解析xml文件时出错Android

Question

我已经通过xml解析为我的应用程序添加了版本检查。

但是，当我试着执行它时，它在我已经贴在那儿的异常运行：

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 

您可以通过使用获得Eclipse项目的GitHub： https://github.com/LookedPath/lookedpath_android_applications/tree/FirstApp/PrimaLezione

应该是什么我做？

Answer 1

您正在收到NetworkOnMainThreadException。这意味着您尝试以某种方式访问​​网络（例如，下载图像）在您的主（UI）线程中。为了更好地响应API 11中的用户界面，此功能被禁用。您需要为您的网络使用不同的线程，最简单的方法是使用AsyncTask。如果您需要保持连接一段时间（例如实时通信），您也可以创建一个新的类，该类延伸Thread或HandlerThread，并自行管理与UI线程之间的通信（使用Handler）。不要忘记UI不是线程安全的。

Answer 2

最好的方法是使用AsyncTask。

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

异步任务让u到与UI交互当u fiish下载线程（或可运行）不 让您与UI交互。

如果您需要在UI中进行更改，您需要创建一个处理程序并在该处理程序中运行更改，但AsyncTask会为您实现它。