如何让对等WiFi服务发现工作？

Question

我正在尝试使用两个具有点对点WiFi连接的Android设备构建服务器 - 客户端架构.我在客户端和服务器之间有明确的区别,所以我试图删除不必要的代码.使用http://developer.android.com/training/connect-devices-wirelessly/nsd-wifi-direct.html上的说明我已经......

PeerToPeerService

public class PeerToPeerService {
    private static final Logger LOG = LoggerFactory.getLogger(PeerToPeerService.class);

    private WifiP2pManager mManager;
    private WifiP2pManager.Channel mChannel;
    private final Context mContext;
    private final WifiP2pDnsSdServiceInfo mService;

    public PeerToPeerService(Context context, String name) {
        mContext = context;

        Map<String, String> record = new HashMap<String, String>();
        record.put(Constants.SERVICE_PROPERTY_NAME, name);
        record.put(Constants.SERVICE_PROPERTY_PORT, "12345");

        mService = WifiP2pDnsSdServiceInfo.newInstance(
                "_test", "_presence._tcp", record);
    }

    public void start() {
        mManager = (WifiP2pManager) mContext.getSystemService(Context.WIFI_P2P_SERVICE);
        mChannel = mManager.initialize(mContext, mContext.getMainLooper(), null);

        mManager.addLocalService(mChannel, mService, new ActionListener() {
            @Override
            public void onSuccess() {
                LOG.info("Started Service");
            }

            @Override
            public void onFailure(int error) {
                LOG.warn("Failed to Start Service: {}", error);
            }
        });
    }

    public void stop() {
        mManager.removeLocalService(mChannel, mService, null);
        mManager = null;
        LOG.info("Stopped Service");
    }
}

PeerToPeerClient

public class PeerToPeerClient {
    private static final Logger LOG = LoggerFactory.getLogger(PeerToPeerClient.class);

    private WifiP2pManager mManager;
    private WifiP2pManager.Channel mChannel;
    private final Context mContext;

    public PeerToPeerClient(Context context) {
        mContext = context;
    }

    public void findServices() {
        mManager = (WifiP2pManager) mContext.getSystemService(Context.WIFI_P2P_SERVICE);
        mChannel = mManager.initialize(mContext, mContext.getMainLooper(), null);

        mManager.setDnsSdResponseListeners(mChannel,
                new DnsSdServiceResponseListener() {
                    @Override
                    public void onDnsSdServiceAvailable(String instanceName,
                            String registrationType, WifiP2pDevice device) {
                        LOG.info("A");
                        LOG.info("Service Found: {}:{}", instanceName, registrationType);
                    }
                }, 
                new DnsSdTxtRecordListener() {
                    @Override
                    public void onDnsSdTxtRecordAvailable(String fullDomainName, Map<String, String> record,
                            WifiP2pDevice device) {
                        LOG.info("B");
                        LOG.info("{}:{} is {}", device.deviceName, 
                                record.get(Constants.SERVICE_PROPERTY_PORT), record.get(Constants.SERVICE_PROPERTY_NAME));
                    }
                });

        WifiP2pDnsSdServiceRequest serviceRequest = WifiP2pDnsSdServiceRequest.newInstance();
        mManager.addServiceRequest(mChannel, serviceRequest,
                new ActionListener() {
                    @Override
                    public void onSuccess() {
                        LOG.info("Added service discovery request");
                    }

                    @Override
                    public void onFailure(int error) {
                        LOG.info("Failed adding service discovery request: {}", error);
                    }
                });

        mManager.discoverServices(mChannel, new ActionListener() {
            @Override
            public void onSuccess() {
                LOG.info("Service discovery initiated");
            }

            @Override
            public void onFailure(int arg0) {
                LOG.info("Service discovery failed");
            }
        });
    }
}

每个ActionListener都调用onSuccess,任何地方都没有失败.但我从来没有得到任何setDnsSdResponseListeners回调.我可能出错的任何想法？

Answer 1

我有一些在Android设备上使用Wi-Fi Direct的经验,我正在编写一个应用程序来连接设备ad-hoc并通过此链接进行聊天.

要在Wi-Fi Direct上发现,两个设备都需要扫描,即.mWifiP2pManager.discoverPeers().奇怪的是,这也影响了发现DnsTxtRecordServices.因此,我发现如果你scanning( discoverPeers())在两台设备上启动它然后启动它就有效discoverPeers().

希望这可以帮助!:)