Question

我有一个服务运行，它在局域网中接收广播消息，我已经从片段启动了服务，我想在片段被销毁时停止服务，但是当我调用stopservice时它给NPE。我的服务调用片段是：

public class Receive extends Fragment  {


   TextView tv1,tv2;
   Intent intent;
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
    // Inflate the layout for this fragment

    View rootView =inflater.inflate(R.layout.receive, container, false);

    intent = new Intent(getActivity(), Server.class);

    tv1=(TextView)rootView.findViewById(R.id.textView1);
    tv2=(TextView)rootView.findViewById(R.id.textView2);
    //getActivity().startService(intent);
    return rootView;
}
private BroadcastReceiver broadcastReceiver = new BroadcastReceiver() {
    @Override
    public void onReceive(Context context, Intent intent) {
        updateUI(intent);       
    }};

    private void updateUI(Intent intent) {

        Toast.makeText(getActivity().getApplicationContext(), "Yea!!! Service called", Toast.LENGTH_SHORT).show();
String message = intent.getStringExtra("messages"); 
String senderip = intent.getStringExtra("sender");

   tv2.setText(message);

   tv1.setText(senderip);
   }
    @Override
    public void onResume() {
        super.onResume();
        getActivity().startService(intent);
        getActivity().registerReceiver(broadcastReceiver, new IntentFilter(
                Server.UDP_BROADCAST));

        Log.i("UDP", "reg started");
    }

    @Override
    public void onPause() {
        super.onPause();
        getActivity(). unregisterReceiver(broadcastReceiver);
        getActivity().stopService(intent);
        Log.i("UDP", "unreg started");
    }
    }

我的服务是：

public class Server extends Service {
static String UDP_BROADCAST = "soft.b.peopleassist";

//Boolean shouldListenForUDPBroadcast = false;
DatagramSocket socket;
//Intent intent;
private void listenAndWaitAndThrowIntent(InetAddress broadcastIP, Integer port) throws Exception {
    byte[] recvBuf = new byte[15000];
    if (socket == null || socket.isClosed()) {
        socket = new DatagramSocket(port, broadcastIP);
        socket.setBroadcast(true);
    }
    //socket.setSoTimeout(1000);
    DatagramPacket packet = new DatagramPacket(recvBuf, recvBuf.length);
    Log.e("UDP", "Waiting for UDP broadcast");
    socket.receive(packet);

    String senderIP = packet.getAddress().getHostAddress();
    String message = new String(packet.getData());

    Log.e("UDP", "Got UDB broadcast from " + senderIP + ", message: " + message);

    broadcastIntent(senderIP, message);
    socket.close();
}

private void broadcastIntent(String senderIP, String message) {
Intent  intent = new Intent(Server.UDP_BROADCAST);
    intent.putExtra("sender", senderIP);
    intent.putExtra("messages", message);
    sendBroadcast(intent);
}

Thread UDPBroadcastThread;

void startListenForUDPBroadcast() {
    UDPBroadcastThread = new Thread(new Runnable() {
        public void run() {
            try {
                InetAddress broadcastIP = InetAddress.getByName("192.168.1.255"); //172.16.238.42 //192.168.1.255
                Integer port = 11111;
                while (shouldRestartSocketListen) {
                    listenAndWaitAndThrowIntent(broadcastIP, port);
                }
                //if (!shouldListenForUDPBroadcast) throw new ThreadDeath();
            } catch (Exception e) {
                Log.i("UDP", "no longer listening for UDP broadcasts cause of error " + e.getMessage());
            }
        }
    });
    UDPBroadcastThread.start();
}

private Boolean shouldRestartSocketListen=true;

void stopListen() {
    shouldRestartSocketListen = false;
    socket.close();
}

@Override
public void onCreate() {

};

@Override
public void onDestroy() {
    stopListen();
    //stopService(intent);
    Log.i("UDP", "Service stoped");
}


@Override
public int onStartCommand(Intent intent, int flags, int startId) {
    shouldRestartSocketListen = true;
    startListenForUDPBroadcast();
    Log.i("UDP", "Service started");
    return START_STICKY;
}

@Override
public IBinder onBind(Intent intent) {
    return null;
}

}

我的logcat是：

  09-03 09:17:21.995: D/gralloc_goldfish(908): Emulator without GPU emulation detected.
09-03 09:17:28.763: I/UDP(908): reg started
 09-03 09:17:28.853: I/UDP(908): Service started
    09-03 09:17:28.993: I/UDP(908): no longer listening for UDP broadcasts cause of error bind failed: EADDRNOTAVAIL (Cannot assign requested address)
  09-03 09:17:30.653: I/UDP(908): unreg started
 09-03 09:17:30.893: D/AndroidRuntime(908): Shutting down VM
    09-03 09:17:30.893: W/dalvikvm(908): threadid=1: thread exiting with uncaught exception (group=0x409961f8)
   09-03 09:17:30.963: E/AndroidRuntime(908): FATAL EXCEPTION: main
 09-03 09:17:30.963: E/AndroidRuntime(908): java.lang.RuntimeException: Unable to stop service soft.b.peopleassist.Server@4137dbb8: java.lang.NullPointerException
  09-03 09:17:30.963: E/AndroidRuntime(908):    at android.app.ActivityThread.handleStopService(ActivityThread.java:2405)
     09-03 09:17:30.963: E/AndroidRuntime(908):     at android.app.ActivityThread.access$2000(ActivityThread.java:122)
 09-03 09:17:30.963: E/AndroidRuntime(908):     at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1212)
  09-03 09:17:30.963: E/AndroidRuntime(908):    at android.os.Handler.dispatchMessage(Handler.java:99)
  09-03 09:17:30.963: E/AndroidRuntime(908):    at android.os.Looper.loop(Looper.java:137)
   09-03 09:17:30.963: E/AndroidRuntime(908):   at android.app.ActivityThread.main(ActivityThread.java:4340)
 09-03 09:17:30.963: E/AndroidRuntime(908):     at java.lang.reflect.Method.invokeNative(Native Method)
  09-03 09:17:30.963: E/AndroidRuntime(908):    at java.lang.reflect.Method.invoke(Method.java:511)
  09-03 09:17:30.963: E/AndroidRuntime(908):    at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:784)
  09-03 09:17:30.963: E/AndroidRuntime(908):    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:551)
 09-03 09:17:30.963: E/AndroidRuntime(908):     at dalvik.system.NativeStart.main(Native Method)
    09-03 09:17:30.963: E/AndroidRuntime(908): Caused by: java.lang.NullPointerException
  09-03 09:17:30.963: E/AndroidRuntime(908):    at soft.b.peopleassist.Server.stopListen(Server.java:68)
    09-03 09:17:30.963: E/AndroidRuntime(908):  at soft.b.peopleassist.Server.onDestroy(Server.java:78)
    09-03 09:17:30.963: E/AndroidRuntime(908):  at android.app.ActivityThread.handleStopService(ActivityThread.java:2388)
    09-03 09:17:30.963: E/AndroidRuntime(908):  ... 10 more
     09-03 09:17:33.533: I/Process(908): Sending signal. PID: 908 SIG: 9

先谢谢。

Answer 1

在stopListen()方法中设置stop boolean，然后立即关闭套接字。有可能，你的另一个线程正在深入研究它。我建议你在他们创建的线程中关闭套接字。例如catchblock中的socket.close()并将其从stopListen()中删除。

ServiceStop时出现空指针异常

1 个答案: