问NdsManager安卓错误

EN

java.lang.IllegalArgumentException: listener already in useat android.net.nsd.NsdManager.registerService(NsdManager.java:485)
          at br.com.shootinghouse.sc.ServerActivity.registerService(ServerActivity.java:76)
          at br.com.shootinghouse.sc.ServerActivity.onResume(ServerActivity.java:50)
          at android.app.Instrumentation.callActivityOnResume(Instrumentation.java:1269)
          at android.app.Activity.performResume(Activity.java:6783)
          at android.app.ActivityThread.performResumeActivity(ActivityThread.java:3406)
          at android.app.ActivityThread.handleResumeActivity(ActivityThread.java:3469)
          at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2732)
          at android.app.ActivityThread.-wrap12(ActivityThread.java)
          at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1477)
          at android.os.Handler.dispatchMessage(Handler.java:102)
          at android.os.Looper.loop(Looper.java:154)
          at android.app.ActivityThread.main(ActivityThread.java:6119)
          at java.lang.reflect.Method.invoke(Native Method)
          at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:886)
          at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:776)

public class ServerActivity extends MonitorarSerChamadoActivity {
private Manager manager;
private LiteListener listener;
private String SERVICE_NAME = "Server device";
private String SERVICE_TYPE = "_http._tcp.";
private int SERVICE_Port = 5432;
private NsdManager mNsdManager;
@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    mNsdManager = (NsdManager) getSystemService(getApplicationContext().NSD_SERVICE);
    registerService(SERVICE_Port);
    try {
        manager = new Manager(new AndroidContext(getApplicationContext()), Manager.DEFAULT_OPTIONS);
    } catch (Throwable e) {
        e.printStackTrace();
    }
    startListener();
    URL url = null;
    try {
        url = new URL("http://" + getLocalIpAddress() + ":" + SERVICE_Port + "/banco144");
    } catch (Throwable e) {
        e.printStackTrace();
    }
    System.out.println("Listening on :: " + url.toString() + " "
            + SERVICE_NAME + " " +
            SERVICE_TYPE);
}
@Override
protected void onResume() {
    super.onResume();
    if (mNsdManager != null) {
        registerService(SERVICE_Port);
    }

}
void startListener() {
    listener = new LiteListener(manager, SERVICE_Port, null);
    Thread thread = new Thread(listener);
    thread.start();
}
@Override
protected void onDestroy() {
    if (mNsdManager != null) {
        mNsdManager.unregisterService(mRegistrationListener);
    }
    super.onDestroy();
}
public void registerService(int port) {
    NsdServiceInfo serviceInfo = new NsdServiceInfo();
    serviceInfo.setServiceName(SERVICE_NAME);
    serviceInfo.setServiceType(SERVICE_TYPE);
    serviceInfo.setPort(port);
    try {
        mNsdManager.registerService(serviceInfo, NsdManager.PROTOCOL_DNS_SD, mRegistrationListener);
    } catch (Exception e) {
        e.printStackTrace();
    }
}
NsdManager.RegistrationListener mRegistrationListener = new NsdManager.RegistrationListener() {
    @Override
    public void onServiceRegistered(NsdServiceInfo NsdServiceInfo) {
        SERVICE_NAME = NsdServiceInfo.getServiceName();
    }
    @Override
    public void onRegistrationFailed(NsdServiceInfo serviceInfo, int errorCode) {
    }
    @Override
    public void onServiceUnregistered(NsdServiceInfo serviceInfo) {
    }
    @Override
    public void onUnregistrationFailed(NsdServiceInfo serviceInfo, int errorCode) {
    }
};
public String getLocalIpAddress() {
    WifiManager wm = (WifiManager) getApplicationContext().getSystemService(WIFI_SERVICE);
    return Formatter.formatIpAddress(wm.getConnectionInfo().getIpAddress());
}