Question

我正在构建一个Java服务器应用程序（在PC上运行），它使用id selector将自己注册到本地网络，以及一个应该使用JmDNS发现java服务器的Android客户端应用程序。登记/> 当我首先运行Android应用程序，然后运行java服务器时，应用程序成功发现注册的java服务器但是当我第一次运行服务器然后运行Android应用程序时，onServiceFound方法调用但public class Server { public static String mServiceName = "NsdApp"; public static final String SERVICE_TYPE = "_http._tcp.local"; static ServerSocket mServerSocket; public static void main(String[] args) throws IOException { System.out.println("START"); try { mServerSocket = new ServerSocket(0); } catch (IOException e) { System.out.println("ServerSocket(0) FAILED"); } int mPort = mServerSocket.getLocalPort(); JmDNS jmdns = JmDNS.create(); ServiceInfo info = ServiceInfo.create(SERVICE_TYPE, mServiceName, mPort, "B"); jmdns.registerService(info); System.out.println("REGISTERED"); jmdns.close(); Thread mReceiveMessage = new Thread(new ReceiveMessage()); mReceiveMessage.start(); System.out.println("END"); } public static class ReceiveMessage implements Runnable { public void run() { System.out.println("WAITING_FOR_MESSAGE"); try { Socket clientSocket = mServerSocket.accept(); InputStreamReader inputStreamReader = new InputStreamReader(clientSocket.getInputStream()); BufferedReader bufferedReader = new BufferedReader(inputStreamReader); String message = bufferedReader.readLine(); System.out.println(message); bufferedReader.close(); inputStreamReader.close(); clientSocket.close(); System.out.println("END_THREAD"); } catch (IOException ex) { System.out.println("Problem in message reading"); } } } }方法从未触发 - 安卓应用程序没有发现服务器。在我看来这是一种意想不到的行为。

成功案例：
Android应用日志：
08-24 22：42：06.157 NSD_DISCOVER onCreate
08-24 22：42：06.373 NSD_DISCOVER：onDiscoveryStarted服务发现开始了 08-24 22：42：30.256 NSD_DISCOVER：onServiceFound已知服务类型：_http._tcp。
08-24 22：42：30.293 NSD_DISCOVER：onServiceResolved Resolve Succeeded。名称：NsdApp，类型：._ http._tcp，主机：/10.0.0.2，端口：52288

Java服务器日志：
START
已注册
END
WAITING_FOR_MESSAGE
你好世界
END_THREAD

失败案例：

Android应用日志：
08-24 22：05：21.690 NSD_DISCOVER：onCreate
08-24 22：05：21.908 NSD_DISCOVER：onDiscoveryStarted服务发现开始

Java服务器日志：
START
已注册
END
WAITING_FOR_MESSAGE

服务器代码

public class MainActivity extends Activity {

public static final String TAG = "NSD_DISCOVER";
public static final String SERVICE_TYPE = "_http._tcp.";
NsdManager.DiscoveryListener mDiscoveryListener;
NsdManager.ResolveListener mResolveListener;
NsdManager mNsdManager;
int port;
InetAddress host;


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

    Log.v(TAG, "onCreate");

    mNsdManager = (NsdManager) getSystemService(Context.NSD_SERVICE);
    initializeResolveListener();
    initializeDiscoveryListener();
    mNsdManager.discoverServices(SERVICE_TYPE, NsdManager.PROTOCOL_DNS_SD, mDiscoveryListener);
}


public void initializeDiscoveryListener() {
    mDiscoveryListener = new NsdManager.DiscoveryListener() {

        @Override
        public void onDiscoveryStarted(String regType) {
            Log.v(TAG, "onDiscoveryStarted Service discovery started");
        }

        @Override
        public void onServiceFound(NsdServiceInfo service) {
            if (!service.getServiceType().equals(SERVICE_TYPE)) {
                Log.v(TAG, "onServiceFound Unknown Service Type: " + service.getServiceType());
            } else {
                Log.v(TAG, "onServiceFound Known Service Type: " + service.getServiceType());
                mNsdManager.resolveService(service, mResolveListener);
            }
        }

        @Override
        public void onServiceLost(NsdServiceInfo service) {
            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);
        }
    };
}


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

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

        @Override
        public void onServiceResolved(NsdServiceInfo serviceInfo) {
            Log.v(TAG, "onServiceResolved Resolve Succeeded. " + serviceInfo);
            port = serviceInfo.getPort();
            host = serviceInfo.getHost();

            SendMessage sendMessageTask = new SendMessage();
            sendMessageTask.execute();
        }
    };
}


private class SendMessage extends AsyncTask<Void, Void, Void> {

    @Override
    protected Void doInBackground(Void... params) {
        try {

            Socket client;
            PrintWriter printwriter;

            client = new Socket(host, port); 
            printwriter = new PrintWriter(client.getOutputStream(), true);
            printwriter.write("hello world"); 

            printwriter.flush();
            printwriter.close();
            client.close(); 

        } catch (UnknownHostException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        }
        return null;
    }
}

客户代码

//myProto object is deserialized using google protobuf API
ProtobufDatumWriter<MyProto> pbWriter = new ProtobufDatumWriter<MyProto>(MyProto.class);
FileOutputStream fo = new FileOutputStream(args[0]);
Encoder e = EncoderFactory.get().binaryEncoder(fo, null);
pbWriter.write(myProto, e);
fo.flush();

}

使用网络服务发现在Java服务器和Android客户端之间进行通信

0 个答案: