Android NSD onServiceFound（）没有被调用

第一次尝试在Android中进行IP发现。我使用了http://developer.android.com/training/connect-devices-wirelessly/nsd.html#discover并编写了代码。我没有注册该设备，只是在网络中发现服务。当我在模拟器或设备上运行项目时，onDiscoveryStarted（）被调用，但onServiceFound（）永远不会被调用。请在下面找到我的代码。任何输入都非常感谢。谢谢！Android NSD onServiceFound（）没有被调用

public class MainActivity extends AppCompatActivity { 

    private Button discoverButton; 

    Context mContext; 

    NsdManager mNsdManager; 
    NsdManager.ResolveListener mResolveListener; 
    NsdManager.DiscoveryListener mDiscoveryListener; 
    NsdManager.RegistrationListener mRegistrationListener; 

    public static final String SERVICE_TYPE = "_http._tcp."; 
    public static final String TAG = "MyApp_MAIN_CLIENT"; 
    public String mServiceName = "MyApp"; 

    /* 
    * public static final String SERVICE_TYPE = "_http._tcp."; 
    public static final String TAG = "NsdHelper"; 
    public String mServiceName = "NsdChat"; 
    * */ 

    NsdServiceInfo mService; 
    private Handler mUpdateHandler; 

    @Override 
    protected void onCreate(Bundle savedInstanceState) { 
     super.onCreate(savedInstanceState); 
     setContentView(R.layout.activity_main); 

     mNsdManager = (NsdManager) this.getSystemService(Context.NSD_SERVICE); 
     discoverButton = (Button) findViewById(R.id.netButton); 
     discoverButton.setOnClickListener(new View.OnClickListener() { 
      public void onClick(android.view.View v) { 
       initializeDiscoveryListener(); 
       initializeResolveListener(); 
       discoverServices(); 

      } 
     }); 

    } 

    public void discoverServices() { 
     mNsdManager.discoverServices(
       SERVICE_TYPE, NsdManager.PROTOCOL_DNS_SD, mDiscoveryListener); 
    } 


    public void initializeDiscoveryListener() { 

     // Instantiate a new DiscoveryListener 
     mDiscoveryListener = new NsdManager.DiscoveryListener() { 

      // Called as soon as service discovery begins. 
      @Override 
      public void onDiscoveryStarted(String regType) { 
       Log.d(TAG, "Service discovery started"); 
      } 

      @Override 
      public void onServiceFound(NsdServiceInfo service) { 
       // A service was found! Do something with it. 
       Log.d(TAG, "Service discovery success" + service); 
       if (!service.getServiceType().equals(SERVICE_TYPE)) { 
        // Service type is the string containing the protocol and 
        // transport layer for this service. 
        Log.d(TAG, "Unknown Service Type: " + service.getServiceType()); 
       } /*else if (service.getServiceName().equals(mServiceName)) { 
        // The name of the service tells the user what they'd be 
        // connecting to. It could be "Bob's Chat App". 
        Log.d(TAG, "Same machine: " + mServiceName); 
       } 
       //else if (service.getServiceName().contains("NsdChat")){*/ 
       else{ 
        mNsdManager.resolveService(service, mResolveListener); 
       } 
      } 

      @Override 
      public void onServiceLost(NsdServiceInfo service) { 
       // When the network service is no longer available. 
       // Internal bookkeeping code goes here. 
       Log.e(TAG, "service lost" + service); 
      } 

      @Override 
      public void onDiscoveryStopped(String serviceType) { 
       Log.i(TAG, "Discovery stopped: " + serviceType); 
      } 

      @Override 
      public void onStartDiscoveryFailed(String serviceType, int errorCode) { 
       Log.e(TAG, "Discovery failed: Error code:" + errorCode); 
       mNsdManager.stopServiceDiscovery(this); 
      } 

      @Override 
      public void onStopDiscoveryFailed(String serviceType, int errorCode) { 
       Log.e(TAG, "Discovery failed: Error code:" + errorCode); 
       mNsdManager.stopServiceDiscovery(this); 
      } 
     }; 
    }// end of initializeListener() 


    public void initializeResolveListener() { 
     mResolveListener = new NsdManager.ResolveListener() { 

      @Override 
      public void onResolveFailed(NsdServiceInfo serviceInfo, int errorCode) { 
       Log.e(TAG, "Resolve failed" + errorCode); 
      } 

      @Override 
      public void onServiceResolved(NsdServiceInfo serviceInfo) { 
       Log.e(TAG, "Resolve Succeeded. " + serviceInfo); 

       if (serviceInfo.getServiceName().equals(mServiceName)) { 
        Log.d(TAG, "Same IP."); 
        return; 
       } 
       mService = serviceInfo; 
       int port = mService.getPort(); 
       InetAddress host = mService.getHost(); 
       Log.d(TAG,host.toString()); 
      } 
     }; 
    }//end of initializeResolveListener 


    @Override 
    protected void onPause() { 
     super.onPause(); 
     stopDiscovery(); 
     tearDown(); 

    } 

    @Override 
    protected void onResume() { 
     super.onResume(); 
     discoverServices(); 
    } 

    @Override 
    protected void onDestroy() { 
     tearDown(); 
     super.onDestroy(); 
    } 

    public void stopDiscovery() { 
     mNsdManager.stopServiceDiscovery(mDiscoveryListener); 
    } 


    public void tearDown() { 
     mNsdManager.unregisterService(mRegistrationListener); 
    } 
}

来源

2016-04-22 pws35

_“我不是注册设备，只要发现服务在网络中” _。这就是原因。您无法发现尚未注册的服务。一个设备应该注册其他设备将发现的服务......（关于'NSD'示例的建议：不要在同一设备上注册和发现服务） – Onik

Android NSD文档特别指出'注册'步骤是可选的。如果您不想注册设备，请转至步骤2：发现其他服务 – pws35

尝试从“_http._tcp。”中删除最后一个点。 - >“_http._tcp”; – Dmitry