Question

我有部分代码从GPS获取数据，并应将其保存回API。

try{ 

        String Lat = URLEncoder.encode(Double.toString(loc.getLatitude()), "UTF-8");
        String Lng = URLEncoder.encode(Double.toString(loc.getLongitude()), "UTF-8");

        String currentLocationText = "My current location is: " + "Lat = " + Lat + "Lng = " + Lng;

        Log.d(LOG_TAG, currentLocationText);

        String urlString = "http://api/?lat="+Lat+"&lng="+Lng;

          URL url = new URL(urlString);
          URLConnection conn = url.openConnection();
          InputStream is = conn.getInputStream();

          StringWriter writer = new StringWriter();
          IOUtils.copy(is, writer, "UTF-8");
          String theString = writer.toString();

          Log.d(LOG_TAG, "Server response: ."+ theString);
      } catch (Exception e) {
          Log.d(LOG_TAG, "Exception: "+ e.getMessage());
      }

但是在运行时我在Logs中收到：

"Exception: null"

在我的清单文件中，我把：

 <uses-permission android:name="android.permission.INTERNET" />

抱歉，如果它看起来很乱（异常处理程序），我是PHP开发人员，这是我的第一步：）。

我怎么知道这是什么问题？我可以改进Exception消息以了解发生了什么吗？

编辑：得到了堆栈跟踪

01-16 21:47:14.759: D/MyLocationListener(2041): Exception: null
01-16 21:47:14.784: D/MyLocationListener(2041): Stack trace: android.os.NetworkOnMainThreadException
01-16 21:47:14.784: D/MyLocationListener(2041):     at android.os.StrictMode$AndroidBlockGuardPolicy.onNetwork(StrictMode.java:1144)
01-16 21:47:14.784: D/MyLocationListener(2041):     at java.net.InetAddress.lookupHostByName(InetAddress.java:385)
01-16 21:47:14.784: D/MyLocationListener(2041):     at java.net.InetAddress.getAllByNameImpl(InetAddress.java:236)
01-16 21:47:14.784: D/MyLocationListener(2041):     at java.net.InetAddress.getAllByName(InetAddress.java:214)
01-16 21:47:14.784: D/MyLocationListener(2041):     at libcore.net.http.HttpConnection.<init>(HttpConnection.java:70)
01-16 21:47:14.784: D/MyLocationListener(2041):     at libcore.net.http.HttpConnection.<init>(HttpConnection.java:50)
01-16 21:47:14.784: D/MyLocationListener(2041):     at libcore.net.http.HttpConnection$Address.connect(HttpConnection.java:340)
01-16 21:47:14.784: D/MyLocationListener(2041):     at libcore.net.http.HttpConnectionPool.get(HttpConnectionPool.java:87)
01-16 21:47:14.784: D/MyLocationListener(2041):     at libcore.net.http.HttpConnection.connect(HttpConnection.java:128)
01-16 21:47:14.784: D/MyLocationListener(2041):     at libcore.net.http.HttpEngine.openSocketConnection(HttpEngine.java:316)
01-16 21:47:14.784: D/MyLocationListener(2041):     at libcore.net.http.HttpEngine.connect(HttpEngine.java:311)
01-16 21:47:14.784: D/MyLocationListener(2041):     at libcore.net.http.HttpEngine.sendSocketRequest(HttpEngine.java:290)
01-16 21:47:14.784: D/MyLocationListener(2041):     at libcore.net.http.HttpEngine.sendRequest(HttpEngine.java:240)
01-16 21:47:14.784: D/MyLocationListener(2041):     at libcore.net.http.HttpURLConnectionImpl.getResponse(HttpURLConnectionImpl.java:282)
01-16 21:47:14.784: D/MyLocationListener(2041):     at libcore.net.http.HttpURLConnectionImpl.getInputStream(HttpURLConnectionImpl.java:177)
01-16 21:47:14.784: D/MyLocationListener(2041):     at com.example.gps_tracker.MyLocationListener.onLocationChanged(MyLocationListener.java:44)
01-16 21:47:14.784: D/MyLocationListener(2041):     at android.location.LocationManager$ListenerTransport._handleMessage(LocationManager.java:255)
01-16 21:47:14.784: D/MyLocationListener(2041):     at android.location.LocationManager$ListenerTransport.access$000(LocationManager.java:184)
01-16 21:47:14.784: D/MyLocationListener(2041):     at android.location.LocationManager$ListenerTransport$1.handleMessage(LocationManager.java:200)
01-16 21:47:14.784: D/MyLocationListener(2041):     at android.os.Handler.dispatchMessage(Handler.java:99)
01-16 21:47:14.784: D/MyLocationListener(2041):     at android.os.Looper.loop(Looper.java:176)
01-16 21:47:14.784: D/MyLocationListener(2041):     at android.app.ActivityThread.main(ActivityThread.java:5419)
01-16 21:47:14.784: D/MyLocationListener(2041):     at java.lang.reflect.Method.invokeNative(Native Method)
01-16 21:47:14.784: D/MyLocationListener(2041):     at java.lang.reflect.Method.invoke(Method.java:525)
01-16 21:47:14.784: D/MyLocationListener(2041):     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1046)
01-16 21:47:14.784: D/MyLocationListener(2041):     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:862)
01-16 21:47:14.784: D/MyLocationListener(2041):     at dalvik.system.NativeStart.main(Native Method)

我想我需要阅读并完全理解： How to fix android.os.NetworkOnMainThreadException?

Answer 1

在网络上使用AsyncTask获取和发布请求

Answer 2

您应该使用异步任务执行所有网络任务。目前，您的方法是阻止不允许的ui线程。这就是您收到错误的原因。

查看有关如何使用AsyncTask的信息：http://developer.android.com/reference/android/os/AsyncTask.html

Android JAVA HTTP GET请求 - 带有NULL消息的NetworkOnMainThreadException

2 个答案: