Question

我正在尝试通过网络中的网络服务发现API（NSD）连接两个Android设备。在实施过程中，我遵循了Android官方网页。其中一台设备充当服务器，另一台设备充当客户端。我要求网络提供下一个空闲端口。但是，一旦我通过registerService（nsdsInfo，NsdManager.PROTOCOL_DNS_SD，mRegistrationListener）在网络中注册服务器，则nsdsInfo中的参数为空。因此，在调用此代码行之前，nsdsInfo对象包含正确的端口和正确的主机等。调用此方法之后，侦听器onServiceRegistered（）中的Callback方法包含Port = 0和Host = null。

是否有任何猜测为什么在注册过程中会丢失端口和主机名，但是注册仍然成功？另一方面，即使触发了注册回调“ onServiceRegistrered（）”，其他设备也无法发现服务器。

预先感谢大家！

//Const
    private static final String SERVICE_TYPE = "_speech._tcp";
    private static final String SERVICE_NAME = "speech";

    public WiFiServiceRegistry(Context ctx) throws IOException {

        this.context = ctx;

        initializeSocketAndPort();
        initializeNsdService();
        initializeRegistrationListener();

        if (nsdManager == null)
            nsdManager = (NsdManager) context.getSystemService(Context.NSD_SERVICE);
        System.out.println("nsdsinfo host" + nsdsInfo.getServiceName());
        System.out.println("nsdsinfo port" + nsdsInfo.getPort());
        nsdManager.registerService(nsdsInfo, NsdManager.PROTOCOL_DNS_SD, mRegistrationListener);
    }

    /**
     * Initializes the NsdServiceInfo.
     */
    private void initializeNsdService(){
        nsdsInfo = new NsdServiceInfo();
        nsdsInfo.setServiceName(SERVICE_NAME);
        nsdsInfo.setServiceType(SERVICE_TYPE);
        nsdsInfo.setPort(mLocalPort);
    }

    /**
     * Initializes the socket and port. Parameter 0 means that the next available port is used (dynamic).
     * @throws IOException
     */
    private void initializeSocketAndPort() throws IOException {
        mServerSocket = new ServerSocket(0);
        mLocalPort = mServerSocket.getLocalPort();
    }

    /**
     * Inizializes the registrationListener. Keeps track of the registration status.
     */
    private void initializeRegistrationListener(){
        mRegistrationListener = new NsdManager.RegistrationListener() {
            @Override
            public void onRegistrationFailed(NsdServiceInfo serviceInfo, int errorCode) {
                System.out.println("WiFiServiceRegistry: Registration failed");
            }

            @Override
            public void onUnregistrationFailed(NsdServiceInfo serviceInfo, int errorCode) {
                System.out.println("WiFiServiceRegistry: Unregistration failed");
            }

            @Override
            public void onServiceRegistered(NsdServiceInfo serviceInfo) {
                System.out.println("WiFiServiceRegistry: Registered service");
                System.out.println("WiFiServiceRegistry: Port " + serviceInfo.getPort());
                System.out.println("WiFiServiceRegistry: Host " + serviceInfo.getHost());
                System.out.println("WiFiServiceRegistry: ServiceName " + serviceInfo.getServiceName());
            }

            @Override
            public void onServiceUnregistered(NsdServiceInfo serviceInfo) {
                System.out.println("WiFiServiceRegistry: Unregistered service");
            }
        };
    }

Android NSD：registerService返回端口0和主机null

0 个答案: