应用程序崩溃与Android 4.0.3 url.openStream（）在Android 4.0.3

Question

try{ 
     String stringURL = ""; ///some url 
     URL url = new URL(stringURL); 
     Reader reader = new InputStreamReader(url.openStream()); 
     user = new Gson().fromJson(reader, User.class); 
     } 
    catch (MalformedURLException e) 
     { 

     } 
     catch (IOException e) 
     { 

     } 

当我试图解析JSON响应在Android 4.0.3 url.openStream（）它崩溃。但是，在2.3.3上它是有效的。

堆栈跟踪

05-05 02:43:07.259: D/WebSettings(2172): mDataPath: /data/data/com.example.myvk 
05-05 02:43:07.560: W/dalvikvm(2172): threadid=1: thread exiting with uncaught exception (group=0x40c661f8) 
05-05 02:43:07.580: E/AndroidRuntime(2172): FATAL EXCEPTION: main 
05-05 02:43:07.580: E/AndroidRuntime(2172): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.myvk/com.example.myvk.WallActivity}: android.os.NetworkOnMainThreadException 
05-05 02:43:07.580: E/AndroidRuntime(2172):  at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1956) 
05-05 02:43:07.580: E/AndroidRuntime(2172):  at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:1981) 
05-05 02:43:07.580: E/AndroidRuntime(2172):  at android.app.ActivityThread.access$600(ActivityThread.java:123) 
05-05 02:43:07.580: E/AndroidRuntime(2172):  at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1147) 
05-05 02:43:07.580: E/AndroidRuntime(2172):  at android.os.Handler.dispatchMessage(Handler.java:99) 
05-05 02:43:07.580: E/AndroidRuntime(2172):  at android.os.Looper.loop(Looper.java:137) 
05-05 02:43:07.580: E/AndroidRuntime(2172):  at android.app.ActivityThread.main(ActivityThread.java:4424) 
05-05 02:43:07.580: E/AndroidRuntime(2172):  at java.lang.reflect.Method.invokeNative(Native Method) 
05-05 02:43:07.580: E/AndroidRuntime(2172):  at java.lang.reflect.Method.invoke(Method.java:511) 
05-05 02:43:07.580: E/AndroidRuntime(2172):  at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:787) 
05-05 02:43:07.580: E/AndroidRuntime(2172):  at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:554) 
05-05 02:43:07.580: E/AndroidRuntime(2172):  at dalvik.system.NativeStart.main(Native Method) 
05-05 02:43:07.580: E/AndroidRuntime(2172): Caused by: android.os.NetworkOnMainThreadException 
05-05 02:43:07.580: E/AndroidRuntime(2172):  at android.os.StrictMode$AndroidBlockGuardPolicy.onNetwork(StrictMode.java:1105) 
05-05 02:43:07.580: E/AndroidRuntime(2172):  at java.net.InetAddress.lookupHostByName(InetAddress.java:391) 
05-05 02:43:07.580: E/AndroidRuntime(2172):  at java.net.InetAddress.getAllByNameImpl(InetAddress.java:242) 
05-05 02:43:07.580: E/AndroidRuntime(2172):  at java.net.InetAddress.getAllByName(InetAddress.java:220) 
05-05 02:43:07.580: E/AndroidRuntime(2172):  at libcore.net.http.HttpConnection.<init>(HttpConnection.java:71) 
05-05 02:43:07.580: E/AndroidRuntime(2172):  at libcore.net.http.HttpConnection.<init>(HttpConnection.java:50) 
05-05 02:43:07.580: E/AndroidRuntime(2172):  at libcore.net.http.HttpConnection$Address.connect(HttpConnection.java:351) 
05-05 02:43:07.580: E/AndroidRuntime(2172):  at libcore.net.http.HttpConnectionPool.get(HttpConnectionPool.java:86) 
05-05 02:43:07.580: E/AndroidRuntime(2172):  at libcore.net.http.HttpConnection.connect(HttpConnection.java:128) 
05-05 02:43:07.580: E/AndroidRuntime(2172):  at libcore.net.http.HttpEngine.openSocketConnection(HttpEngine.java:308) 
05-05 02:43:07.580: E/AndroidRuntime(2172):  at libcore.net.http.HttpsURLConnectionImpl$HttpsEngine.makeSslConnection(HttpsURLConnectionImpl.java:460) 
05-05 02:43:07.580: E/AndroidRuntime(2172):  at libcore.net.http.HttpsURLConnectionImpl$HttpsEngine.connect(HttpsURLConnectionImpl.java:432) 
05-05 02:43:07.580: E/AndroidRuntime(2172):  at libcore.net.http.HttpEngine.sendSocketRequest(HttpEngine.java:282) 
05-05 02:43:07.580: E/AndroidRuntime(2172):  at libcore.net.http.HttpEngine.sendRequest(HttpEngine.java:232) 
05-05 02:43:07.580: E/AndroidRuntime(2172):  at libcore.net.http.HttpURLConnectionImpl.getResponse(HttpURLConnectionImpl.java:273) 
05-05 02:43:07.580: E/AndroidRuntime(2172):  at libcore.net.http.HttpURLConnectionImpl.getInputStream(HttpURLConnectionImpl.java:168) 
05-05 02:43:07.580: E/AndroidRuntime(2172):  at libcore.net.http.HttpsURLConnectionImpl.getInputStream(HttpsURLConnectionImpl.java:270) 
05-05 02:43:07.580: E/AndroidRuntime(2172):  at com.example.myvk.WallActivity.loadProfile(WallActivity.java:73) 
05-05 02:43:07.580: E/AndroidRuntime(2172):  at com.example.myvk.WallActivity.onCreate(WallActivity.java:33) 
05-05 02:43:07.580: E/AndroidRuntime(2172):  at android.app.Activity.performCreate(Activity.java:4465) 
05-05 02:43:07.580: E/AndroidRuntime(2172):  at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1049) 
05-05 02:43:07.580: E/AndroidRuntime(2172):  at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1920) 
05-05 02:43:07.580: E/AndroidRuntime(2172):  ... 11 more 

Answer 1

这可能是由于在蜂窝推出的NetworkOnMainThreadException例外。要解决这个问题，你应该在一个单独的线程中完成所有的网络工作（你可以使用AsyncTask来进行信号处理）。

欲了解更多信息，你可以阅读这篇博客：http://www.androiddesignpatterns.com/2012/06/app-force-close-honeycomb-ics.html