false); 
     dialog.show(); 
     } 

     protected void onPostExecute() { 
      dialog.dismiss(); 
      } 

     @Override 
     protected Void doInBackground(Void... params) {   
      try { 
       URL json = new URL("http://www.corps-marchia.de/jsontest.php"); 
       URLConnection tc = json.openConnection(); 
       BufferedReader in = new BufferedReader(new InputStreamReader(tc.getInputStream())); 

       String line; 
       while ((line = in.readLine()) != null) { 
        JSONArray ja = new JSONArray(line); 
        JSONObject jo = (JSONObject) ja.get(0); 
        TextView txtView = (TextView)findViewById(R.id.TextView01); 
        txtView.setText(jo.getString("text")); 
       } 
      } catch (MalformedURLException e) { 
       e.printStackTrace(); 
      } catch (IOException e) { 
       e.printStackTrace(); 
      } catch (JSONException e) { 
       e.printStackTrace(); 
      } 

     return null; 
     } 
    } 


    @Override 
    public void onCreate(Bundle savedInstanceState) { 
     super.onCreate(savedInstanceState); 
     setContentView(R.layout.main); 

     new BackgroundAsyncTask().execute(); 
    } 

}

以下是錯誤日誌：

01-08 12:33:48.225: ERROR/AndroidRuntime(815): FATAL EXCEPTION: AsyncTask #1 
01-08 12:33:48.225: ERROR/AndroidRuntime(815): java.lang.RuntimeException: An error occured while executing doInBackground() 
01-08 12:33:48.225: ERROR/AndroidRuntime(815):  at android.os.AsyncTask$3.done(AsyncTask.java:200) 
01-08 12:33:48.225: ERROR/AndroidRuntime(815):  at java.util.concurrent.FutureTask$Sync.innerSetException(FutureTask.java:274) 
01-08 12:33:48.225: ERROR/AndroidRuntime(815):  at java.util.concurrent.FutureTask.setException(FutureTask.java:125) 
01-08 12:33:48.225: ERROR/AndroidRuntime(815):  at java.util.concurrent.FutureTask$Sync.innerRun(FutureTask.java:308) 
01-08 12:33:48.225: ERROR/AndroidRuntime(815):  at java.util.concurrent.FutureTask.run(FutureTask.java:138) 
01-08 12:33:48.225: ERROR/AndroidRuntime(815):  at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1088) 
01-08 12:33:48.225: ERROR/AndroidRuntime(815):  at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:581) 
01-08 12:33:48.225: ERROR/AndroidRuntime(815):  at java.lang.Thread.run(Thread.java:1019) 
01-08 12:33:48.225: ERROR/AndroidRuntime(815): Caused by: android.view.ViewRoot$CalledFromWrongThreadException: Only the original thread that created a view hierarchy can touch its views. 
01-08 12:33:48.225: ERROR/AndroidRuntime(815):  at android.view.ViewRoot.checkThread(ViewRoot.java:2932) 
01-08 12:33:48.225: ERROR/AndroidRuntime(815):  at android.view.ViewRoot.requestLayout(ViewRoot.java:629) 
01-08 12:33:48.225: ERROR/AndroidRuntime(815):  at android.view.View.requestLayout(View.java:8267) 
01-08 12:33:48.225: ERROR/AndroidRuntime(815):  at android.view.View.requestLayout(View.java:8267) 
01-08 12:33:48.225: ERROR/AndroidRuntime(815):  at android.view.View.requestLayout(View.java:8267) 
01-08 12:33:48.225: ERROR/AndroidRuntime(815):  at android.view.View.requestLayout(View.java:8267) 
01-08 12:33:48.225: ERROR/AndroidRuntime(815):  at android.view.View.requestLayout(View.java:8267) 
01-08 12:33:48.225: ERROR/AndroidRuntime(815):  at android.widget.TextView.checkForRelayout(TextView.java:5521) 
01-08 12:33:48.225: ERROR/AndroidRuntime(815):  at android.widget.TextView.setText(TextView.java:2724) 
01-08 12:33:48.225: ERROR/AndroidRuntime(815):  at android.widget.TextView.setText(TextView.java:2592) 
01-08 12:33:48.225: ERROR/AndroidRuntime(815):  at android.widget.TextView.setText(TextView.java:2567) 
01-08 12:33:48.225: ERROR/AndroidRuntime(815):  at net.ajzele.demo.andy1.HomeActivity$BackgroundAsyncTask.doInBackground(HomeActivity.java:52) 
01-08 12:33:48.225: ERROR/AndroidRuntime(815):  at net.ajzele.demo.andy1.HomeActivity$BackgroundAsyncTask.doInBackground(HomeActivity.java:1) 
01-08 12:33:48.225: ERROR/AndroidRuntime(815):  at android.os.AsyncTask$2.call(AsyncTask.java:185) 
01-08 12:33:48.225: ERROR/AndroidRuntime(815):  at java.util.concurrent.FutureTask$Sync.innerRun(FutureTask.java:306) 
01-08 12:33:48.225: ERROR/AndroidRuntime(815):  ... 4 more 
01-08 12:33:51.605: ERROR/WindowManager(815): Activity net.ajzele.demo.andy1.HomeActivity has leaked window [email protected] that was originally added here 
01-08 12:33:51.605: ERROR/WindowManager(815): android.view.WindowLeaked: Activity net.ajzele.demo.andy1.HomeActivity has leaked window [email protected] that was originally added here 
01-08 12:33:51.605: ERROR/WindowManager(815):  at android.view.ViewRoot.<init>(ViewRoot.java:258) 
01-08 12:33:51.605: ERROR/WindowManager(815):  at android.view.WindowManagerImpl.addView(WindowManagerImpl.java:148) 
01-08 12:33:51.605: ERROR/WindowManager(815):  at android.view.WindowManagerImpl.addView(WindowManagerImpl.java:91) 
01-08 12:33:51.605: ERROR/WindowManager(815):  at android.view.Window$LocalWindowManager.addView(Window.java:424) 
01-08 12:33:51.605: ERROR/WindowManager(815):  at android.app.Dialog.show(Dialog.java:241) 
01-08 12:33:51.605: ERROR/WindowManager(815):  at net.ajzele.demo.andy1.HomeActivity$BackgroundAsyncTask.onPreExecute(HomeActivity.java:33) 
01-08 12:33:51.605: ERROR/WindowManager(815):  at android.os.AsyncTask.execute(AsyncTask.java:391) 
01-08 12:33:51.605: ERROR/WindowManager(815):  at net.ajzele.demo.andy1.HomeActivity.onCreate(HomeActivity.java:72) 
01-08 12:33:51.605: ERROR/WindowManager(815):  at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1047) 
01-08 12:33:51.605: ERROR/WindowManager(815):  at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1586) 
01-08 12:33:51.605: ERROR/WindowManager(815):  at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:1638) 
01-08 12:33:51.605: ERROR/WindowManager(815):  at android.app.ActivityThread.access$1500(ActivityThread.java:117) 
01-08 12:33:51.605: ERROR/WindowManager(815):  at android.app.ActivityThread$H.handleMessage(ActivityThread.java:928) 
01-08 12:33:51.605: ERROR/WindowManager(815):  at android.os.Handler.dispatchMessage(Handler.java:99) 
01-08 12:33:51.605: ERROR/WindowManager(815):  at android.os.Looper.loop(Looper.java:123) 
01-08 12:33:51.605: ERROR/WindowManager(815):  at android.app.ActivityThread.main(ActivityThread.java:3647) 
01-08 12:33:51.605: ERROR/WindowManager(815):  at java.lang.reflect.Method.invokeNative(Native Method) 
01-08 12:33:51.605: ERROR/WindowManager(815):  at java.lang.reflect.Method.invoke(Method.java:507) 
01-08 12:33:51.605: ERROR/WindowManager(815):  at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:839) 
01-08 12:33:51.605: ERROR/WindowManager(815):  at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:597) 
01-08 12:33:51.605: ERROR/WindowManager(815):  at dalvik.system.NativeStart.main(Native Method)

任何提示？我希望你能幫助我，香港專業教育學院搜查了網，並沒有找到任何有效的解決方案......提前

來源

2011-01-08 robs

回答

2

檢查docs for AsyncTask。您不能直接在doInBackground內操作UI。爲了進行UI更新，您需要撥打publishProgress。您還需要更改AsyncTask的簽名才能通過String。所以像這樣：

public class BackgroundAsyncTask extends AsyncTask<Void, String, Void> { 
    TextView txtView = (TextView)findViewById(R.id.TextView01); 
    ... 
    protected void onProgressUpdate(String... message) { 
     txtView.setText(message[0]); 
    } 
    ... 
    @Override 
    protected Void doInBackground(Void... params) { 
     try { 
      URL json = new URL("http://www.corps-marchia.de/jsontest.php"); 
      URLConnection tc = json.openConnection(); 
      BufferedReader in = new BufferedReader(new InputStreamReader(tc.getInputStream())); 

      String line; 
      while ((line = in.readLine()) != null) { 
       JSONArray ja = new JSONArray(line); 
       JSONObject jo = (JSONObject) ja.get(0); 
       publishProgress(jo.getString("text")); 
      } 
     } catch (MalformedURLException e) { 
      e.printStackTrace(); 
     } catch (IOException e) { 
      e.printStackTrace(); 
     } catch (JSONException e) { 
      e.printStackTrace(); 
     } 

    return null; 
    }

來源

2011-01-08 13:11:30

+0

謝謝！它的工作就像一個魅力！我不知道你無法從背景進行UI更改。 dialog.dismiss（）不工作onPostExecute（）雖然，任何想法爲什麼？ progressdialog作爲用戶界面還算不算？ – robs 2011-01-08 13:58:01

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