Android的錯誤，而解析XML - android.os.NetworkOnMainThreadException

Question

我收到以下錯誤.....

08-18 00:02:19.230: D/CLIPBOARD(17993): Hide Clipboard dialog at Starting input: finished by someone else... ! 
08-18 00:02:21.515: E/Connectivity(17993): true 
08-18 00:02:21.535: D/AndroidRuntime(17993): Shutting down VM 
08-18 00:02:21.535: W/dalvikvm(17993): threadid=1: thread exiting with uncaught exception (group=0x40c3c1f8) 
08-18 00:02:21.545: E/AndroidRuntime(17993): FATAL EXCEPTION: main 
08-18 00:02:21.545: E/AndroidRuntime(17993): java.lang.RuntimeException: Unable to start activity ComponentInfo{org.yipl.rssfeed/org.yipl.rssfeed.News}: android.os.NetworkOnMainThreadException 
08-18 00:02:21.545: E/AndroidRuntime(17993): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1968) 
08-18 00:02:21.545: E/AndroidRuntime(17993): at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:1993) 
08-18 00:02:21.545: E/AndroidRuntime(17993): at android.app.ActivityThread.access$600(ActivityThread.java:127) 
08-18 00:02:21.545: E/AndroidRuntime(17993): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1159) 
08-18 00:02:21.545: E/AndroidRuntime(17993): at android.os.Handler.dispatchMessage(Handler.java:99) 
08-18 00:02:21.545: E/AndroidRuntime(17993): at android.os.Looper.loop(Looper.java:137) 
08-18 00:02:21.545: E/AndroidRuntime(17993): at android.app.ActivityThread.main(ActivityThread.java:4507) 
08-18 00:02:21.545: E/AndroidRuntime(17993): at java.lang.reflect.Method.invokeNative(Native Method) 
08-18 00:02:21.545: E/AndroidRuntime(17993): at java.lang.reflect.Method.invoke(Method.java:511) 
08-18 00:02:21.545: E/AndroidRuntime(17993): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:790) 
08-18 00:02:21.545: E/AndroidRuntime(17993): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:557) 
08-18 00:02:21.545: E/AndroidRuntime(17993): at dalvik.system.NativeStart.main(Native Method) 
08-18 00:02:21.545: E/AndroidRuntime(17993): Caused by: android.os.NetworkOnMainThreadException 
08-18 00:02:21.545: E/AndroidRuntime(17993): at android.os.StrictMode$AndroidBlockGuardPolicy.onNetwork(StrictMode.java:1099) 
08-18 00:02:21.545: E/AndroidRuntime(17993): at java.net.InetAddress.lookupHostByName(InetAddress.java:391) 
08-18 00:02:21.545: E/AndroidRuntime(17993): at java.net.InetAddress.getAllByNameImpl(InetAddress.java:242) 
08-18 00:02:21.545: E/AndroidRuntime(17993): at java.net.InetAddress.getAllByName(InetAddress.java:220) 
08-18 00:02:21.545: E/AndroidRuntime(17993): at org.apache.http.impl.conn.DefaultClientConnectionOperator.openConnection(DefaultClientConnectionOperator.java:137) 
08-18 00:02:21.545: E/AndroidRuntime(17993): at org.apache.http.impl.conn.AbstractPoolEntry.open(AbstractPoolEntry.java:164) 
08-18 00:02:21.545: E/AndroidRuntime(17993): at org.apache.http.impl.conn.AbstractPooledConnAdapter.open(AbstractPooledConnAdapter.java:119) 
08-18 00:02:21.545: E/AndroidRuntime(17993): at org.apache.http.impl.client.DefaultRequestDirector.execute(DefaultRequestDirector.java:360) 
08-18 00:02:21.545: E/AndroidRuntime(17993): at org.apache.http.impl.client.AbstractHttpClient.execute(AbstractHttpClient.java:555) 
08-18 00:02:21.545: E/AndroidRuntime(17993): at org.apache.http.impl.client.AbstractHttpClient.execute(AbstractHttpClient.java:487) 
08-18 00:02:21.545: E/AndroidRuntime(17993): at org.apache.http.impl.client.AbstractHttpClient.execute(AbstractHttpClient.java:465) 
08-18 00:02:21.545: E/AndroidRuntime(17993): at org.yipl.rssfeed.XMLParser.getXmlFromUrl(XMLParser.java:46) 
08-18 00:02:21.545: E/AndroidRuntime(17993): at org.yipl.rssfeed.News.onCreate(News.java:50) 
08-18 00:02:21.545: E/AndroidRuntime(17993): at android.app.Activity.performCreate(Activity.java:4465) 
08-18 00:02:21.545: E/AndroidRuntime(17993): at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1052) 
08-18 00:02:21.545: E/AndroidRuntime(17993): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1932) 
08-18 00:02:21.545: E/AndroidRuntime(17993): ... 11 more 

我試着用logcat的跟蹤誤差和下面的代碼中發現的錯誤：

public String getXmlFromUrl(String url) { 
    String xml = null; 

    try { 
     // defaultHttpClient 
     DefaultHttpClient httpClient = new DefaultHttpClient(); 
     HttpPost httpPost = new HttpPost(url); 

     HttpResponse httpResponse = httpClient.execute(httpPost);//I Found error here in this line... 

     HttpEntity httpEntity = httpResponse.getEntity(); 

     xml = EntityUtils.toString(httpEntity); 

    } catch (UnsupportedEncodingException e) { 
     e.printStackTrace(); 
    } catch (ClientProtocolException e) { 
     e.printStackTrace(); 
    } catch (IOException e) { 
     e.printStackTrace(); 
    } 
    // return XML 
    Log.e("ErrorPositionTestiong", xml); 
    return xml; 
} 

我的這個程序是XML解析函數的一部分..我不明白是什麼錯誤的意思.. 請幫助我..在此先感謝。

Answer 1

這是嚴格模式違規。簡而言之，您不應該在主線程上執行任何網絡或數據庫操作。使用AsyncTask獲取XML。