的Android异步任务NetworkOnMainThreadException

我有一个导航抽屉，一些异步任务将在后台做。我想要做的是从导航抽屉中选择某个项目时，然后执行在异步任务中在后台执行的方法。这里是从抽屉式导航栏中选择一些代码：的Android异步任务NetworkOnMainThreadException

private void selectItem(int position) { 
    selectedPosition = position; 
    mDrawerLayout.closeDrawer(navDrawerView); 

    switch (selectedPosition) { 
    case 0: 
     try { 
      ViewEventsOnMap(); 
     } catch (JSONException e) { 
      e.printStackTrace(); 
     } 
     Toast.makeText(ENeighbourhoodActivity.this, "Press and hold at the area where you wish to create an event!", 
       Toast.LENGTH_LONG).show(); 
     break; 
    case 1: 
     Toast.makeText(ENeighbourhoodActivity.this, "Analyze Event", 
       Toast.LENGTH_LONG).show(); 
     break; 
    } 

    setTitle(mEventSelection[selectedPosition]); 

}

我的异步任务等级：

private class MyAsyncTask extends AsyncTask<Void, Integer, Double> { 
    @Override 
    protected Double doInBackground(Void... params) { 
     try { 
      ViewEventsOnMap(); 
     } catch (JSONException e) { 
      e.printStackTrace(); 
     } 
     return null; 
    } 

    protected void onPostExecute(Double result) { 
    } 

    protected void onProgressUpdate(Integer... progress) { 
    } 
}

我打电话时的onCreate因此它不取决于其选择的项目这个异步任务等级从抽屉导航。

public void ViewEventsOnMap() throws JSONException { 
    String page; 
    JSONArray jsonArray; 

    try { 
     HttpClient client = new DefaultHttpClient(); 
     HttpGet request = new HttpGet(URL); 
     HttpResponse response = client.execute(request); 
     HttpEntity entity = response.getEntity(); 
     try { 
      // Codes to retrieve data from servlet and plot marker onto the map 
      } 
     } catch (JSONException e) { 
      e.printStackTrace(); 
     } 
    } catch (IOException e) { 
     e.printStackTrace(); 
    } 
}

但随着这些代码，我收到以下错误消息：

11-04 20:54:45.642: W/dalvikvm(25527): threadid=1: thread exiting with uncaught exception (group=0x40c3f1f8) 
11-04 20:54:45.673: E/AndroidRuntime(25527): FATAL EXCEPTION: main 
11-04 20:54:45.673: E/AndroidRuntime(25527): android.os.NetworkOnMainThreadException 
11-04 20:54:45.673: E/AndroidRuntime(25527): at android.os.StrictMode$AndroidBlockGuardPolicy.onNetwork(StrictMode.java:1099) 
11-04 20:54:45.673: E/AndroidRuntime(25527): at libcore.io.BlockGuardOs.connect(BlockGuardOs.java:84) 
11-04 20:54:45.673: E/AndroidRuntime(25527): at libcore.io.IoBridge.connectErrno(IoBridge.java:127) 
11-04 20:54:45.673: E/AndroidRuntime(25527): at libcore.io.IoBridge.connect(IoBridge.java:112) 
11-04 20:54:45.673: E/AndroidRuntime(25527): at java.net.PlainSocketImpl.connect(PlainSocketImpl.java:192) 
11-04 20:54:45.673: E/AndroidRuntime(25527): at java.net.PlainSocketImpl.connect(PlainSocketImpl.java:459) 
11-04 20:54:45.673: E/AndroidRuntime(25527): at java.net.Socket.connect(Socket.java:842) 
11-04 20:54:45.673: E/AndroidRuntime(25527): at org.apache.http.conn.scheme.PlainSocketFactory.connectSocket(PlainSocketFactory.java:119) 
11-04 20:54:45.673: E/AndroidRuntime(25527): at org.apache.http.impl.conn.DefaultClientConnectionOperator.openConnection(DefaultClientConnectionOperator.java:144) 
11-04 20:54:45.673: E/AndroidRuntime(25527): at org.apache.http.impl.conn.AbstractPoolEntry.open(AbstractPoolEntry.java:164) 
11-04 20:54:45.673: E/AndroidRuntime(25527): at org.apache.http.impl.conn.AbstractPooledConnAdapter.open(AbstractPooledConnAdapter.java:119) 
11-04 20:54:45.673: E/AndroidRuntime(25527): at org.apache.http.impl.client.DefaultRequestDirector.execute(DefaultRequestDirector.java:360) 
11-04 20:54:45.673: E/AndroidRuntime(25527): at org.apache.http.impl.client.AbstractHttpClient.execute(AbstractHttpClient.java:555) 
11-04 20:54:45.673: E/AndroidRuntime(25527): at org.apache.http.impl.client.AbstractHttpClient.execute(AbstractHttpClient.java:487) 
11-04 20:54:45.673: E/AndroidRuntime(25527): at org.apache.http.impl.client.AbstractHttpClient.execute(AbstractHttpClient.java:465) 
11-04 20:54:45.673: E/AndroidRuntime(25527): at nyp.edu.eneighbourhood.ENeighbourhoodActivity.ViewEventsOnMap(ENeighbourhoodActivity.java:204) 
11-04 20:54:45.673: E/AndroidRuntime(25527): at nyp.edu.eneighbourhood.ENeighbourhoodActivity.selectItem(ENeighbourhoodActivity.java:385) 
11-04 20:54:45.673: E/AndroidRuntime(25527): at nyp.edu.eneighbourhood.ENeighbourhoodActivity.access$4(ENeighbourhoodActivity.java:378) 
11-04 20:54:45.673: E/AndroidRuntime(25527): at nyp.edu.eneighbourhood.ENeighbourhoodActivity$5.onChildClick(ENeighbourhoodActivity.java:341) 
11-04 20:54:45.673: E/AndroidRuntime(25527): at android.widget.ExpandableListView.handleItemClick(ExpandableListView.java:584) 
11-04 20:54:45.673: E/AndroidRuntime(25527): at android.widget.ExpandableListView.performItemClick(ExpandableListView.java:521) 
11-04 20:54:45.673: E/AndroidRuntime(25527): at android.widget.AbsListView$PerformClick.run(AbsListView.java:2713) 
11-04 20:54:45.673: E/AndroidRuntime(25527): at android.widget.AbsListView$1.run(AbsListView.java:3468) 
11-04 20:54:45.673: E/AndroidRuntime(25527): at android.os.Handler.handleCallback(Handler.java:605) 
11-04 20:54:45.673: E/AndroidRuntime(25527): at android.os.Handler.dispatchMessage(Handler.java:92) 
11-04 20:54:45.673: E/AndroidRuntime(25527): at android.os.Looper.loop(Looper.java:137) 
11-04 20:54:45.673: E/AndroidRuntime(25527): at android.app.ActivityThread.main(ActivityThread.java:4512) 
11-04 20:54:45.673: E/AndroidRuntime(25527): at java.lang.reflect.Method.invokeNative(Native Method) 
11-04 20:54:45.673: E/AndroidRuntime(25527): at java.lang.reflect.Method.invoke(Method.java:511) 
11-04 20:54:45.673: E/AndroidRuntime(25527): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:982) 
11-04 20:54:45.673: E/AndroidRuntime(25527): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:749) 
11-04 20:54:45.673: E/AndroidRuntime(25527): at dalvik.system.NativeStart.main(Native Method)

任何导游？提前致谢。

来源

2014-11-04 I Was So Lost

你写的AsyncTask类，和你不使用它。您的堆栈跟踪显示您在主应用程序线程上从selectItem()调用ViewEventsOnMap()，并且您没有在任何地方使用MyAsyncTask。

来源

2014-11-04 13:09:15 CommonsWare

的viewEventsOnMap（）应该在后台做的，我已经当上创建名为异步任务类的。所以，当我的地图加载时，它立即显示所有标记，而无需从导航抽屉中选择。 – 2014-11-04 13:13:49

@IWasSoLost：“viewEventsOnMap（）应该在后台执行” - 不是根据您编写的代码。 “我在创建时调用了异步任务类” - 这并不重要，因为您不会从selectItem（）调用它，这是您的'NetworkOnMainThreadException'的来源。 – CommonsWare 2014-11-04 13:41:16

你有什么想法，这样我可以扭转我的代码，以我所期望的方式工作吗？ – 2014-11-04 13:45:35

您没有使用AsyncTask为您的网络电话。您已写入AsyncTask，但未完全使用它。

在导航抽屉中的项目的选择与您直接调用运行在UI线程的方法ViewEventsOnMap()。

而不是做你应该打电话给你AsycnTask

来源

2014-11-04 13:11:17 Rohit5k2

viewEventsOnMap（）应该在后台执行，我在创建时调用了异步任务类。所以，当我的地图加载时，它立即显示所有标记，而无需从导航抽屉中选择。 – 2014-11-04 13:12:44

方法ViewEventsOnMap（）正在进行网络调用，它必须在AsyncTask中没有任何选择。找到解决方法。 – Rohit5k2 2014-11-04 13:14:57

但你有什么想法吗？ – 2014-11-04 13:16:01

的Android异步任务NetworkOnMainThreadException

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