解析xml文件時出錯Android

Question

我已經通過xml解析爲我的應用程序添加了版本檢查。

但是，當我試着執行它時，它在我已經貼在那兒的異常運行：

11-03 19:21:36.809: E/AndroidRuntime(16531): FATAL EXCEPTION: main 
11-03 19:21:36.809: E/AndroidRuntime(16531): java.lang.RuntimeException: Unable to instantiate activity ComponentInfo{com.lookedpath.firstlesson/com.lookedpath.firstlesson.Update}: android.os.NetworkOnMainThreadException 
11-03 19:21:36.809: E/AndroidRuntime(16531): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2099) 
11-03 19:21:36.809: E/AndroidRuntime(16531): at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2210) 
11-03 19:21:36.809: E/AndroidRuntime(16531): at android.app.ActivityThread.access$600(ActivityThread.java:142) 
11-03 19:21:36.809: E/AndroidRuntime(16531): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1208) 
11-03 19:21:36.809: E/AndroidRuntime(16531): at android.os.Handler.dispatchMessage(Handler.java:99) 
11-03 19:21:36.809: E/AndroidRuntime(16531): at android.os.Looper.loop(Looper.java:137) 
11-03 19:21:36.809: E/AndroidRuntime(16531): at android.app.ActivityThread.main(ActivityThread.java:4931) 
11-03 19:21:36.809: E/AndroidRuntime(16531): at java.lang.reflect.Method.invokeNative(Native Method) 
11-03 19:21:36.809: E/AndroidRuntime(16531): at java.lang.reflect.Method.invoke(Method.java:511) 
11-03 19:21:36.809: E/AndroidRuntime(16531): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:791) 
11-03 19:21:36.809: E/AndroidRuntime(16531): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:558) 
11-03 19:21:36.809: E/AndroidRuntime(16531): at dalvik.system.NativeStart.main(Native Method) 
11-03 19:21:36.809: E/AndroidRuntime(16531): Caused by: android.os.NetworkOnMainThreadException 
11-03 19:21:36.809: E/AndroidRuntime(16531): at android.os.StrictMode$AndroidBlockGuardPolicy.onNetwork(StrictMode.java:1117) 
11-03 19:21:36.809: E/AndroidRuntime(16531): at java.net.InetAddress.lookupHostByName(InetAddress.java:385) 
11-03 19:21:36.809: E/AndroidRuntime(16531): at java.net.InetAddress.getAllByNameImpl(InetAddress.java:236) 
11-03 19:21:36.809: E/AndroidRuntime(16531): at java.net.InetAddress.getAllByName(InetAddress.java:214) 
11-03 19:21:36.809: E/AndroidRuntime(16531): at org.apache.http.impl.conn.DefaultClientConnectionOperator.openConnection(DefaultClientConnectionOperator.java:137) 
11-03 19:21:36.809: E/AndroidRuntime(16531): at org.apache.http.impl.conn.AbstractPoolEntry.open(AbstractPoolEntry.java:164) 
11-03 19:21:36.809: E/AndroidRuntime(16531): at org.apache.http.impl.conn.AbstractPooledConnAdapter.open(AbstractPooledConnAdapter.java:119) 
11-03 19:21:36.809: E/AndroidRuntime(16531): at org.apache.http.impl.client.DefaultRequestDirector.execute(DefaultRequestDirector.java:360) 
11-03 19:21:36.809: E/AndroidRuntime(16531): at org.apache.http.impl.client.AbstractHttpClient.execute(AbstractHttpClient.java:555) 
11-03 19:21:36.809: E/AndroidRuntime(16531): at org.apache.http.impl.client.AbstractHttpClient.execute(AbstractHttpClient.java:487) 
11-03 19:21:36.809: E/AndroidRuntime(16531): at org.apache.http.impl.client.AbstractHttpClient.execute(AbstractHttpClient.java:465) 
11-03 19:21:36.809: E/AndroidRuntime(16531): at com.lookedpath.firstlesson.XMLParser.getXmlFromUrl(XMLParser.java:35) 
11-03 19:21:36.809: E/AndroidRuntime(16531): at com.lookedpath.firstlesson.Update.<init>(Update.java:24) 
11-03 19:21:36.809: E/AndroidRuntime(16531): at java.lang.Class.newInstanceImpl(Native Method) 
11-03 19:21:36.809: E/AndroidRuntime(16531): at java.lang.Class.newInstance(Class.java:1319) 
11-03 19:21:36.809: E/AndroidRuntime(16531): at android.app.Instrumentation.newActivity(Instrumentation.java:1053) 
11-03 19:21:36.809: E/AndroidRuntime(16531): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2090) 
11-03 19:21:36.809: E/AndroidRuntime(16531): ... 11 more 

您可以通過使用獲得Eclipse項目的GitHub： https://github.com/LookedPath/lookedpath_android_applications/tree/FirstApp/PrimaLezione

應該是什麼我做？

Answer 1

您正在收到NetworkOnMainThreadException。這意味着您嘗試以某種方式訪問​​網絡（例如，下載圖像）在您的主（UI）線程中。爲了更好地響應API 11中的用戶界面，此功能被禁用。您需要爲您的網絡使用不同的線程，最簡單的方法是使用AsyncTask。如果您需要保持連接一段時間（例如實時通信），您也可以創建一個新的類，該類延伸Thread或HandlerThread，並自行管理與UI線程之間的通信（使用Handler）。不要忘記UI不是線程安全的。

Answer 2

最好的方法是使用AsyncTask。

http://developer.android.com/reference/android/os/AsyncTask.html

異步任務讓u到與UI交互當u fiish下載線程（或可運行）不 讓您與UI交互。

如果您需要在UI中進行更改，您需要創建一個處理程序並在該處理程序中運行更改，但AsyncTask會爲您實現它。