NsdManager.DiscoveryListener.onServiceFound的NsdServiceInfo中的Host为null

Question

我正在尝试将NsdServiceInfo的mHost作为参数传递给NsdManager.DiscoveryListener.onServiceFound(),但它为null.我有两个Android设备,其中设备1是服务器,设备2是客户端.

这是我在设备1中注册服务器的方式

public void registerService(int port, InetAddress myIp) {
    NsdServiceInfo serviceInfo  = new NsdServiceInfo();
    serviceInfo.setPort(port);
    serviceInfo.setServiceName(this.serviceName);
    serviceInfo.setServiceType(SERVICE_TYPE);
    serviceInfo.setHost(myIp);

    this.nsdManager.registerService(
            serviceInfo, NsdManager.PROTOCOL_DNS_SD, registrationListener);
}

这就是我初始化DiscoveryListener的方法

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

        @Override
        public void onServiceFound(NsdServiceInfo service) {
            Log.d(TAG, "Service discovery success" + service);
            if (!service.getServiceType().equals(SERVICE_TYPE)) {
                Log.d(TAG, "Unknown Service Type: " + service.getServiceType());
            } else if (service.getHost() == myIp) {
                Log.d(TAG, "Same machine: " + service.getHost());
            } else if (service.getServiceName().contains(serviceName)){
                nsdManager.resolveService(service, resolveListener);
            }
        }
   ...
   }
}

但是service.getHost()返回null.
有什么建议吗？

Answer 1

我刚刚遇到了同样的问题,并在Google网页发现页面的帮助下设法解决了这个问题.

http://developer.android.com/training/connect-devices-wirelessly/nsd.html

问题是在发现服务时不知道连接信息.您必须先解决它,然后才能使用getHost().

你已经有了这条线:

    nsdManager.resolveService(service, resolveListener);

resolveListener变量包含成功和失败的回调.您希望在成功确定连接信息后使用getHost().以下是Google的解决方案监听器:

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

        @Override
        public void onResolveFailed(NsdServiceInfo serviceInfo, int errorCode) {
            // Called when the resolve fails.  Use the error code to debug.
            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;
            }
            service = serviceInfo;
            int port = service.getPort();
            InetAddress host = service.getHost(); // getHost() will work now
        }
    };
}