WiFi 局域网通信 - 发现服务和解析

1. nsdManager

nsdManager = requireContext().getSystemService(Context.NSD_SERVICE) as NsdManager

2.  NsdManager.DiscoveryListener

注意：在onStartDiscoveryFailed 和 onStopDiscoveryFailed里不要调用nsdManager.stopServiceDiscovery(this) 方法，会出现crash问题；如下方式调用：

if (discoveryListener != null) {Log.d(TAG, "start : loadData ")nsdManager.stopServiceDiscovery(discoveryListener)
}discoveryListener = object : NsdManager.DiscoveryListener {override fun onDiscoveryStarted(regType: String) {Log.d(TAG, "Service discovery started")}override fun onServiceFound(service: NsdServiceInfo) {Log.d(TAG, "Service discovery success: $service")Log.d(TAG, "Service discovery serviceName: ${service.serviceName}")when {service.serviceType != SERVICE_TYPE ->Log.d(TAG, "Unknown Service Type: ${service.serviceType}")service.serviceType == SERVICE_TYPE -> {Log.d(TAG, "start : resolveListener ")resolveService(service)}}}override fun onServiceLost(service: NsdServiceInfo) {// When the network service is no longer available.Log.e(TAG, "service lost: $service")}override fun onDiscoveryStopped(serviceType: String) {Log.i(TAG, "Discovery stopped: $serviceType")}override fun onStartDiscoveryFailed(serviceType: String, errorCode: Int) {Log.e(TAG, "onStart Discovery failed: Error code:$errorCode")}override fun onStopDiscoveryFailed(serviceType: String, errorCode: Int) {Log.e(TAG, "onStop Discovery failed: Error code:$errorCode")}
}

//SERVICE_TYPE 为你自定义的服务名称，比如 const val SERVICE_TYPE = "_test-rct._tcp."
nsdManager.discoverServices(SERVICE_TYPE, NsdManager.PROTOCOL_DNS_SD, discoveryListener)

3. NsdManager.ResolveListener

private fun resolveService(service: NsdServiceInfo) {val resolveListener = object : NsdManager.ResolveListener {override fun onResolveFailed(serviceInfo: NsdServiceInfo, errorCode: Int) {Log.e(TAG, "Resolve failed: $errorCode")}override fun onServiceResolved(serviceInfo: NsdServiceInfo) {val port: Int = serviceInfo.portval host =serviceInfo.host.hostAddressLog.d(TAG, "Resolve port: $port")Log.d(TAG, "Resolve host: $host")}}nsdManager.resolveService(service, resolveListener)
}