有人告诉我这是一个新问题。
我不知道如何做我正在做的事情，而我只是想快速地将一些东西放在一起。
但这就是我所拥有的：
public void newScanThing(String scanFormat, String scanContent){
URL u;
try {
u = new URL("http://www.searchupc.com/handlers/upcsearch.ashx?request_type=3&access_token=A98AC4EC-830D-4F6B-89D6-D6954361A8CA&upc=" + scanContent.toString());
BufferedReader br = new BufferedReader(new InputStreamReader(u.openStream()));
String stringBuff;
String scanData = "";
while ((stringBuff = br.readLine()) != null){
scanData += stringBuff;
}
br.close();
formatTxt.setText("FORMAT: " + scanFormat + " DATA: I don't crash.");
} catch (MalformedURLException mue) {
// crash
} catch (IOException ioe) {
// crash
}I know which line causes it to crash, and it is the scanData = new ... line. But I have no idea why. If you were to visit the link I visit, you would see the only thing in that URL is a single string. It's not even any HTML or anything, it's just a string.
这是我的函数调用：
newScanThing("UPC_A","816983011311");
无论如何，我做错了什么？我以前从未使用过这个。我需要在大约12个小时内得到这个字符串以获得概念证明，并且在我得到字符串之后我还有很多工作要做。那么提示？正确答案的手势？
也许只是一个快速而肮脏的解释我做错了什么，怎么做对，为什么这样做？
logcat的：
01-25 05:53:42.367: D/libEGL(13564): loaded /vendor/lib/egl/libEGL_POWERVR_SGX540_120.so
01-25 05:53:42.382: D/libEGL(13564): loaded /vendor/lib/egl/libGLESv1_CM_POWERVR_SGX540_120.so
01-25 05:53:42.390: D/libEGL(13564): loaded /vendor/lib/egl/libGLESv2_POWERVR_SGX540_120.so
01-25 05:53:42.492: D/OpenGLRenderer(13564): Enabling debug mode 0
01-25 05:53:42.500: E/SensorManager(13564): thread start
01-25 05:53:42.507: D/SensorManager(13564): registerListener :: handle = 1 name= BMA254 Acceleration Sensor delay= 200000 Listener= android.view.OrientationEventListener$SensorEventListenerImpl@41816ab8
01-25 05:53:42.593: W/IInputConnectionWrapper(13564): showStatusIcon on inactive InputConnection
01-25 05:53:54.406: D/AndroidRuntime(13564): Shutting down VM
01-25 05:53:54.406: W/dalvikvm(13564): threadid=1: thread exiting with uncaught exception (group=0x4106a2a0)
01-25 05:53:54.421: E/AndroidRuntime(13564): FATAL EXCEPTION: main
01-25 05:53:54.421: E/AndroidRuntime(13564): android.os.NetworkOnMainThreadException
01-25 05:53:54.421: E/AndroidRuntime(13564): at android.os.StrictMode$AndroidBlockGuardPolicy.onNetwork(StrictMode.java:1118)
01-25 05:53:54.421: E/AndroidRuntime(13564): at java.net.InetAddress.lookupHostByName(InetAddress.java:385)
01-25 05:53:54.421: E/AndroidRuntime(13564): at java.net.InetAddress.getAllByNameImpl(InetAddress.java:236)
01-25 05:53:54.421: E/AndroidRuntime(13564): at java.net.InetAddress.getAllByName(InetAddress.java:214)
01-25 05:53:54.421: E/AndroidRuntime(13564): at libcore.net.http.HttpConnection.<init>(HttpConnection.java:70)
01-25 05:53:54.421: E/AndroidRuntime(13564): at libcore.net.http.HttpConnection.<init>(HttpConnection.java:50)
01-25 05:53:54.421: E/AndroidRuntime(13564): at libcore.net.http.HttpConnection$Address.connect(HttpConnection.java:340)
01-25 05:53:54.421: E/AndroidRuntime(13564): at libcore.net.http.HttpConnectionPool.get(HttpConnectionPool.java:87)
01-25 05:53:54.421: E/AndroidRuntime(13564): at libcore.net.http.HttpConnection.connect(HttpConnection.java:128)
01-25 05:53:54.421: E/AndroidRuntime(13564): at libcore.net.http.HttpEngine.openSocketConnection(HttpEngine.java:315)
01-25 05:53:54.421: E/AndroidRuntime(13564): at libcore.net.http.HttpEngine.connect(HttpEngine.java:310)
01-25 05:53:54.421: E/AndroidRuntime(13564): at libcore.net.http.HttpEngine.sendSocketRequest(HttpEngine.java:289)
01-25 05:53:54.421: E/AndroidRuntime(13564): at libcore.net.http.HttpEngine.sendRequest(HttpEngine.java:239)
01-25 05:53:54.421: E/AndroidRuntime(13564): at libcore.net.http.HttpURLConnectionImpl.getResponse(HttpURLConnectionImpl.java:273)
01-25 05:53:54.421: E/AndroidRuntime(13564): at libcore.net.http.HttpURLConnectionImpl.getInputStream(HttpURLConnectionImpl.java:168)
01-25 05:53:54.421: E/AndroidRuntime(13564): at java.net.URL.openStream(URL.java:462)
01-25 05:53:54.421: E/AndroidRuntime(13564): at com.example.food2forkbarcode.MainActivity.newScanThing(MainActivity.java:60)
01-25 05:53:54.421: E/AndroidRuntime(13564): at com.example.food2forkbarcode.MainActivity.onClick(MainActivity.java:28)
01-25 05:53:54.421: E/AndroidRuntime(13564): at android.view.View.performClick(View.java:4222)
01-25 05:53:54.421: E/AndroidRuntime(13564): at android.view.View$PerformClick.run(View.java:17273)
01-25 05:53:54.421: E/AndroidRuntime(13564): at android.os.Handler.handleCallback(Handler.java:615)
01-25 05:53:54.421: E/AndroidRuntime(13564): at android.os.Handler.dispatchMessage(Handler.java:92)
01-25 05:53:54.421: E/AndroidRuntime(13564): at android.os.Looper.loop(Looper.java:137)
01-25 05:53:54.421: E/AndroidRuntime(13564): at android.app.ActivityThread.main(ActivityThread.java:4895)
01-25 05:53:54.421: E/AndroidRuntime(13564): at java.lang.reflect.Method.invokeNative(Native Method)
01-25 05:53:54.421: E/AndroidRuntime(13564): at java.lang.reflect.Method.invoke(Method.java:511)
01-25 05:53:54.421: E/AndroidRuntime(13564): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:994)
01-25 05:53:54.421: E/AndroidRuntime(13564): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:761)
01-25 05:53:54.421: E/AndroidRuntime(13564): at dalvik.system.NativeStart.main(Native Method)
01-25 05:54:02.820: I/Process(13564): Sending signal. PID: 13564 SIG: 9
01-25 05:54:10.656: D/libEGL(13768): loaded /vendor/lib/egl/libEGL_POWERVR_SGX540_120.so
01-25 05:54:10.664: D/libEGL(13768): loaded /vendor/lib/egl/libGLESv1_CM_POWERVR_SGX540_120.so
01-25 05:54:10.671: D/libEGL(13768): loaded /vendor/lib/egl/libGLESv2_POWERVR_SGX540_120.so
01-25 05:54:10.781: D/OpenGLRenderer(13768): Enabling debug mode 0
01-25 05:54:10.789: E/SensorManager(13768): thread start
01-25 05:54:10.789: D/SensorManager(13768): registerListener :: handle = 1 name= BMA254 Acceleration Sensor delay= 200000 Listener= android.view.OrientationEventListener$SensorEventListenerImpl@41813160
01-25 05:54:12.187: D/AndroidRuntime(13768): Shutting down VM
01-25 05:54:12.187: W/dalvikvm(13768): threadid=1: thread exiting with uncaught exception (group=0x4106a2a0)
01-25 05:54:12.203: E/AndroidRuntime(13768): FATAL EXCEPTION: main
01-25 05:54:12.203: E/AndroidRuntime(13768): android.os.NetworkOnMainThreadException
01-25 05:54:12.203: E/AndroidRuntime(13768): at android.os.StrictMode$AndroidBlockGuardPolicy.onNetwork(StrictMode.java:1118)
01-25 05:54:12.203: E/AndroidRuntime(13768): at java.net.InetAddress.lookupHostByName(InetAddress.java:385)
01-25 05:54:12.203: E/AndroidRuntime(13768): at java.net.InetAddress.getAllByNameImpl(InetAddress.java:236)
01-25 05:54:12.203: E/AndroidRuntime(13768): at java.net.InetAddress.getAllByName(InetAddress.java:214)
01-25 05:54:12.203: E/AndroidRuntime(13768): at libcore.net.http.HttpConnection.<init>(HttpConnection.java:70)
01-25 05:54:12.203: E/AndroidRuntime(13768): at libcore.net.http.HttpConnection.<init>(HttpConnection.java:50)
01-25 05:54:12.203: E/AndroidRuntime(13768): at libcore.net.http.HttpConnection$Address.connect(HttpConnection.java:340)
01-25 05:54:12.203: E/AndroidRuntime(13768): at libcore.net.http.HttpConnectionPool.get(HttpConnectionPool.java:87)
01-25 05:54:12.203: E/AndroidRuntime(13768): at libcore.net.http.HttpConnection.connect(HttpConnection.java:128)
01-25 05:54:12.203: E/AndroidRuntime(13768): at libcore.net.http.HttpEngine.openSocketConnection(HttpEngine.java:315)
01-25 05:54:12.203: E/AndroidRuntime(13768): at libcore.net.http.HttpEngine.connect(HttpEngine.java:310)
01-25 05:54:12.203: E/AndroidRuntime(13768): at libcore.net.http.HttpEngine.sendSocketRequest(HttpEngine.java:289)
01-25 05:54:12.203: E/AndroidRuntime(13768): at libcore.net.http.HttpEngine.sendRequest(HttpEngine.java:239)
01-25 05:54:12.203: E/AndroidRuntime(13768): at libcore.net.http.HttpURLConnectionImpl.getResponse(HttpURLConnectionImpl.java:273)
01-25 05:54:12.203: E/AndroidRuntime(13768): at libcore.net.http.HttpURLConnectionImpl.getInputStream(HttpURLConnectionImpl.java:168)
01-25 05:54:12.203: E/AndroidRuntime(13768): at java.net.URL.openStream(URL.java:462)
01-25 05:54:12.203: E/AndroidRuntime(13768): at com.example.food2forkbarcode.MainActivity.newScanThing(MainActivity.java:60)
01-25 05:54:12.203: E/AndroidRuntime(13768): at com.example.food2forkbarcode.MainActivity.onClick(MainActivity.java:28)
01-25 05:54:12.203: E/AndroidRuntime(13768): at android.view.View.performClick(View.java:4222)
01-25 05:54:12.203: E/AndroidRuntime(13768): at android.view.View$PerformClick.run(View.java:17273)
01-25 05:54:12.203: E/AndroidRuntime(13768): at android.os.Handler.handleCallback(Handler.java:615)
01-25 05:54:12.203: E/AndroidRuntime(13768): at android.os.Handler.dispatchMessage(Handler.java:92)
01-25 05:54:12.203: E/AndroidRuntime(13768): at android.os.Looper.loop(Looper.java:137)
01-25 05:54:12.203: E/AndroidRuntime(13768): at android.app.ActivityThread.main(ActivityThread.java:4895)
01-25 05:54:12.203: E/AndroidRuntime(13768): at java.lang.reflect.Method.invokeNative(Native Method)
01-25 05:54:12.203: E/AndroidRuntime(13768): at java.lang.reflect.Method.invoke(Method.java:511)
01-25 05:54:12.203: E/AndroidRuntime(13768): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:994)
01-25 05:54:12.203: E/AndroidRuntime(13768): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:761)
01-25 05:54:12.203: E/AndroidRuntime(13768): at dalvik.system.NativeStart.main(Native Method)
01-25 05:55:03.835: D/dalvikvm(13768): GC_CONCURRENT freed 245K, 9% free 7464K/8199K, paused 6ms+3ms, total 44ms
01-25 05:57:28.851: D/dalvikvm(13768): GC_CONCURRENT freed 332K, 11% free 7572K/8455K, paused 16ms+2ms, total 63ms
答案 0 :(得分：1)
您得到的错误（NetworkOnMainThreadException）表示您正在尝试对主线程进行网络操作，而该主线程已不再授权。
一种解决方案是在AsyncTask中执行所有与网络相关的操作。你在Henry提供的链接上有一个很好的例子：How to fix android.os.NetworkOnMainThreadException?
基本上，您将创建一个继承AsyncTask的类，在此类的doInBackground方法中，您将执行网络操作，并且在同一类的onPostExecute中，您将执行后处理。您将通过创建新实例并调用.execute()来调用此类。