android - 从 JSON url 读取数据但 android 不允许它。NetworkOnMainThread 异常和 StrictMode$AndroidBlockGuardPolicy 错误

Question

我正在尝试在 Android 应用程序中使用 Google map 。 MainActivity 包含EditText、ImageButton 和MapView。当用户提供一些查询并点击 ImageButton 时，MainAcitivity 应该从 url 获取一些 JSON 数据，然后我需要使用该 JSON 数据在用户单击这些标记时创建标记和对话框。每当我运行该应用程序时，它都运行良好。但是当我单击 ImageButton 时，应用程序停止提供 logcat 错误 NetworkOnMainThreadException 和 StrickMode$AndroidBlockGuardPolicy。我附上了 logcat 输出和 MainActivity。我已经运行这个 JSON 程序来创建其他测试项目，它工作得很好。但是当我将它添加到 MainAcitivity 时，它不起作用。我相信，android 的安全策略阻止它从 url 获取数据。

那么这个错误的原因是什么，我怎样才能让这个Activity工作呢？非常感谢 friend 们的关注。如果您需要 CustomOverlayItem 对象或 JSON 对象的更多代码，请告诉我。

public class MainActivity extends MapActivity {

        private List<Home> listHome = new ArrayList<Home>();

        @Override
        public void onCreate(Bundle savedInstanceState) {

            super.onCreate(savedInstanceState);
            setContentView(R.layout.activity_main);

            MapView mv_map = (MapView) findViewById(R.id.mv_map);
            MapController mapController = mv_map.getController();
            mv_map.setBuiltInZoomControls(true);
            mapController.setZoom(5);
            Markers markers = new Markers(this.getResources().getDrawable(
                    R.drawable.ic_action_home), this);
            CustomOverlayItem items = new CustomOverlayItem(getuserLocation(),
                    "Checking", "Checking");
            List<Overlay> overlays = mv_map.getOverlays();
            markers.addOverlayItem(items);
            overlays.add(markers);

            ImageButton ib_search = (ImageButton) findViewById(R.id.ib_search);
            ib_search.setOnClickListener(new OnClickListener() {

            @Override
                public void onClick(View v) {
                    Json json = new Json();
                    listHome = json.getListHome();
                    EditText editText = (EditText) findViewById(R.id.et1_search);
                    editText.setText(listHome.get(0).getTitle().toString());
                }
            });

        }

        @Override
        public boolean onCreateOptionsMenu(Menu menu) {
            getMenuInflater().inflate(R.menu.activity_main, menu);
            return true;
        }

        @Override
        protected boolean isRouteDisplayed() {
            return false;
        }

        private GeoPoint getuserLocation() {
                GeoPoint geoPoint = new GeoPoint(19240000, -99120000);
            return geoPoint;
        }
    }

Logcat 输出:错误

08-04 16:26:55.253: E/Trace(1307): error opening trace file: No such file or directory (2)
08-04 16:26:57.743: E/MapActivity(1307): Couldn't get connection factory client
08-04 16:27:01.643: E/AndroidRuntime(1307): FATAL EXCEPTION: main
08-04 16:27:01.643: E/AndroidRuntime(1307): android.os.NetworkOnMainThreadException
08-04 16:27:01.643: E/AndroidRuntime(1307):     at android.os.StrictMode$AndroidBlockGuardPolicy.onNetwork(StrictMode.java:1117)
08-04 16:27:01.643: E/AndroidRuntime(1307):     at java.net.InetAddress.lookupHostByName(InetAddress.java:385)
08-04 16:27:01.643: E/AndroidRuntime(1307):     at java.net.InetAddress.getAllByNameImpl(InetAddress.java:236)
08-04 16:27:01.643: E/AndroidRuntime(1307):     at java.net.InetAddress.getAllByName(InetAddress.java:214)
08-04 16:27:01.643: E/AndroidRuntime(1307):     at libcore.net.http.HttpConnection.<init>(HttpConnection.java:70)
08-04 16:27:01.643: E/AndroidRuntime(1307):     at libcore.net.http.HttpConnection.<init>(HttpConnection.java:50)
08-04 16:27:01.643: E/AndroidRuntime(1307):     at libcore.net.http.HttpConnection$Address.connect(HttpConnection.java:341)
08-04 16:27:01.643: E/AndroidRuntime(1307):     at libcore.net.http.HttpConnectionPool.get(HttpConnectionPool.java:87)
08-04 16:27:01.643: E/AndroidRuntime(1307):     at libcore.net.http.HttpConnection.connect(HttpConnection.java:128)
08-04 16:27:01.643: E/AndroidRuntime(1307):     at libcore.net.http.HttpEngine.openSocketConnection(HttpEngine.java:315)
08-04 16:27:01.643: E/AndroidRuntime(1307):     at libcore.net.http.HttpEngine.connect(HttpEngine.java:310)
08-04 16:27:01.643: E/AndroidRuntime(1307):     at libcore.net.http.HttpEngine.sendSocketRequest(HttpEngine.java:289)
08-04 16:27:01.643: E/AndroidRuntime(1307):     at libcore.net.http.HttpEngine.sendRequest(HttpEngine.java:239)
08-04 16:27:01.643: E/AndroidRuntime(1307):     at libcore.net.http.HttpURLConnectionImpl.getResponse(HttpURLConnectionImpl.java:273)
08-04 16:27:01.643: E/AndroidRuntime(1307):     at libcore.net.http.HttpURLConnectionImpl.getInputStream(HttpURLConnectionImpl.java:168)
08-04 16:27:01.643: E/AndroidRuntime(1307):     at java.net.URL.openStream(URL.java:462)
08-04 16:27:01.643: E/AndroidRuntime(1307):     at com.incubers.map.json.Json.getListHome(Json.java:33)
08-04 16:27:01.643: E/AndroidRuntime(1307):     at com.incubers.map.MainActivity$1.onClick(MainActivity.java:53)
08-04 16:27:01.643: E/AndroidRuntime(1307):     at android.view.View.performClick(View.java:4084)
08-04 16:27:01.643: E/AndroidRuntime(1307):     at android.view.View$PerformClick.run(View.java:16966)
08-04 16:27:01.643: E/AndroidRuntime(1307):     at android.os.Handler.handleCallback(Handler.java:615)
08-04 16:27:01.643: E/AndroidRuntime(1307):     at android.os.Handler.dispatchMessage(Handler.java:92)
08-04 16:27:01.643: E/AndroidRuntime(1307):     at android.os.Looper.loop(Looper.java:137)
08-04 16:27:01.643: E/AndroidRuntime(1307):     at android.app.ActivityThread.main(ActivityThread.java:4745)
08-04 16:27:01.643: E/AndroidRuntime(1307):     at java.lang.reflect.Method.invokeNative(Native Method)
08-04 16:27:01.643: E/AndroidRuntime(1307):     at java.lang.reflect.Method.invoke(Method.java:511)
08-04 16:27:01.643: E/AndroidRuntime(1307):     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:786)
08-04 16:27:01.643: E/AndroidRuntime(1307):     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:553)
08-04 16:27:01.643: E/AndroidRuntime(1307):     at dalvik.system.NativeStart.main(Native Method)

Answer 1

NetworkOnMainThreadException当应用程序试图在其主线程上执行网络操作时抛出异常。使用 AsyncTask , Handler , HandlerThread用于从服务器获取 Json